This is a transcript of the Gastropod episode Ripe for Global Domination: The Story of the Avocado, first released on May 8, 2018. It is provided as a courtesy and may contain errors.

NICOLA TWILLEY: Alright, I’m in my kitchen Cynthia, and I feel as though it’s time for some lunch.

CYNTHIA GRABER: I am thinking the same thing, and I have a really lovely ripe avocado here on the counter.

TWILLEY: I do too! I do too!

GRABER: Perfect! You might even think we planned this.

GRABER: Oh come on, don’t tell me we’re out of bread, that would be really bad.

TWILLEY: There’s no avocado toast without the toast.

GRABER: Oh here we go. God. Okay, I’ve got bread. I’m just cutting it into thin slices. The bread is ready, I’m just kind of laying out the thin slices of avocado on the toast. Okay, little mashing on the bread here.

TWILLEY: Yeah so I am so freaking bougie that I am going to put a few little pink slivers of pickled radish on mine.

GRABER: You have pink pickled radish ready for yours?

TWILLEY: Cynthia, I’m living that healthy southern California lifestyle.

GRABER: Okay, I’m sprinkling some beautiful salt on top.

TWILLEY: Oh my God, this so pretty. The pink on the green? I feel like I could literally invite Gwyneth Paltrow round to lunch.

TWILLEY: Hi Gwyneth, are your ears burning? We’re talking about you.

GRABER: No, don’t worry, we are not going to spend this episode talking about Gwyneth Paltrow. We are, though, going to be talking about an incredibly delicious fruit—yes, avocado is a fruit—and how it became the symbol of an aspirational lifestyle.

TWILLEY: We are Gastropod, the podcast that looks at food through the lens of science and history. I am Nicola Twilley.

GRABER: And I’m Cynthia Graber. So, this avocado toast thing, how in the world did it become a thing?

TWILLEY: More importantly, how did a fruit that is named after male genitalia become the poster child of the North American Free Trade Agreement and the next big thing in China?

PRE-ROLL

MUSIC

MARY LU ARPAIA: It’s a New World fruit. It’s native to Mexico and Central America.

TWILLEY: That’s Mary Lu Arpaia. She’s head of the avocado breeding program at UC Riverside, near me in sunny Southern California.

GRABER: Nobody is sure exactly where the avocado first came from, but the oldest evidence we have that people were eating avocados comes from settlements from 10,000 years ago in Puebla, in Central Mexico.

TWILLEY: And again, no one is exactly sure where and when the avocado was domesticated—it might have happened more than once. But it was probably at least 7,000 years ago. The oldest known culture in the Americas, the Caral civilization of Peru—archaeologists have found evidence that they likely ate domesticated avocados, more than 3000 years ago.

GRABER: The Caral don’t seem to have been eating corn or other grains, and the same is true for another early culture called the Mokaya in what’s now Mexico and Guatemala. And so avocado may have played a really important role in their diets as a major staple.

TWILLEY: And we know the Maya valued avocados—the symbol they used for the 14th month of the year in their calendar was an avocado.

BROOK LARMER: When the Spanish conquistadors came to Latin America back in the 16th century, they encountered this fruit that they had never seen before that had this Aztec name ahuacatl, which means testicle actually, in the old ancient Nahuatl language.

GRABER: Brook Larmer is the “On Money” columnist for The New York Times Magazine and wrote a recent story on avocados. The Aztecs called these strange bumpy fruits testicles because they hung low, often in groups of two.

TWILLEY: And they look kind of testically in shape. I mean, I can see testicles in anything, but still.

LARMER: But the Spanish conquistadors took that name and made it into aguacate, from which our avocado has now derived in English.

TWILLEY: The conquistadors were big avocado fans, right away. The first written description of the avocado comes in 1519, from a Spanish guy called Martin Fernandez de Enciso. He described it as quote “an orange, and when it is ready for eating it turns yellowish; that which it contains is like butter and is of marvelous flavor, so good and pleasing to the palate that it is a marvelous thing.”

GRABER: Other conquistadors sang the praise of avocados as well. They likened them to figs. They said that avocados are healthy fruit for sick people, and when eaten with sugar, is like a preserve. They also said that avocados are like pears, but better.

TWILLEY: From the Spanish records we can get an idea of how indigenous Mesoamericans were using the avocado. They documented instances when it was used to pay nobility as a tribute, but they also wrote that it was for sale in the open air markets of Tenochtitlan. And apparently pigs used to gorge on the ripe fruit when it fell from the trees. Their meat was said to have a particularly excellent flavor.

GRABER: So it’s no surprise that the Spanish quickly adopted the avocado as a favorite fruit and eventually distributed it to other Spanish colonies, all around the world, where they started to grow it, too. But the avocado didn’t become a major commercial crop until recently.

ARPAIA: Even though it was grown as a door yard crop tree throughout Central America and valued for thousands of years, there was no intensive agriculture production of avocados actually until the industry in California and to some extent an industry in Florida started just about 100 years ago.

TWILLEY: What this means is that folks like Mary Lu, they’ve still got a lot to learn about the avocado’s evolution and its different varieties and its botany in general compared to more established crops like wheat. What we do know is that the avocado really old, in flowering plant terms.

ARPAIA: It’s a member of the laurel family. This is a very, very ancient part of the angiosperms.

GRABER: So ancient in fact that you have to imagine back millions of years ago, to a time when huge ground sloths the size of giraffes and mammoths stomped around avocado trees. These are the types of animals that could swallow a pit that big and then poop it out. These mega-sized animals went extinct about 13,000 years ago, but rodents picked up the avocado reproduction baton. They gnaw on avocado flesh and leave the seed to grow.

TWILLEY: Not the avocado’s target audience, but hey, it works.

GRABER: So for thousands of years, these ancient backyard angiosperms, they came in all sorts of varieties, and sizes.

TWILLEY: But not here in California.

ARPAIA: Over time we’ve gone to the point where now here in California we’re 95 percent Hass.

TWILLEY: Hass is the name of an avocado variety—really, the avocado variety that you see in stores today.

ARPAIA: Hass was a chance seedling that was actually found in La Habra Heights.

TWILLEY: La Habra Heights is a neighborhood in southeast LA, just a few miles down the road from me.

GRABER: And guess who’s behind this chance seedling?

TWILLEY: Oh my God, it is none other than our old friend, the globe trotting food explorer David Fairchild.

DAN STONE: Fairchild picks up what he sees as the greatest avocado in Chile.

GRABER: In case you don’t remember, our most recent episode was all about Dan Stone’s book called The Food Explorer. And this is Dan, describing another one of Fairchild’s adventures.

STONE: He’s visiting Chile in 1897, and he explores and he finds this great variety. It’s got a thick skin, it’s got creamy flesh. It’s not stringy at all. And he collects a thousand seeds and sends them back to Washington in hopes that at least a few will survive. A few do. And they are received in Washington, they are propagated. They are sent out to research stations in southern California toward the coast, around Fallbrook area and greater Los Angeles.

TWILLEY: There were already some avocados in California. They were brought here in the 1850s by settlers from Nicaragua. But Fairchild’s shipment of a whole bunch of new varieties got people excited about avocados again.

STONE: And people start experimenting with avocados. Farmers start growing them and scientists start breeding their seeds and seeing how they could improve them. Amateurs get into it too. In fact one of them is a postal worker, a letter carrier and in his spare time he just grows avocados in his backyard and one day one sprouts even better.

ARPAIA: It was the seed that was planted in the mid 1920s and the grower who actually was a postal worker kept trying to top-on the tree to the variety that was the dominant variety of the day. The graft kept failing. Then he finally gave up for different reasons. And then all of a sudden he realized he actually had something of value.

STONE: It’s straighter, its fruit comes faster, its skin is even thicker, its flesh is even creamier and greener. And so he decides to patent it and his name was Rudolf Hass.

TWILLEY: The mother Hass tree—it was actually still alive and growing in La Habra Heights. Apparently it got to an astonishing 65 feet tall. When I read this, I got so excited I was about to jump in the car and visit it, but then I read some more, and it died in 2002, from the dreaded root rot. There’s a plaque there now, instead, and the mother tree wood is still preserved at a nursery in Ventura.

GRABER: But even though the mother Hass tree has become so venerated that there’s a plaque for it, back when Hass avocados were new, this variety wasn’t an immediate hit.

ARPAIA: And if you read some of the older literature though, the thing that it had going against it was the fact that it turned black. There was a very nice article written in the mid 1940s where they’re complaining about well, you know the Hass is a great tree. It’s a great fruit. But my God, it’s black, not green! Because the dominant variety in the 40s up through the 70s was a Fuerte, which was a green variety. So it just shows how things have changed.

GRABER: So the black color freaked out consumers. But even though it took a few decades, both growers and eaters did eventually get used to it. Because this brand new Hass avocado had a lot going for it.

ARPAIA: Well I can go—I can wax on forever on that one.

TWILLEY: Let’s wax. First of all, in California, the Hass avocado ripens at a very convenient time.

GRABER: Farmers can harvest the Hass in March through June, after the Fuerte’s harvest is over. But it’s not just an addition to the Fuerte…

ARPAIA: The other thing is is that the fruit hung on the tree better.

TWILLEY: Mary Lu is not yet done listing the Hass’s virtues.

ARPAIA: The fruit is very easy to handle. It hides a lot of blemishes when it’s ripe because it turns black.

TWILLEY: And, and, and. The Hass is also the only avocado that Mexico and Peru are allowed to ship to the U.S., which makes it a pretty popular choice there too.

ARPAIA: Because they have insect pests in their countries. And research that was done in Mexico indicated that the Hass actually is a very poor host to fruit flies.

GRABER: There are all sorts of varieties grown in Mexico, but the Hass is the only one they can export. So this explains why small, black nubby Hass avocados have come to dominate the supermarket shelves today. But why have avocados themselves become so super popular?

TWILLEY: Well, they weren’t, at least not during the great Hass-Fuerte battles of the 30s through the 70s. They weren’t big in the U.S. or much of the rest of the world. In Central America and the northern part of South America, though, the avocado has always been a hit.

LUIS MARIO TAPIO VARGAS: Here in Mexico in a commercial way avocado was grown in small orchards. Main type of avocado fruit was a small fruit and thin-skinned, with large seed and scarce pulp or meat. Low commercial value but good flavor.

GRABER: Luis Mario Tapio Vargas studies water and soil management at the National Research institute for Forests and Agriculture. He’s based in Michoacan.

TWILLEY: Even with the introduction of the Hass, which had more flesh than seed and a sturdier skin—even then, the rest of the world took some convincing. Part of the problem with the avocado was its name.

LARMER: In the early 20th century in the United States, it was marketed as the alligator pear. Which might explain why it never caught on because it’s not a great name.

GRABER: Not a great name at all. The California Avocado Growers’ Exchange complained in the 1920s that associating the delicious fruit with an alligator was, quote, ruining the avocado business!

TWILLEY: Eventually the growers got their way and we now call alligator pears by a bastardized version of the Spanish bastardized version of the Nahuatl word which means testicle fruit.

GRABER: Because testicle fruit also was clearly not going to be a winner.

TWILLEY: Testicles and alligators aside, the avocado had bigger problems that just its name. In the rest of the world, the places where the avocado wasn’t from—people had no idea how to eat it. It was a fruit, but it wasn’t sweet, it was sort of slippery, it didn’t really cook well.

LARMER: I think when people first encounter the avocado, they’re getting them kind of off the truck and they’re just not edible. They’re hard. They don’t really know what to do with them.

GRABER: So on top of all the avocado’s challenges, consumers are buying them unripe. It is not looking good for the avocado. So how did we get to today? Lauren Oyler wrote an article about the rise of avocado toast—yes, we’ll get to that—and she looked back at how a few bold eaters in the U.S. were at least trying avocados in the early 1900s.

TWILLEY: She found a New Yorker article from 1937, called Avocado, comma, or the future of eating, by one S.J. Perelman.

LAUREN OYLER: And he goes to a restaurant in Los Angeles and has an avocado sandwich on whole wheat and a lime rickey at a pharmacy called Best drugstores. And so at that point you can see at least that there’s the concept of avocado on bread is emerging in our culinary consciousness in America. And then I also founded a 1962 New York Times article that says you could put avocado in a toasted sandwich and that would be an unusual way to serve it.

GRABER: Lauren’s point is that most people were not eating avocados. There weren’t as many Mexicans in the U.S. back then, and most non-Mexican Americans at the time weren’t eating as many tacos or chips and guacamole as they are today.

TWILLEY: Most Americans at the time would not necessarily have known what guacamole was.

GRABER: Plus, avocados were seasonal and only grew in certain areas of California and Florida, and so they were expensive.

TWILLEY: In fact, at nearly 5 bucks an avocado, they were apparently often stolen from grocery stores. And they were marketed as fancy foods: if you really wanted to impress your guests, you could serve an avocado with lobster as a elegant appetizer. That’s actually how I first encountered the avocado—my mum would serve it at dinner parties with the hole where the pit used to be filled with prawn cocktail.

GRABER: Plus you know, the 60s and 70s, this is also the beginning of the whole crazy ‘fat is bad’ time in American history, and avocados are pretty fatty, and they would have been seen as unhealthy. So the California Avocado Commission responded with a marketing campaign.

TWILLEY: They poured hundreds of thousands of dollars in to this. The first step: convince folks that avocados are actually healthy.

AVOCADO AD

TWILLEY: Yep, that sexy avocado fan is the actress Angie Dickinson, and she is lying alluringly on her side, dressed casually in gold high heels and a shiny white leotard, just, you know, scooping an avocado out of its skin with a teaspoon.

GRABER: As one does. In a white leotard.

TWILLEY: We’ve got the video on our website for all your avocado-eating wardrobe inspo needs.

GRABER: I can see how this commercial would send everyone running to the supermarket. But that wasn’t all the commission did. They funded studies showing that the fat in avocado helped increase nutrient absorption. They partnered with Harvard to promote the Mediterranean diet, full of so-called healthy fats. This was an all-out avocado blitz.

TWILLEY: But there was another problem. People were buying these fancy avocados while they were shiny and green and trying to eat them. Which was not nearly as fun and delicious as eating a ripe avocado.

GRABER: The commission even introduced a mascot called Mr. Ripe. As in, make sure your avocados are actually ripe! And to get some attention, they launched a contest looking for his perfect mate—Ms. Ripe, who would, quote, exemplify the California lifestyle of good health and healthy eating.

TWILLEY: But even with Mr. and Ms. Ripe AND Angie Dickinson encouraging folks to put their avocados in a paper bag or on the windowsill and let them ripen for a few days, the fact remained: it’s annoying to have to plan in advance to get a ripe avocado. Who shops four days ahead?

GRABER: And then, Brook Larmer told us that an avocado farmer named Gil Henry came up with a revolutionary idea.

LARMER: But the guy who I talked to in Southern California who helped come up with this this idea—he and his children went up to the local market in L.A. and watched people buy avocados and he realized that people would go up there and kind of feel around the avocado and if they didn’t find a ripe one or one that gave a little bit to the thumb push they would just walk away.

TWILLEY: In fact, the avocado commission installed a hidden camera in a California supermarket in the early 1980s, and the footage showed shopper after shopper squeezing the fruit and putting it back down. It was just lost sale after lost sale.

LARMER: And so he had this idea—we will do this.

GRABER: This was invent ripening rooms for avocados! Gil modeled his avocado ripening rooms after after banana ripening rooms. They’re basically refrigerated rooms where the avocados would hang out, and small amounts of ethylene would be pumped in. Ethylene is a plant hormone and it’s what causes the fruit to ripen.

ARPAIA: And so that’s very, very important commercially.

GRABER: This way, all the avocados ripen together, at more or less the same time, before they even land on the grocery store shelf.

LARMER: And so first in Ralph’s grocery stores in Los Angeles and then that expanded to Kroger which owned Ralph’s and that became something where that was also a factor in getting people to buy avocados.

TWILLEY: Today, all avocados go through this ripening room process. It’s revolutionized the avocado business—the chances that you can find a ripe ready to eat avocado at the store are approximately 100 percent better than they were in the early 1980s. And so shoppers now put those avocados in their basket after squeezing them.

GRABER: And a side effect of all of this is that it causes the Hass avocado to fully take over the market. Beforehand, when avocados were sold unripe, the green Fuerte ones looked nicer, they were shiny and green. But once they’re sold ripe, the Fuertes would show any bruises to the soft fruit, while the black Hass avocados hide any small blemishes.

TWILLEY: So, between this massive marketing effort, the invention of the ripening room, the name change, and the nutrition message, the avocado is poised to finally become a regular part of the American diet. But the thing that really pushed it over the edge? Much less glamorous than Ms. Ripe. It was a trade agreement.

GRABER: But before we get to how NAFTA led to the avocado’s world domination, we have some sponsors to tell you about.

MID ROLL

GRABER: In 1994, the avocado finally hit the big time—because of the North American Free Trade Agreement. Yep, NAFTA.

LARMER: But something else had to happen first. There was a ban on Mexican avocados that was imposed way back in 1914, ostensibly over fears of boll weevils getting into the agricultural crops in California. And it protected the California farmers from infestation. But it also kind of protected them from cheap competition. So there was this great fear in the United States that opening the doors to Mexican avocados in this particular industry would would destroy the California industry.

TWILLEY: So when it came to the talks about the avocado during the NAFTA negotiations…

LARMER: Well, they were hardly talks, they were more arguments. The fights that went into trying to lift its ban were extremely heated. I talked to one U.S. distributor who said that he went into this meeting in southern California to talk about lifting the ban and he was a distributor so he favored bringing in Mexican imports. He said that he was spat at and shouted at and basically kicked out of the meeting.

GRABER: A few years after NAFTA was signed, the ban on Mexican avocados was finally lifted. At first it was just for 19 states in the northeast.

LARMER: Far away from California so that the New Englanders could consume avocados in the wintertime. That gradual incremental lifting of that restriction was full fully enacted by about a decade later. And that’s what really led to the explosion.

TWILLEY: And explosion is the right word.

LARMER: You know, back in 1997, Americans only consumed avocados in the summertime when the California avocados were harvested. None of those were imported. You know, today Americans can eat avocados year round almost anywhere—if they can afford it.

TWILLEY: Post-NAFTA, avocado demand has grown exponentially. Twenty-five years ago, Americans were eating barely one pound of avocado per person per year. Now it’s more than seven.

GRABER: The other thing that’s boomed is ways to eat all that avocado.

TWILLEY: To go back again to when I was a kid in the 80s, encountering avocados in England, we had them on the half shell. Like Angie Dickinson. Though not, I hasten to add, in a white leotard. You scooped out the flesh with a teaspoon. When the pit hole wasn’t being filled with something fancy like prawn cocktail, we used to put vinaigrette in there. But that was the only way I knew to eat an avocado.

GRABER: And I don’t remember even seeing anything like that, at least not in my house or my friends’ houses. I do think my family went out to kind of Tex-Mex restaurants on occasion. I remember one down the street from my house in the 80s.

LARMER: In the United States we have this Mexican-American community that is growing along with the explosion of Tex-Mex food.

GRABER: And so people like me and my family started to eat more guacamole in their everyday lives. It also became one of the foods popular to snack on during the Super Bowl, so the avocado commission decided to do a big PR push to get folks to eat even MORE guacamole during the Super Bowl.

AVOCADO SUPER BOWL AD

GRABER: If it’s not obvious, they are trying to hypnotize us all into consuming even more guacamole. And it worked! Super Bowl weekend became one of the most important dates for avocado consumption in the U.S..

TWILLEY: According to the Mexican Avocado Association, a full twelve percent of America’s annual avocado consumption takes place during the Super Bowl!

LARMER: But 80 percent of those are imported and almost nine out of 10 of those imports are from Mexico—specifically from the state of Michoacan.

GRABER: So Americans are eating lots of avocados—that’s a win for the marketing campaign and, in theory, the growers. But these avocados are from Mexico! Sounds like exactly the nightmare that the California growers were worried about. So, did this mean that California avocado farmers were doomed? What happened to them?

LARMER: Well, remarkably this is a case of the rising tide lifting all boats. The year-round availability of avocados helped expand the visibility and attractiveness of avocados for everybody. So there was the growing market and the explosion among consumers only helped the Californians.

TWILLEY: Part of this is because Mexico’s production actually fills a gap around the California growers season. Under the NAFTA rules, California avocados get priority during their season, and Mexico, where avocados bloom four times a year, gets everything else.

GRABER: But even if California could extend its season dramatically, the state couldn’t possibly meet this new and still growing demand for avocados even if the farmers wanted to. There isn’t enough water and land.

LARMER: And so they really need this kind of extra input from Mexican avocados. And so the analysis is that there’s a real benefit to the United States economy—not just that California agricultural growers are spared but also it’s adding many, many jobs. I think there’s something like 19,000 jobs—new jobs for American workers. More than two billion dollars added to U.S. GDP simply by avocados.

TWILLEY: OK, so California farmers are happy, American avocado eaters are happy. But what about the place where all these avocados are coming from?

LARMER: In Mexico, most of the avocados are grown in a single state: the state of Michoacan, which is in south central Mexico, not far west of Mexico City, that goes down to the Pacific coast. And it’s not something that’s run by big agribusiness. It’s actually there are 20,000 individual orchards that are coordinated by a National Association.

GRABER: Michoacan is the only state that’s actually legally allowed to export avocados to the U.S. And the state has been completely transformed by avocados.

LARMER: It dominates the agriculture in that state.

TWILLEY: So what has the rise of the avocado meant for Michoacan?

LARMER: Well it’s interesting. Michoacan is a beautiful state. It has volcanoes and forests. I remember my first trip to Michoacan way back a few decades ago was to see the sanctuary where Monarch butterflies migrate in the winter from the United States. And you know, these are butterflies that have come three generations or four generations since the original migrants to the United States and they all come back to the same trees in a couple different preserves in Michoacan state and in the state of Mexico. That was my first trip and it’s just—it’s a gorgeous state.

GRABER: Those volcanoes and forests are part of why Michoacan is so great for avocados—it has really fertile soil and lots of rainfall.

LARMER: In California one of the real issues is water because avocado trees are extremely thirsty. Michoacan is blessed with, I think more than 70 percent of the orchards are naturally fed by springs, rivers, natural irrigation.

TWILLEY: So water usage is not a big issue, at least in Michoacan. The bigger environmental issue, at least for now, is what the avocado is doing to all those gorgeous forests.

LARMER: The Mexican environmental authorities estimate that about 50,000 acres a year are deforested in the state of Michoacan.

GRABER: It’s a big problem—and it’s not just because of avocado farms. But they are one of the causes. We asked Mario, the researcher who works on forest and water issues.

TAPIO VARGAS: The natural forests has been deforested for three main causes: illegal logging, forest fires, and avocado planting.

LARMER: And about 30 percent of that is due to avocado growing. The growers association will respond that well, most of these new orchards were previously used for other crops that have transferred their growing to avocados because they’re much more lucrative.

TWILLEY: So the avocado is not the only culprit here.

GRABER: And, in case you you were worried about the future of the Monarch butterflies, the forests that are being cut down for avocados aren’t the ones where the Monarchs go to spend the winter. Those are higher up in colder areas that aren’t as good for avocado farming.

TWILLEY: But still, as an avocado eater, I would love to enjoy my daily dose of creamy green goodness without contributing to deforestation. Mario told us that there had been some discussion about a law that would protect the forest and actually require avocado growers to return 10 percent of their cultivated land to wild forest.

TAPIO VARGAS: I am not optimistic of this situation.

GRABER: The growers fought back. And the government wasn’t interested in pushing this law, partly because it has bigger things to deal with, like drugs. And partly because, Mario thinks that corrupt government officials are making money from avocados.

TWILLEY: So what should a concerned avocado eater do? Mario says that in fact, we are the ones who can make a difference.

TAPIO VARGAS: The only way to protect is that, for example, that the United States said, I don’t buy you more avocados if you continue deforesting your lands.

GRABER: This strategy—that American demand can make a difference—it worked in the past. Mario said that avocado crops had been poorly handled, there were lots of pesticides left on and bacteria, but Americans wouldn’t put up with that. So Mexican farmers improved their farming methods to meet the demand. Mario thinks the same thing could happen with the forests—that if US consumers demand avocados that don’t contribute to deforestation, that could help save the forests.

LARMER: And but there’s also another problem in Michoacan, which is that this is the center of the Mexican drug war.

TWILLEY: Drug cartels in Mexico have made so much money from Americans looking to smoke pot and take meth that they have actually pretty much replaced the government in some places. They are super powerful along the west coast and in Michoacan too.

LARMER: So you can imagine when avocado profits in the last 20 years started to rise the cartels were quite interested. I mean in Michoacan avocados are known as oro verde, you know, green gold. And the cartels became kind of an insidious influence within the avocado industry. There were different groups, one called the Knights Templar who kind of had this medieval chivalric code and came in but extorted growers, kidnapped owners, usurped land. They created a kind of almost a war like situation for growers—it became very dangerous for the larger owners especially. Today those the Knights Templar have faded from the scene, La Familia Michoacana has faded from the scene, and now there’s a small splinter group called Los Viagras, which is apparently named for the leader who had heavily moussed hair that kind of stood on its end.

TWILLEY: On one level, if anyone is going to control the testicle fruit trade, it should be the Viagra gang. But seriously—cartel violence is a gigantic problem.

GRABER: You may even have noticed reports in the U.S. media in recent years about blood avocados. I mean, it’s not just that we don’t to eat something that’s contributing to deforestation—I definitely don’t want to eat something that’s supporting the cartels!

TWILLEY: But Brook tells us that in the past couple of years, things have looked up a little.

LARMER: In response to a lot of this cartel activity many of these smaller towns have have created self-defense militias, usually formed by the owners themselves. Many of the owners have teamed together to try to keep the peace and keep their avocados. There’s one place in particular called Tancitaro, which has become famous as the last place where it has this kind of self-defense militia. It’s like an 80-person force where they surround their town with checkpoints and the producers have to work with armed bodyguards. But they’ve now celebrated four years without a kidnapping which is considered a success. So the cartels are still an influence on it, although they haven’t really slowed down production, which is quite amazing.

TWILLEY: And again, like the deforestation issue, the cartel violence is not entirely the avocados’ fault.

LARMER: I mean, first of all, I think that the drug cartels were not created by avocados, they happened to attract the cartels because of their lucrative nature.

GRABER: And actually, Mario says that avocados have been really good for Michoacan in a lot of ways.

TAPIO VARGAS: The avocado in orchards have permitted that the people, the poor people of many communities that was in the poverty, now they are in economic best conditions.

TWILLEY: And those economic benefits means that more people can stay in their homes with their families.

LARMER: Michoacan is a huge sending community—or has been a sending area for migrants to United States. But avocados have kept more people closer to the land without necessarily needing to migrate.

GRABER: Great to know that we can enjoy Mexican avocados with very little guilt. Because frankly, what would happen to Instagram feeds of <illennials if you took away their avocado toast? Just kidding, don’t write us angry emails.

TWILLEY: And for even less guilt—if you want to get rid of that lingering worry that your avocados from Mexico are contributing to deforestation—right now the best you can do is look for an organic, Rainforest Alliance, or Equal Exchange label. Rainforest Alliance and Equal Exchange avocados are hard to find, and organic doesn’t specifically guarantee that the grower is not cutting down virgin forest, but it does mean that the cultivation is less intensive and doesn’t pollute the groundwater as much. Not a perfect solution, but one that means you can go ahead and have your avocado and eat it on toast … just don’t expect to be able buy a house as well.

GRABER: As some would have you think. We are coming right back to take our usual nuanced look at the strange phenomenon that is avocado toast.

MID ROLL

OYLER: So I was actually talking to someone yesterday and I was like, oh I’m going to do an interview for a podcast about avocado toast and they were like yeah! what — it’s like — what is it exactly? I’m not really sure I understand? I’m like: it’s literally what it sounds like.

GRABER: It’s avocado. On toast.

TWILLEY: This is Lauren Oyler again, journalist and author of an in-depth look at the origins of avocado toast. And, in case you’ve been living in a cave for the past few years, avocado toast is having something of a moment right now.

OYLER: I feel like I came to avocado appreciation relatively late in life. I grew up in West Virginia and it’s not that we didn’t have avocados there but it’s not like one of the main food groups as it is in somewhere like New York or L.A. or even Berlin where I used to live.

GRABER: Lauren first noticed avocado being served on toast just a few years ago, when she moved to Berlin after college

OYLER: I don’t really remember eating it in college. And I graduated in 2012. And then when I lived in Berlin there are a lot of Australians living there and there are a lot of Australian cafes and I think that is probably the first time that I really noticed it on a menu.

TWILLEY: This is kind of late in avocado toast terms. Or at least in terms of the current wave of avocado toast. Because the question of avocado toast’s origins is a tricky one.

OYLER: Because you could certainly argue that avocado on a tortilla is the original avocado toast. right? But I think that’s a fundamentally different eating experience though it may be a predecessor to avocado toast—probably certainly is a predecessor to avocado toast.

GRABER: Which today is basically mashed avocado on toast, with maybe salt and pepper, and a few beautiful garnishes, like Nicky’s pickled pink radishes. That avocado toast is now found on the menu at restaurants and cafes basically everywhere. But Lauren wondered, where did it first come from, this current incarnation of avocado toast?

OYLER: There’s truth to the idea that Australia popularized avocado toast in the way that we know it today, which is sort of like a glamorous snack or meal that one can take a nice photo of for one’s Instagram account. Generally the first menu avocado toast is said to be at a cafe called Bill’s, I think, in 1993, in Sydney.

TWILLEY: Bill’s is a trendy all-day restaurant run by a well-known Australian chef called Bill Granger. He has confessed that he had no idea what he was starting when he first put avocado toast on his menu—he says he just thought avocado was a nice thing to have with a bit of tomato on toast.

OYLER: He published a recipe for avocado toast and he put in his cookbook and he was sort of like, I felt dumb putting a recipe for this in my cookbook because it’s so easy and obvious that you shouldn’t need a recipe. But I needed to fill a page.

GRABER: It wasn’t an overnight success. But then a little more than a decade later, an Australian chef named Chloe Osborne put avocado toast on the menu at Cafe Gitane in Manhattan.

TWILLEY: And then came Gwyneth. Paltrow, in case you’re not on first name terms. She put avocado toast in her 2013 cookbook, It’s All Good. And this, according to Lauren, is the moment when avocado toast went from being a thing you ate to a cultural phenomenon.

GRABER: So much so that Miley Cyrus has a tattoo of a half an avocado on her upper left arm. But when we say phenomenon—really, it’s kind of crazy how much the avocado and avocado toast, of course, have taken over.

AVOCADO AD

OYLER: So that. But then I also talked to some people who grew up in California in the 70s, and they were like, yeah we ate avocado on toast too.

TWILLEY: Yeah, not everyone is on board with the Bill’s-Cafe Gitane-Gwyneth origin story for avocado toast. Turns out people have been mashing avocado onto grain-based products for a while.

OYLER: After I published that article someone messaged me saying that her sister or something had spent a lot of time in Tel Aviv and that they always ate avocado on toast too, so that she thought that that meant that they had invented it.

GRABER: This was my experience—I first fell in love with avocado in the 90s, when I was living in Israel, and everyone just sliced avocado and put it on bread and sprinkled some salt on it. And I was like, this is delicious. Not revolutionary, just delicious.

OYLER: But I think trying to pinpoint the origin of it is a fool’s errand.

TWILLEY: No shit. But the real question is why? Why has avocado toast transcended its status as snack to become a symbol of everything?

GRABER: Part of it is that it’s become something that somehow seems pure and fresh and healthy and the good fatty, and somehow just perfect.

OYLER: I think as a status symbol. Avocado toast does does sort of advertise a certain lifestyle, which is like a wellness, a healthy lifestyle, which now is a kind of status symbol. And along with, like, doing yoga or going to Soul Cycle or going on a vacation to, like, Joshua Tree or something, avocado toast can, like, signify a certain kind of person and a certain kind of aspirational lifestyle.

TWILLEY: And it turns out that avocado toast is the perfect visual aid to advertise that lifestyle. It is the Instagram food par excellence. Last July, British Vogue reported that 3 million new pictures of avocado toast are uploaded to Instagram every day! Which truly says something about our times.

GRABER: I can’t even wrap my head around that figure. So why in the world has avocado toast taken over Instagram? What makes it such a perfect model? Once again, Lauren has the analysis.

OYLER: I think the color green of an avocado is bright and alluring but it’s not so bright that you can’t pair it with other colors. So you often see like a radish on avocado toast or like shaved—maybe like shaved beets or some kind of beet-like thing and so with the contrasting with the pink or the purple, it looks really, really nice.

TWILLEY: It’s beautiful and healthy and… it’s expensive.

OYLER: So there was a controversy semi recently in which I think an Australian investor or a millionaire or some sort of rich Australian non-Millennial was deriding the Millennial generation and saying that the reason we couldn’t afford to buy houses was because we’re spending so much money on avocado toast and coffees that cost four dollars.

TWILLEY: A tsunami of people helpfully told this dude he had his head up his ass and the real reason Millennials can’t buy homes is not actually because they’re spending all their money on avocado toast.

OYLER: But because of the raging income inequality and the subprime mortgage crisis and all the sort of economic stuff that has been pushed onto us from the older generations. And while I agree with the structural critique of his statement, I also do feel like avocado toast is quite expensive. And also it’s something that you can make at home for very cheap. And so I don’t want to say I see where he’s coming from because it was a stupid comment. But avocado toast is quite expensive. I mean, like, you can get it for like 13 dollars in some places in New York. Which is more than I’m going to spend on a piece of toast, shall we say.

GRABER: Look, I get it, sometimes you’re out at a cafe and they have awesome bread, and they put fun garnishes on it, and you want a piece of avocado toast. For Lauren, though, it’s come to mean something more.

OYLER: When I encounter avocado toast on a menu today, I always have this sort of like pain—this feeling of yearning because I at least still cannot justify ordering it in a restaurant though I see people doing it all the time. And I’m always like if only I were— like I feel like there’s—at some income level I will be frivolous enough to order an avocado toast in a restaurant. But still there’s like a barrier to me. It just seems so, like, luxurious.

TWILLEY: When you hear about Miley Cyrus having an avocado tattoo or avocado toast breaking Instagram and denying a whole generation home ownership, you think: we must be at peak avocado. But no.

GRABER: Because the future of avocados? It’s probably not in the US at all.

LARMER: In the year 2010, there were fewer than two tonnes of avocados imported into China. A small sedan could carry that many avocados. But since then it has become much more widespread mostly among young Millennials and the upper middle class but as a healthy fruit. And it’s known in China as the butter fruit, which seems to me like a perfect name for the avocado because that’s exactly what it feels like when you eat it—so buttery.

TWILLEY: So OK, in 2010, there was a car-load of butter fruit sold in the whole of China. That was the situation seven years ago.

LARMER: Last year, 32,000 tonnes were imported into China. And this is partly a marketing campaign and also partly kind of a young urban middle class kind of reaching for a global craze.

GRABER: Brook says Chinese entrepreneurs are building ripening rooms for avocados. They’re starting to talk about growing avocados in China. We’ve had our boom here in the U.S., and now that boom is moving on to other shores.

LARMER: Chinese have an unbelievable ability to adapt and incorporate new things into their cuisine. They are omnivores of the first order and also have a very, very widely diverse palate. And the avocado is a flavor carrier. In China, as in Southeast Asia, they’re also able to see it as a fruit. They don’t mind a fruit that looks like a vegetable or using it both for sweet and savory outcomes.

TWILLEY: In fact, Brook says that in the southernmost part of China, near the border of Myanmar, avocado is already popular. It’s used in salads with tomato and onion, like a kind of proto-guacamole. And it also goes into shakes, where it gets blended up with condensed milk, sometimes with powdered chocolate added for good measure.

GRABER: This is pretty common around the world—you find avocado ice cream and avocado shakes. It’s only starting to catch on here—we still seem to think of avocados mostly in savory dishes. But Brook says we can’t even imagine how big avocados are going to get in China. The avocado’s journey from Mesoamerican backyards to world domination still has a way to go.

LARMER: One of the guys that I quoted in the piece, this guy Steve Barnett who’s one of the biggest distributors in the world, dreams like every entrepreneur of introducing four chunks of avocado in every bowl of noodle soup in China.

MUSIC

TWILLEY: But wait, there’s more—what about the new pitless avocados? And avocado hand? And the trendy new variety that is supposed to be better than the Hass, and I want to plant in my back gardenz, but is impossible to get hold of, it’s so hot?

GRABER: Well, you can find out about all of that if you are one of Gastropod’s special supporters and get our special supporter newsletter! Every episode, it’s full of fun stuff we just couldn’t fit in. It’s $5 bucks per episode donation on Patreon, or $9 bucks a month support on our own website, gastropod.com/support.

TWILLEY: Thanks this episode to Brook Larmer, freelance journalist, avocado fancier, and New York Times Magazine “On Money” columnist, and also to Lauren Oyler, freelance journalist and avocado toast aspirer.

GRABER: As well as to Mary Lu Arpaia and Eric Focht of UC Riverside and Luis Mario Tapio Vargas at the Mexican National Research institute for Forests and Agriculture. We have links to their articles and publications and websites on our website, gastropod.com

POST-ROLL

This is a transcript of the Gastropod episode Cutting the Mustard, first released on February 27, 2018. It is provided as a courtesy and may contain errors.

ROSE EVELETH: So I’m Rose Eveleth. I’m the host of Flash Forward, which is a podcast about the future. But more importantly I am a very huge fan of mustard.

CYNTHIA GRABER: And you and I were actually talking about this, I don’t know, a year or two ago, and you were, like, you have to do an episode on mustard! So why are you obsessed with mustard?

EVELETH: So it’s funny—in thinking about this call we were going to have, I figured you would ask me that question and I realized that I don’t have a great answer. I mean it is objectively the best condiment. But that’s not the best answer. I mean it’s just really delicious, it goes on everything. But I wanted you all to do an episode on it because I am a fan of mustard and I consume a very large quantity of mustard, probably an embarrassing amount of mustard, but I don’t actually know that much about how mustard is made. Like, I’m familiar that there is a mustard plant and a mustard seed. But what actually makes different mustards different is actually sort of a mystery to me. I just eat them. I don’t know that much about them.

NICOLA TWILLEY: That’s what we’re here for, is to do the Googling that you can’t be bothered to do.

EVELETH: Exactly. I’m too lazy, I need an episode of Gastropod.

TWILLEY: Fortunately, Cynthia and I are not lazy at all ever in any way.

GRABER: I hope everyone believes you.

TWILLEY: And so Rose’s wish was our command. I’m Nicola Twilley.

GRABER: And I’m Cynthia Graber, and, as Rose pointed out, this is indeed an episode of Gastropod, the podcast that looks at food through the lens of science and history. We are happy to look into mustard, but Rose, in return you have to answer all my questions about what life might be like in the future. But first, mustard, what do you want to know?

EVELETH: I guess, you know, I eat a lot of mustard and I know a lot about the different kinds of mustard that I could purchase on the market, right? I know the, you know, various varieties of consumer goods related to mustard. I know a lot about how mustard tastes. I know nothing about the pre-going into my mouth parts of mustard. I mean I get the basics—there is a seed. You know, it’s like it’s in many ways like a lot of other things that are made from seeds. The powder seems obvious to me, right? It’s like ground-up seeds. Maybe I’m wrong about that. Who knows? You know, actually.

TWILLEY: Side note, which we didn’t say because we didn’t want to puncture Rose’s belief in all things Gastropod, but we didn’t actually know. Then. Now we do!

(PRE-ROLL)

(MUSIC)

GRABER: Rose has been a mustard fan for a long time.

EVELETH: I used to be an athlete in, like, high school. And so I was constantly at various athletic events and they often would sell pretzels and hot dogs and stuff like that. And I think that was when I realized that mustard is far superior to ketchup. And so I was always really into mustard. But I don’t actually know that much about, like, what the process is to take a mustard plant, and if there are, like, multiple different kinds of mustard plants, and that’s how we get these various different kinds of mustard. Like what makes Dijon, Dijon? Is it the plant, is it the seed, is it the processing? Is it some combination of all of those things? And so I was just curious about what where mustard comes from and sort of how all of these different types of mustard are made.

TWILLEY: So many questions! So many answers! But let’s start by getting our basics down: what exactly is this mustard plant of which Rose speaks?

PATRICK EDGER: So the mustard family actually consists of about 3,600 different species and so there’s quite a bit of diversity. Most of the species are the types that you would see growing in the cracks of sidewalks.

GRABER: Patrick Edger is assistant professor of horticulture at Michigan State University.

EDGER: The mustard family really consists of, you know, lots of wild species, but most notably the majority of the vegetable crops that you probably eat and consume every day. You know: broccoli, cauliflower, Brussels sprouts, kale, radishes, as well as like wasabi as a condiment or mustard as a condiment. But in addition there’s a lot of oil-seed types. So we would have things such as, like, rapeseed or canola oil that we would cook with. Those are all from the very same family.

TWILLEY: Fortunately, for the sake of my sanity, the kind of mustard that we can buy in the store labeled as mustard only comes from three plants within this enormous family: black mustard, brown mustard, and white mustard. Confusingly, the white seeds make yellow mustard, and the brown seeds are a kind of beigey-yellow inside, so the whole color terminology is not particularly helpful. But all three kinds of mustard seed have one thing in common: they’re tiny.

GRABER: And this is just the point of another mustard story Rose told us.

EVELETH: Yeah, so my grandparents on my mom’s side are Catholic and when I was a kid my grandma gave me this charm bracelet. And it had all sorts of various Catholic charms on it, it had obviously a little cross but it also had a bunch of other little charms that were relevant to various parts of the Bible or stories or whatever it was. And I was a very, like, tomboy kind of kid so I was, like, I’m not going to wear jewelry, this is stupid. But there was one charm on the bracelet that I was really into because it was this tiny little magnifying glass that you could flip open and you could look into it. And it just magnified one mustard seed. And I guess this comes from a parable of the mustard seed in the Bible.

GRABER: I had never heard of this parable of the mustard seed before—probably because I’m not too familiar with the New Testament.

TWILLEY: Whereas I had, despite never consciously listening in church at school.

CLIP OF MAN READING FROM THE BIBLE

EVELETH: Yeah, so I should say that I’m not a scholar of the Bible and nor am I a believer. So, like, I’m not an expert here. But it’s basically about how the mustard plant is really large—they can get to be nine feet tall. And for a plant that big they have small seeds. And so the story, the parable in the Bible, is kind of about that size difference—that when that tiny, tiny seed is planted in the earth it makes a giant plant. It’s kind of one of those “don’t judge a book by its cover,” I think, ideas—that even though the seed is so small it can become this great huge beautiful thing with birds and, you know, branches and all this stuff. So that’s kind of, I think, what the parable is about—if I’m interpreting it correctly, which I could be not doing.

TWILLEY: I am not a believer or a Biblical scholar either, but, from the best I can tell, this mustard seed story is actually more about how the kingdom of God will grow from its tiny beginnings.

GRABER: Which I still don’t really get, but that’s fine. It’s not meant for me.

TWILLEY: But this Jesus connection has an interesting side note attached to it. Supposedly because Christians were so attached to their mustard seeds, they carried them with them and scattered them as they walked, and so mustard plants grew along their trails. One of the places you hear about this happening is in California. People say that one of the early missionaries, Junipero Serra, walked north from the San Diego mission in the 1700s, scattering mustard seeds as he went. And the resulting quote “Bible trail” is apparently still marked by mustard plants today.  People say the same thing about pilgrim routes on the east coast of the U.S. too. You’re supposed to be able to see them clearly from above, thanks to their bright yellow flowers.

GRABER: There’s a Gastropod fan and supporter who happens to—okay—be a friend of yours Nicky, AND he also happens to work for a company that specializes in satellite mapping. So we figured, maybe he’d know if this supposed mustard trail is indeed visible from space. Do the satellite images show the particular visible signature of mustard?

TWILLEY: So my friend Wayne does actually have a real job, so he could not devote too much time to the search, but he told us that unfortunately, most purchasers of satellite imagery actually want something called “leaf-off images”—these are images captured in the winter where there isn’t a ton of foliage covering up all the other features they’re interested in. So, long story short, no luck.

GRABER: If anyone knows whether this California mustard trail tale has been proven true or false, please get in touch!

TWILLEY: But Rose doesn’t love mustard for its religious connections. She loves it because of its heat—its pungency and flavor.

EDGER: That sharp, pungent, bitter flavor that we sense are from compounds called glucosinolates. There are roughly a hundred and twenty-some different compounds and depending on the abundance and the profile of, like, the composition of these various compounds, that’s what gives cruciferous vegetables that sort of flavor.

GRABER: Now remember, these cruciferous vegetables—there are a lot of them: kale and Brussels sprouts and broccoli, just to name a few of my favorites. They have some of these glucosinolates—maybe slightly different ones with slightly different flavors. But things like kale and cabbage don’t have nearly as much pungency as mustard does.

TWILLEY: In other words, there’s a whole spectrum of spiciness between species, depending on which and how much of those 120 different glucosinolates they have.

GRABER: But here’s a question: What purpose does this pungency have for the plant?

EDGER: Yeah, so like most organisms plants do not want to be predated on. They don’t want to be consumed. And being a plant when you’re fixed in a location and you’re constantly combating insects and fungal pathogens and bacteria and viruses, you have to have some way to defend yourself. And so most of the flavors or things that we describe as flavors are actually chemical compounds that plants used to ward off being predated upon. And glucosinolates are one of those examples.

TWILLEY: Unsurprisingly, there’s an evolutionary reason for why the seeds of a mustard plant—the part we use for making the condiment—are much spicier than its leaves, which we use in a salad.

EDGER: If the purpose of a plant is to pass on their genetic material, they will invest quite a bit of that into their seeds to protect actually that next generation. So in mustard seeds, there’s lots of glucosinolates.

GRABER: These glucosinolates are really poisonous to some species—they kill insects.

EDGER: Glucosinolates are actually incredibly toxic even to the plant. The plants will actually sequester a lot of the precursor molecules in vacuoles that safeguard it even from the cell. So that’s how toxic they are.

GRABER: Those special containers get broken open when an insect starts chomping.

TWILLEY: But here’s where these mustard toxins gets even more interesting. A couple of years ago, Patrick published a paper tracing what he calls the great butterfly-mustard arms race. The story starts 90 million years ago, when the first mustard plant ancestors figured out how to stop caterpillars from eating them—by producing some glucosinolates.

EDGER: When the compounds first evolved, it would have been an instant barrier for predation, right? And so that actually would have permitted that ancestral plant that just evolved this novel trait to diversify very rapidly across the landscape. Because now it basically has a wonderful sort of set of armor for any predation to occur.

GRABER: So now the mustard great-great-great-etc. grandparent is super chill. The caterpillar can’t eat it, it’s free to grow and spread across the landscape. For at least a few million years.

TWILLEY: But the caterpillars aren’t done. They are hungry, hungry caterpillars.

EDGER: So the insects evolved a enzyme, a novel enzyme, a brand new gene, that actually, as the insect is consuming these glucosinolates, actually cleaves the compounds—this chemical compound—to make it an inert structure.

GRABER: So now these glucosinolates are no longer toxic to the caterpillars, and now the caterpillars are the happy ones.

EDGER: We then see, as one would predict, it now has a buffet.

GRABER: They can eat as much as they want of this spicy plant that no other insect can snack on.

TWILLEY: And now it’s the caterpillar’s turn to spread and diversify and generally be boss. But, as you would expect, the mustard plant ancestor does not take this lying down. Like Patrick said, it’s an arms race.

EDGER: We actually see repeated cycles of this—minimally, three of them that have occurred over the last 90 million years.

GRABER: This is plant-animal warfare, people. For his experiment, Patrick and his colleagues studied hundreds of species of related plants—plants that trace their ancestry back to those original, millions-of-years-ago genetic splits. This way they could figure out the timeline of when each side temporarily was victorious.

TWILLEY: They could see these big leaps forward in mustard defenses written in the plants’ DNA. One thing to know: lots of plants pass multiple copies of their genomes down to their offspring, instead of the single copies that we humans pass on to our kids. And this extra genetic material gives the mustard plants so many options to play with—so many different pathways to make new, improved glucosinolates.

EDGER: After every set of duplications, you basically would have a new and fancier set of defenses. And this escalated over time until the present day where many of the mustard plants have, you know, over 100 compounds in them.

GRABER: Here’s one of my favorite points in this whole research: this arms race led to amazing success for both insects and plants. As the war went on, it actually created many, many new species of both brassica and butterflies. Both dramatically increased in biodiversity and habitat. It is at least partly due to this arms race that we have kale and collards and cauliflower and Brussels sprouts and horseradish and radishes and mustard and everything.

EDGER: As the brassicaceae were more successful, that actually permitted subsequently the butterflies to be more successful. But then they also each of them have shaped the underlying genomes or even the phenotypes of one another. Ultimately, we really have the butterflies to thank for mustards, right? Mustard compounds. None of this would have existed if it wasn’t for this arms race.

TWILLEY: Next time you squirt mustard on a hot dog, remember to thank a caterpillar. So that’s cool, but my favorite part of Patrick’s experiment is that as part of his whole process, he found plants that are living today that have the level of glucosinolates that mustard used to have in the past.

EDGER: There are actually relatives from those ancestral intermediates that you can go out and you could potentially sample. And that was part of the study. We found all these sort of intermediate lineages—remnants. And from that, we can actually make estimates of what those profiles probably were like. We can’t be very definitive about it but we can make really pretty solid estimates of what those ancestral states would have been like, going back to at least 90 million years.

TWILLEY: I temporarily lost my mind for a minute when I heard this and decided that what Cynthia and I needed to do was track down all these milder-tasting relatives and do a mustard tasting through evolution, from bland to fiery.

GRABER: That sounds awesome, of course, but then you realized that it’s just the two of us and we have to put out shows and that would take months of plant collection and seed crushing.

TWILLEY: But if some millionaire mustard-ophile out there would like to fund this quest, I am available to talk offline. The 90-million year mustard tasting awaits!

GRABER: And I will happily join in. So Patrick and his colleagues wrote about this butterfly-mustard arms race. But here’s something that might scare you: the battle is not yet over!

EDGER: We see this constantly happening. So a lot of cabbage butterflies, if you grow any cruciferous vegetables in your backyard—broccoli or cabbages or cauliflower or what have it—you’ll see lots of cabbage butterflies always trying to predate on it.

TWILLEY: And that means that the plants need to be upping their game. And they will.

EDGER: I could imagine a mustard being spicier.

TWILLEY: Not just spicier, but even with a slightly different flavor profile, from new variations and combinations of these glucosinolates. Basically, we can’t even imagine the mustards of the future!

GRABER: Rose, this is the episode you get to make!

TWILLEY: Right, you do mustards of the future, we do the mustard science, and, next, mustard history.

(MID-ROLL)

HAYLEY SAUL: At this stage, I would say that these findings are the earliest conclusive use of spice for a culinary purpose.

GRABER: Hayley Saul is an archaeologist at Western Sydney University. And, a few years ago, she and her colleagues discovered the earliest known example of spiced food in human history—dishes perked up with, yes, mustard.

TWILLEY: OK, picture the scene. It’s more than 6,000 years ago, and you are in northern Europe, eating a plant called garlic mustard.

SAUL: So there were three main sites where we found the evidence of garlic mustard. One of them in Germany, which is a site called Neustadt, which is actually now underwater. It’s been excavated underwater. That inundation is actually one of the reasons why the pottery and the pottery residues are very well preserved because the waterlogging is great for preservation. And the sites in Denmark—so the sites are called Åkonge and Stenø,and they’re located on the edge of a bog.

GRABER: There are a lot of sites like these found near water, because water is a great source of food. But the people who were living at these sites, were they just hunting and gathering all the wild plants and animals that lived in and near the water? Who were these people?

SAUL: So, you know, all of the sites actually span the sort of Mesolithic/Neolithic transition, which is the time at which people were starting to just domesticate and experiment with domesticated plants and animals. So the people that lived kind of in the Mesolithic tend to be associated with hunting and gathering. But it’s actually much more complicated than that, really. It wasn’t the case that people just gave up on hunted and gathered foods and then adopted these new, more superior types of domesticated foods. They were actually combining things and it was just a period—I like to think of it as a period that was very creative. And there were new types of food coming in but people were starting to sort of explore how they can combine it with food that they’d used for years.

TWILLEY: What Hayley’s saying is surprising to me. I don’t tend to think of Mesolithic or Neolithic people as being culinary wizards or experimenting with their food to create new textures and flavors.

SAUL: I think there’s been a kind of an assumption in general that in prehistory, people were driven by just the need to get a certain amount of energy and that there was nothing particularly artistic about food practices in prehistory. And in part that’s brought about just because of the techniques that we have and the difficulty of finding certain evidence. So it’s quite easy to document animal bones on a site and slightly more difficult to document plants because they don’t preserve very well.

GRABER: In the past, scientists have been able to figure out what people were eating on a kind of more general scale—did they get more of their calories from protein or from fat, did they go fishing, or were they butchering domesticated cattle? But, until recently, it’s been much more difficult to get a fine-grained look at the flavors of the foods prehistoric peoples were cooking. But now, there are new techniques that Haley says can give a higher resolution look at ancient diets.

TWILLEY: These higher resolution techniques include starch analysis, as well as drilling into food residue to analyze the fats. There’s also a kind of microscopic analysis to match the tiny fossil remnants of plant cells, which are called phytoliths, to a catalog of different plant species collected from the area. The combination of all these techniques, plus how well preserved the food residues were at these sites, meant that Hayley and her colleagues were able to get that more nuanced and detailed picture of what these early northern Europeans were eating.

GRABER: And there was a lot of food residue for Hayley and her colleagues to analyze.

SAUL: In some cases it was up to a centimeter thick, because the pottery wasn’t necessarily cleaned. So it was just becoming more and more carbonized, and thicker and thicker residues. A bit like you would use a skillet, the flavor is partly brought to the food because the skillet is sort of reused again and again and again. And it’s only when the carbonization of that residue becomes so distasteful that the pottery is actually thrown away into the lake or into the sea. And at that point, it’s just like a record of reuse and a kind of build-up of all of these different meals that the pots been used for.

GRABER: And Haley’s big find from this food residue? These Mesolithic people were revving up their stews with a plant called garlic mustard. I know I said this already, but—drumroll!—this is the earliest known culinary use of a spice in the world.

SAUL: It’s from the seed husk, the actual sort of hardened shell of the seed, which has a flavor, if you grind it up, much like mustard.

TWILLEY: Hayley was able to figure this out by comparing the phytoliths—these plant micro-fossils—to the microscopic structures you find in garlic mustard today.

SAUL: I had to do a lot of just going out into the countryside and foraging for plants that were edible and, you know, making up the reference collections and things. And it’s one of those plants that you could so easily overlook. It’s just everywhere. And once you get your eye in you can see that it’s everywhere. It’s a plant that’s available across the whole of Europe, right into India and parts of Asia as well. But it’s not just usable for the seeds. The leaves of the plants are edible as well. The reason it’s called garlic mustard is because the leaves have a very garlicky aroma but the seeds have a very mustardy flavour. So you can sort of combine two different flavors in one plant really.

GRABER: That sounds delicious. But we were wondering—maybe garlic mustard was a major source of calories for the folks in these settlements. How can we know it was being used intentionally to flavor their food?

SAUL: The seed itself of Alliaria petiolata is very small and it’s woody. Some people have suggested that it has properties for preservation. It may have medicinal properties. But, because it’s so woody, in terms of delivering anything like energy or a great deal of vitamin nutritional value, it doesn’t really do that. So it seems to be much more that it’s being used at least in part because of its aromatic properties. So it is imparting flavors into the food.

TWILLEY: Basically, it turns out that Hayley is pretty confident that Mesolithic people had Rose Eveleth-style levels of enthusiasm for mustard. They too thought that there was nothing that didn’t taste better with some mustard!

SAUL: So we were finding from the lipid residue analysis that they were combining garlic mustard with marine fish.

GRABER: They also made stews of garlic mustard and meat from animals they either hunted or raised, like cattle or deer.

SAUL: It’s such a common spice it’s almost like they’re using it as we would use salt and pepper. And that suggests to me that it could have an even longer history. But we just don’t know at this stage.

GRABER: And actually, there are even older sites around the Mediterranean that have plant remains from other spices and herbs—poppy, cumin, and coriander—but the plant bits are not embedded in cookware. So we can’t be positive that people were actually eating these spices. But maybe they were.

TWILLEY: Really, though, the important question here is, what did these mustard-spiced dishes taste like? Fortunately, Hayley can answer that one too.

SAUL: Because my research involves me sort of going out and foraging for plants for my reference collection, the temptation is always there to try out what the flavors of those different plants were, yeah, so I have made some unusual concoctions of my own. But if you can find some garlic mustard, just grinding it up in a pestle and mortar and you can smell the mustardy flavor as you’re grinding it as well. And it’s delicious in a nice stew.

TWILLEY: Yes, that’s right: Hayley made her own Mesolithic garlic mustard stew.

SAUL: I used it with some venison. My dad’s a butcher, so I managed to get a nice cut of venison.

TWILLEY: And?

SAUL: It did taste quite contemporary. It’s not such a strong flavor as the sort of mustard that you would get in a pot. But there is definitely a sort of flavor of mustard.

GRABER: I love the idea that the earliest known use of spice involves garlic mustard. Two delicious flavors in one plant. But, for Hayley, even more importantly, this finding helps us rewrite the stories we tell about the people who were alive back then.

SAUL: It’s easy to fall back on the idea that people were sort of caveman-like and, you know, they were just out to sort of eat as much and as often as they could because they never knew when their next meal was, and things. But actually I would say that they were extremely sophisticated, and they had such sophisticated skills at acquiring food that they could sort of be really creative about the ways that they were combining foods.

TWILLEY: This is another thing that Rose and our Mesolithic friends have in common: mad mustard-pairing skills.

EVELETH: I put it on everything. I mean, I’m a big carb person. So, like, any kind of bread product, it’s good on. Olive bread with mustard is extremely delicious. I mean, obviously there are pretzels, but you can also put mustard powder on things like popcorn. So, like, a little bit of soy sauce and mustard powder on popcorn is delicious.

GRABER: I’d love to try that popcorn. But so I was wondering, you know, can you walk us over to your fridge? Tell us about how many jars you have and could you list some of the ones that you see?

EVELETH: Yeah. All right, I will—I’ll take you over. Hopefully my dog doesn’t get too interested in what we’re about to do. Okay, I’m opening the fridge. Let’s see, where are we. So there’s this great mustard place called—I’m going to mispronounce it. Maille? Maille? M A I L L E. Okay, so we have a bunch of those. I have a walnut mustard from them. I have a Dijon blackcurrant liqueur mustard from them, which is really good. It’s like—it tastes like Thanksgiving. It’s amazing. Really good on French fries actually, because, like, they’re sort of a good vehicle for any kind of mustard but they taste like Thanksgiving French fries. I have a blue cheese mustard which is super strong. You kind of have to, like, be a little gentle with this one. We also have an amber ale honey mustard from this farm up in Vermont that is near a place where we go skiing every year. We, of course, have sort of the standard spicy brown for sort of hotdogs and all that stuff.

TWILLEY: There’s more—many more jars. The thing is, it’s not just Rose that’s crazy about mustard. Her partner Robert is too. It’s actually central to their whole relationship, at least in terms of condiments.

EVELETH: We have a running joke, because I subscribe to the Mustard Museum’s newsletter, and it’s sort of full of mustard information. And a couple of years ago, they sent one out and that was, like, you know, we do weddings. And I don’t know if they were serious or not but we have a running joke about getting married at the Mustard Museum.

GRABER: Nicky, you and I did not have wedding plans.

TWILLEY: Because we’re already work married.

GRABER: But we did actually visit the Mustard Museum. It’s just outside Madison, Wisconsin, and we happened to be in town to do a Gastropod live show. When in Madison, go see mustard, apparently.

BARRY LEVENSON: So anyway we’re going down into the museum: the world’s largest collection of mustard, mustard memorabilia, and fine mustard art.

TWILLEY: Barry Levenson is the founder and curator of the National Mustard Museum. He’s a lawyer with a serious mustard obsession.

LEVENSON: We’ve got nearly 6,000 different mustards here. So, in addition to American yellow mustard, classic French mustard, you have horseradish mustard, you have whole grain mustards. We have hot pepper mustards. We have herb mustards, we have fruit and vegetable mustards. We have garlic mustard. We also have spirit mustards, which would be mustards made with beer, with wine. We have exotic mustards. The exotic mustard category can be anything from curry mustards to truffle mustards to mustards with ginger. Right now, we’re standing in front of some of the French mustards.

TWILLEY: But before things get even more insane—although personally I think getting married at the mustard museum is already pretty insane, and having 6,000 jars of any condiment is definitely a warning sign—we need to back up. How did we get from garlic mustard seed stew to the condiment-filled jars we know and some of us love today?

GRABER: Before we clear your sinuses with some strong Dijon, we have a sponsor to tell you about.

(MID-ROLL)

GRABER: To get to France, first we have to go back to ancient Egypt.

LEVENSON: We also know that the ancient Egyptians would chew mustard seeds along with their meats and that would flavor it. But they would just take the seeds, because mustard seeds themselves are inert.

TWILLEY: There’s actually a chemical trick to mustard. So: the glucosinolates in mustard seeds—they’re slightly different compounds in black vs. yellow vs. brown mustard seeds but they work the same way. Which is that they they react with a particular plant enzyme in the presence of cold water to produce that fiery essential oil of mustard. This multi-step trigger process is another way that the plant holds fire until the caterpillar actually crunches into it and sets off that reaction.

LEVENSON: It’s only when combined with some liquid do they release their heat and their pungency. As a result, that’s what the Egyptians would do. They’d say, okay, have some meat and chew on some mustard seeds.

GRABER: Then the Romans decided to turn mustard into a sauce.

LEVENSON: We know that the Romans were using mustard seeds in some of their sauces and then that migrated into the Roman Empire, specifically into the area now known as Dijon, where the monks were making pretty much what we know as mustard today back in the 12th and 13th centuries.

TWILLEY: The first reference to mustard in the Dijon archives occurs in 1336—it’s a record of a whole cask of mustard being consumed at a banquet. So mustard was already a big deal. The first ordinance specifying how to make Dijon came at the end of that century. Basically, soak the seeds, crush the seeds, and then add vinegar to the paste. To go back to our chemistry for a minute, using an acidic liquid like vinegar puts a brake on the reaction, which gives the resulting mustard a long-lasting, slow burn—as opposed to the quick, pungent hit of mixing it with water.

GRABER: Dijon mustard got super popular in 1756. That’s when a major mustard maker in Dijon changed his recipe from vinegar to verjus—it’s a juice made from unripe grapes, and it’s not quite as acidic as vinegar. Today, if you buy Dijon mustard, it doesn’t usually have verjus, but the makers still try to make it taste like the recipe that made it famous. They’ll often use a combination of white wine and vinegar.

TWILLEY: Technically, Dijon is supposed to only be made with either black mustard or brown mustard seeds. But basically nobody uses black mustard commercially because the seed heads are so fragile that you have to harvest it by hand.

GRABER: Seventy to eighty percent of the mustard seed exported to make condiments comes from industrial fields in Canada, which happens to be the world’s mustard basket. And Barry says a lot of those mustard seeds go to France.

LEVENSON: France, of course, is known for mustard. The per capita consumption of mustard in France is greater than any other country.

TWILLEY: Since the 1800s, Dijon has been found at tables throughout France. In my home country, though, we developed a rival: Tewkesbury mustard, which is mustard mixed with its close cousin, horseradish, for a little extra something something. This mustard was sold and transported dry in balls, known as Tewkesbury fire balls. They were a staple in English kitchens in the 1600s.

LEVENSON: Shakespeare loved mustard and wrote about mustard in several of his plays.

GRABER: Shakespeare even used this famous Tewkesbury mustard in one his slightly less famous plays, King Henry IV Part 2. He wrote, “His wit’s as thick as Tewkesbury mustard.”

TWILLEY: This is not a compliment.

GRABER: Barry has his own favorite Shakespearean mustard quote.

Barry: “What say you to a piece of beef and mustard? Aye, a dish I do love to feed upon,” from Taming of the Shrew.

TWILLEY: Here’s the Shakespeare mustard reference I found surprising though: eye of newt, which is one of the things the witches stir into their cauldron in Macbeth—”eye of newt and and toe of frog, wool of bat and tongue of dog,” etcetera, etcetera. So eye of newt—I always thought that was the eye of a newt. But it isn’t! It’s an old name for a mustard seed.

GRABER: Rose, the rabbit holes you’ve sent us down! But Shakespeare’s Tewkesbury isn’t the most famous British mustard today.

LEVENSON: That would be Colman’s. The classic hot, just good, strong mustard that just kind of goes right up in the nose.

TWILLEY: Colman’s in the yellow tin—it’s *the* British mustard.

LEVENSON: Yeah, Colman’s dry is kind of the gold standard.

TWILLEY: The thing about Colman’s is, as Barry points out, it was originally a dry mustard—and you can still buy it that way today. I have two tins of Colman’s mustard powder in my kitchen as we speak. But grinding and selling dry mustard as a powder—that actually wasn’t Jeremiah Colman’s idea.

GRABER: The inventor of powdered, dry mustard is lost to history. The only record comes from an article published in 1807, in the Gentleman’s Magazine. And the author wrote that, in 1720, quote, “it occurred to an old woman of the name of Clements, resident at Durham, to grind the seed in a mill and to pass the meal through the various processes which are resorted to to make flour from wheat.”

TWILLEY: Ms. Clements’ mustard flour was a huge hit. Even George the First gave it the thumbs up. But she kept the secret to herself for many years. Jeremiah Colman was originally a flour miller, with a mill of his own. He didn’t turn to mustard until nearly 100 years after Ms Clements’ big breakthrough. But then he conquered the British mustard market, with a special blend of locally grown white and brown mustard seeds ground to a fine powder.

LEVENSON: Colman’s mustard was just dry mustard for the first 60 or 70 years before someone decided at Colman’s, well, why don’t we actually make the mustard condiment?

GRABER: So while Dijon is made from brown mustard seed, Colman’s is a blend of white mustard and brown mustard seeds. Brown seeds, like the ones used in Dijon mustard, they give you more of a horseradish-y, sinus hit.

LEVENSON: It gives you more of that nose hit as opposed to the yellow seed, which is more pungent just on the tongue.

TWILLEY: So France has its favorite mustard, Dijon, England has Colman’s, but in America, it’s all about French’s. So what’s that?

LEVENSON: That came about a little over 100 years ago, when Mr. French decided that even though there were European mustards, they weren’t all that popular. What this country needed was a brightly colored, happy mustard and that’s what French’s mustard has been.

GRABER:  Actually French’s mustard—it first came out at the turn of the last century—it was originally called “French’s Cream Salad Brand.” Not only was it bright yellow because Mr. R. T. French added turmeric to the recipe, but it was also creamier and sweeter. And it was a huge, huge hit almost instantly in America.

LEVENSON: It is generally made with the yellow seed, so it is going to have a very different kind of flavor profile. And that’s the kind of thing that when you go to the ballpark, I think you’ve got to have yellow mustard at least on that first dog. Because you hold up the hotdog, you know, and you see the blue sky, the green grass, the brown base paths and there’s just something about that yellow squiggle of mustard that makes life so worth living that day.

GRABER: Oh Barry.

TWILLEY: People have strong feelings about mustard.

MADHUR JAFFREY: It’s very important and it’s an ancient seed that we’ve had forever.

GRABER: Madhur Jaffrey is an actress and food writer. She’s probably the most famous writer of Indian cookbooks—she’s the person whose cookbooks helped popularize Indian cooking at home in the West.

TWILLEY: We’ve been stuck in Europe and America so far this episode, but mustard is global. And India has its own serious, long-term mustard thing going on. It’s not a condiment-based relationship, but it’s central to Indian cuisine

JAFFREY: It’s been amongst our two hot spices that originated in India. We started out thousands of years ago with mustard seed and black pepper. Those are native to the region and those were the only spices we had that were hot, and chiles of course came much later. So for many centuries, they were even more important than they are today, but they’re still very important today, because one of the oils that we cook with, which is very important, is mustard oil.

GRABER: Mustard seed and, even more importantly, mustard oil is found in kitchens throughout the Indian subcontinent.

JAFFREY: It’s used for cooking a lot of food in several states. Bengal cooks a lot with mustard oil. Kashmir cooks a lot with mustard oil. So these are two states where it’s almost the state oil. And there are certain dishes that would be cooked always with mustard oil. If you’re steaming a fish, you will definitely use some mustard oil. In Bengal, if you are making this muri, which is puffed rice, you’ve puffed it and then you want to dress it quickly with different things, you’ll put, among other things, mustard oil on it and have it for breakfast.

TWILLEY: So but here’s what’s weird. Mustard oil is banned in the U.S. as a food. It has been since the 1990s.

JAFFREY: When I buy mustard seed oil, it says on top: “Use for external purposes only.” People in India eat it and survive and nothing happens to them and they live long lives. We put it on babies, we—you know — but externally we put it on babies. But I keep reading it and ignoring it. It’s just like what they used to say with coconut oil. “Don’t cook with coconut oil.” And people go through fashions and suddenly now everybody is cooking with coconut oil as if it’s the best thing in the world.

GRABER: You might think that maybe the U.S. government was afraid of those pungent, insect-fighting glucosinolates. But no. The FDA thinks the problem comes from a fatty acid that’s found in the seed. Apparently tests on rats show that in high doses this particular fatty acid can cause heart lesions. But frankly, as Madhur says, literally billions of people have been cooking with mustard seed oil for thousands of years.

JAFFREY: I wouldn’t give it up. No. It is in a lot of things that I cook. I cook everything from all over India and I use it all the time.

TWILLEY: For Madhur, the magic of mustard is in the way you can manipulate its heat.

JAFFREY: It’s like a Jekyll and Hyde of both spices and oils. If you use it plain, it’s quite pungent. So when we want that pungent flavor, we use it plain. But if you heat the oil or if you pop the mustard seeds, they turn sweet and nutty. So it depends on what we want. It can change its shape, as it were.

GRABER: So in India, cooks know that cooking heat tames the fieriness of mustard seeds and oil. But Barry says condiment markers can use other tools to manipulate that heat, too.

LEVENSON: Which seed you use, how much water, how much vinegar is going to be used. There are all kinds of ways that mustard makers are able to change the heat of the final product.

TWILLEY: In fact, mustard is surprisingly nuanced. You think of it as this blast of heat on a sandwich, but, depending on how you make it or how you pair it with food, mustard doesn’t have to steal the show—it can fade into the background and just make everything else taste better.

GRABER: I never really had strong feelings about mustard one way or the other, unlike all of our guests this episode, but the bagel shop near me uses mustard butter on their bagel-egg sandwich and it’s mind-blowing. So I also started using a layer of mustard in my savory galettes—these are free-form pies—and it totally ups the game.

TWILLEY: Whole-grain mustard smeared inside the pastry shell of a quiche, before you add the filling: unreal. And mustard powder is my secret ingredient in cheese straws. But Barry and Rose have taken this pairing game a little further.

LEVENSON: It’s something that you can also use in brownies because it accentuates the flavor of chocolate.

EVELETH: This is going to sound disgusting to a lot of people but I think it’s delicious: a little bit of mustard on Oreos is extremely good.

GRABER: Wow, that is an unusual one.

TWILLEY: Wait, wait, wait so are we talking like French’s here or what are you doing? Like, how is that?

EVELETH: Like you sort of dip a double-stuffed Oreo into like, a little bit of mustard, in Dijon mustard.

GRABER: And what does that do for the Oreo?

EVELETH: Well, because the Oreos are so sweet, right? Like, you’ve got the chocolate cookie and then you’ve got that, like, really saccharin middle chemical bit—like, I don’t know what it is—

GRABER: The white part.

EVELETH: The white part—it’s so sweet that just a little bit of like spiciness or that little bit of, like, mustard flavor is really a good foil to the Oreo. It’s delicious. I know everyone listening is going to be, like, you’re a psychopath. But I love it.

GRABER: I totally want to try this.

EVELETH: It’s really good.

TWILLEY: I might skip mustard Oreos. But I’m much more into Rose’s most recent mustard revelation.

EVELETH: I have been really into making Bloody Marys recently, and I put a little bit of mustard in my Bloody Mary mix.

TWILLEY: Wait, the spread or the powder?

EVELETH: So I’ve been experimenting with both. So I will put a little bit of powder in the ring, like, the ring that you put on the glass.

TWILLEY: Oh yes, that does sound really good.

EVELETH: And then a tiny bit of it in. Yeah, it’s super good. You have to be careful because you could definitely overdo it with mustard powder particular. But I also put a little bit of Dijon in the actual sort of concoction, the tomato paste concoction that I used to make Bloody Marys. I’ll make you Bloody Marys any time, they’re my favorite drink and I’m really into making them.

GRABER: I’m so there!

TWILLEY: And that’s it for today’s episode because we have somewhere to be! There is a mustard Bloody Mary calling my name.

(MUSIC)

GRABER: Thanks this episode to Rose Eveleth. She is the host of a fascinating podcast called Flash Forward—it’s all about possible and not so possible futures. She had a recent one on a future where we’re all telepathic, and another scary and possible one about what happens if the census goes haywire.

TWILLEY: Thanks also to Patrick Edger of Michigan State University, Hayley Saul of Western Sydney University, and Madhur Jaffrey, legendary food writer and actress. We have links to their work on our website, gastropod.com. And, finally, thanks to Barry Levenson of the National Mustard Museum in Middleton, Wisconsin.

GRABER: We’ve got some more fascinating mustard stories involving mustard gas, mustard plasters, and mustard sounds saved for our special sustaining supporters newsletter: if you’re able to donate $9 a month on our website or $5 per episode on Patreon, you too could enjoy some more mustardy goodness!

(POST-ROLL)

GRABER: We’re back in two weeks with a few famous friends. Yep, we’re hanging with Nigella and Yotam and we’re name-dropping like we just don’t care!

This is a transcript of the Gastropod episode Secrets of Sourdough, first released on December 19, 2017. It is provided as a courtesy and may contain errors.

CYNTHIA GRABER: That’s really good.

NICOLA TWILLEY: Really good. That’s good.

GRABER: One more—I know, I just need one more little bit.

TWILLEY: Just one more piece.

GRABER: I’ll join you in that.

TWILLEY: How can I not? It’s so good.

GRABER: It’s so warm and yummy. I’m going to taste some of this. Mmmm, Nicky—hot pita with garlic butter?

TWILLEY: Welcome to an episode of carb lovers anonymous!

GRABER: Not so anonymous. Nicky, they know who we are. I’m Cynthia Graber—

TWILLEY: And I’m Nicola Twilley, and this is actually Gastropod, the podcast that looks at food through the lens of science and history. And Cynthia and I are the not-so-anonymous carb lovers.

GRABER: We spent three days in Belgium with two scientists and more than a dozen bakers. We were in theory investigating a deep scientific question about bread—but actually

TWILLEY: We were eating our body weight in bread. And Belgian waffles.

GRABER: Nicky, I still am not sure I can forgive you for encouraging me to eat that second hot Liege waffle—I felt a little sick afterwards—but it was frigging amazing.

TWILLEY: Listeners, I ask you: was that a bad thing that I did? No. When in Belgium, eat the Liege waffles.

GRABER: But you’re not here to find out how many pieces and what types of bread we gorged ourselves on in a 72-hour period. You want to know what we wanted to know: all about sourdough. In fact, many of you have written us emails asking us to do this very episode. For instance, listener Alex Freedman, who lives nearby in Somerville but grew up in San Francisco, wanted to know about the history of sourdough. Alex, we’re on it.

TWILLEY: Listener Danae Garriga is northern Illinois requested an episode devoted to sourdough starters. As a baker, she’d read about wild yeasts and how the environment the starter is made in affects the microbes in it. And she wanted to know, if she gave some of her sourdough starter to a friend, would the microbes in that starter change? Danae: exciting news, that is exactly what we went to Belgium to figure out, in the world’s most delicious science experiment. In fact, we have the world exclusive scoop on this brand new research!

GRABER: It’s true, we tagged along with scientists at the cutting edge of sourdough. The question they were trying to answer is: those microbes that make up your wild sourdough starter, where do they come from?

TWILLEY: Is it from the water, like so many people—especially in San Francisco—believe? Is it from the baker or the bakery?

GRABER: Or is it from the flour?

TWILLEY: This was a gigantic scientific mystery. Up till now.

GRABER: We are going to take you along to Belgium with us on this path of scientific sourdough discovery. But a quick note, if you’re a regular listener, you know we have a Gastropod drinking game: we say microbes, you yell, “drink!” and then, you know, do so. If you do that this episode, you’ll be drunk. Really fast.

(PRE-ROLL)

(MUSIC)

GRABER: This summer, Nicky and I traveled to a remote corner of Belgium. We were visiting the headquarters of Puratos, one of the world’s biggest bakery ingredients companies. They’d invited more than a dozen bakers from more than a dozen different countries to participate in a science experiment.

PAUL BARKER: Hi, my name’s Paul Barker and I’m from the U.K.

CHRISTOPH VÖCKING: My name is Christoph Vöcking, I’m from Germany.

JOSEY BAKER: My name is Josey Baker, and I’m from America.

STAVROS EVANGELOU: Hello, my name is Stavros, I speak English not good.

HAKAN DOGAN: I am Hakan, I’m from Turkey.

LETICIA VILCHIS: I am from Mexico. I am a baker too.

TWILLEY: And then there were also two scientists: Anne Madden and Rob Dunn. They work together in Rob’s lab at North Carolina State University. And they were meeting all these bakers for the first time too—to introduce the experiment.

ROB DUNN: We know that when you make a sourdough, the species and strains of microbes in that starter, they influence the nutrition of that bread, they influence the flavor of that bread. They influence every part of the bread. And yet it’s still pretty mysterious what determines which of those microbes are originally in your starter.

GRABER: Rob and Ann are microbiologists. They’ve been studying communities of microbes in all sorts of places—your bellybutton, your showerhead…

DUNN: And we’ve worked on microbes for a long time and often the responses is repulsion, like oh gross, there are microbes in my house.

ANNE MADDEN: When you talk to people about bacteria that might be in their bathroom it’s ugh, ugh, please stop talking, please don’t tell me any more. I don’t want to know. But when you talk to people about the microorganisms in their sourdough, it’s like, what did my children do? This is lovely. Like, can we put it on the refrigerator? Are there pictures? I love the response.

DUNN: And this was this one little niche where people seemed to gather around the idea that this was a beautiful kind of microbe, that there was something wondrous about them.

TWILLEY: And there really is something wondrous about a sourdough starter. It’s a community of wild microbes that somehow, miraculously, makes bread rise.

GRABER: And you need something to make the bread rise, because otherwise, if you mix flour and water and bake it together, you get matzah. Or, you know, a cracker. Hard and flat.

TWILLEY: Today, if I’m a baker and I want to make my bread rise, I can just go to the store and buy some baker’s yeast. Baker’s yeast is precisely one microbe, Saccharomyces cerevisiae, but it does the trick.

GRABER: But bakers have been making leavened bread in an oven—bread that puffed up and got soft like ours does today—people have been baking that for thousands of years. The ancient Egyptians made bread.

KARL DE SMEDT: So our question was okay, so where did the Egyptians bought their yeast? Because to make bread you need flour, water, salt, yeast. So where did they bought their yeast? They didn’t. It was there.

TWILLEY: This is Karl de Smedt. He’s the communications and training manager at Puratos, and, for this experiment, he was the one in charge of wrangling the bakers. And before we got started on the science, he dropped some sourdough history on the group.

GRABER: Nobody knows exactly where and when sourdough bread was first invented. The earliest evidence we have for making bread comes from a site in Africa. Archaeologists have dated the remains of that bread to about a hundred thousand years ago. It was probably made from pounded sorghum and water and baked on a hot stone.

TWILLEY: We’re not sure whether that was a sourdough or not—but it may have been something like the injera that Ethiopians still eat today. That’s sort of spongy and bubbly, and those bubbles are created by a community of wild microbes, just like today’s sourdough.

GRABER: Basically, if you combine ground up grains—something like wheat—with water, and you forget about it and leave it alone, eventually it starts bubbling. And that’s because a bunch of different microbes, usually a combination of fungi like yeast and bacteria like Lactobacillus, they colonize the mixture and feed on the flour and that is both the start of beer, and a sourdough starter!

TWILLEY: There’s hot debate among historians about whether humans first figured this out because they were making booze, or making bread. I am on team beer, to be honest, but short of Cynthia finally inventing her time machine, we will probably never know. Either way, humans figured that this wild bubbly mix made their flatbreads into breads—the non-flat kind. These loaves of bread would all have been sourdoughs. There was no other way to make bread rise.

DE SMEDT: So for thousands of years sourdough was being used by each and every baker or person that would bake bread.

GRABER: And even before people knew what microbes were, they were already caring for these wild communities of bubbling beige gloop, feeding them with more flour and water to keep them alive and happy. They figured out that you only need to add a dollop of starter to your dough to leaven it, which means you can keep the same starter going for years and years—decades even—just by feeding it with flour and water and using a little bit of it every time you bake. It becomes like your own personalized wild leavening mix that you can keep alive and use it again and again and again.

TWILLEY: Other people developed variations on this approach. In ancient Greece, for example, Pliny the Elder describes people saving a piece of their dough from the previous day to raise their bread the next day.

GRABER: Pliny also reported that people in Gaul and Iberia, otherwise known as France and Spain, they would use the foam they’d skimmed from beer to produce what he called “a lighter kind of bread than other peoples.” It’s the beer/bread question again—either way, it’s communities of microbes that grow on mashed-up grain-and-water mixes, and that have the power to both leaven bread and ferment sugar into alcohol.

TWILLEY: Over time, we figured out how to curate and stabilize these communities, so that they worked as expected, most of the time. Still, they were all a little different and a little finicky—my sour culture might make bread rise faster, yours might produce a better crumb, mine might all the sudden stop working.

GRABER: But these sour cultures were the only tool we had to bake leavened bread. And then everything changed.

DE SMEDT: And with the discovery of the microscope, with some research done by scientists, actually with Louis Pasteur, who wrote this Memoire sur la Fermentation Alcoolique, who opened actually the production of commercial baker’s yeast.

TWILLEY: It was two Hungarian born brothers, Charles and Max Fleischman, who first commercialized Pasteur’s insight. They started selling baker’s yeast—fresh yeast, sold in little cakes.

DE SMEDT: And it was such a convenient product that bakers embraced it with open arms. They all started to switch from that very inconsistent, complicated, long process that is sourdough towards something that is very precise, very accurate, very fast, very reliable, that’s called yeast. And so, in 150 years, bakers switched completely.

TWILLEY: Like I said, commercial baker’s yeast is just one microbe, not a community. Which has both pros and cons.

DUNN: So, commercial yeast is super boring, right. So nobody ever thought Saccharomyces cerevisiae, this baker’s yeast, was the most flavorful, that it had the best effect on the bread. We just thought you could make a ton of bread really quickly.

GRABER: Because not only is it a single yeast that you can buy whenever you need some, and that doesn’t need feeding or watering or loving care, but it also makes your dough rise a lot faster than that sourdough starter you’ve been keeping alive. By the 1960s, boring commercial baker’s yeast was available as shelf-stable granules in little packets. And, by then, bakers had also invented industrial processes that sped up the whole rising and baking process to just over three hours.

TWILLEY: This  bread—the bread of 1960s, the bread of our parents—this was not good bread. Karl says the 1960s was bread’s nadir. Sourdough all but disappeared.

GRABER: The 1960s sucked for bread, commercially. But it was also the time of good bread’s rebirth. The country’s first Zen Buddhist monastery was created in California in the late 60s. It was called Tassajara. The monks there baked bread slowly as part of their spirituality. They saw bread as being alive.

TWILLEY: And a young Zen student named Edward Espe Brown, who lived and worked at Tassajara—he published a book collecting the monks’ recipes in 1970. It was super homemade and hippie—the cover is made of brown paper, it was published in a tiny edition by Shambhala Press, and Edward received the princely sum of $100. But it sold out immediately, and went into second and third and fourth printings. Making your own sourdough bread at home became part of the counterculture—and a way to eat healthier.

GRABER: At the same time, there was another group of people who thought that commercial bread kind of tasted like crap. They weren’t inspired by spirituality or health, but by flavor. Between them, these two groups helped create the sourdough revolution.

TWILLEY: This revolution took a while to spread. During Karl’s own training as a baker, he never set eyes on a sourdough. It wasn’t till he started working at Puratos, in 1994, that he first encountered it.

DE SMEDT: I’d been to one of the better bakery schools in Belgium and we never learned how to make sourdough. It’s just not part of the educational program. So it was a discovery. I had to take out a bucket of the fridge. It looked strange. It smelled strange. It was funny when you touched it—it was a bit sticky.

GRABER: But Karl is thrilled to say things have been changing for sourdough.

DE SMEDT: And we see now, the latest 20—25 years there is a revival of sourdough and we think we are at the beginning of something very nice that will come in the coming years where sourdough will again take its place in the bakeries that it deserves.

TWILLEY: With that sourdough revival came a renewed appreciation for the diversity of microbes in sourdough starters—and they are diverse. As we discovered.

DE SMEDT: Come closer, come closer, because something very special is going to happen. You have to realize that what we have here is probably the most unique place in the bakery world.

GRABER: Karl led the group up the stairs and to a closed door.

DE SMEDT: Ready? Keep your eyes on the door, let’s go for some magic. Three, two, one…

BAKERS: Whoa! Ahhhh!

TWILLEY: And with that, we stepped inside the world’s one and only sourdough starter library.

GRABER: It’s a library, yes, but instead of bookshelves, there are 12 illuminated refrigerators with glass doors so you can see the jars inside. Karl’s collected 93 different sourdough starters from 17 different countries. And they look totally different from one another.

DE SMEDT: Some are liquid and some are stiff. And then some are very dark. Some are speckled. Some are almost looking like crumble, because they’re so dry. So there’s a lot of colors—dark to brownish to yellow, and then the normal white ones.

TWILLEY: Karl took some of the jars out and allowed us to smell the starters. Some smelled fruity, some were acidic, some were biscuity, some were creamy.

DE SMEDT: The Chinese, for example, one of them is very meaty. When I open the jar, it’s like almost a sausage, very savory. Some are really very pungent, when I open the jar and smell, you really feel the acids go into your nose, and it’s like if you were to have a spoon of very heavy mustard, the Dijon mustard—that reaction.

GRABER: Karl’s goal with this collection is to preserve the communities of microbes that make each sourdough unique. But for Karl, it’s also really fun.

TWILLEY: Karl is the keeper of the sourdough library. He can’t sell these starters or even give them away. Each unique microbial community still belongs to the baker who donated that starter in the first place. But Karl feeds them and takes care of them. And sometimes he plays with them, too.

DE SMEDT: I do take home some sourdoughs and I do some experiements and, yes, I do bake with them. And I discover some other things. Sometimes the fermentation power is totally different.

TWILLEY: When Karl is feeding the starters he puts them in small plastic buckets.

DE SMEDT: Some of them they just blow away the lid of these things. And other ones are just very, very slowly rising, fermenting. So there’s really differences in fermentation power, in flavor, in aroma, in the way the dough is feeling when you touch the dough, it’s different. So yeah.

GRABER: Karl’s point is that these starters are all different from one another. And the library itself is also unique. Nobody’s ever tried to conserve communities of useful food microbes for the future.

TWILLEY: Walking around the library, looking at these spotlit jars in their glass refrigerator vitrines, you really see each sourdough starter as a distinct, individual, precious thing. But how different are they microbially, really? Who’s living in those jars?

DUNN: Sourdough, in terms of the number of species we know how to grow, is toward the simple end. Often you’ll have two to four culturable bacteria species and one yeast species. It’s very likely, although we don’t know, that there are also things that are hard to culture in the lab that are in those sourdoughs, that make it a little bit more complex. But it’s toward the simpler end in terms of numbers of species. It’s not simple though in as much as different sourdoughs seem very different. And so if you were to look around the world, how many different species could you find in all of the sourdoughs? That’s actually a much longer list. And so an individual sourdough: simpler. This big picture of sourdough is far more complex.

GRABER: As Rob is explaining, a sourdough starter is an interesting creature, or, really, creatures. You can have a community of just a handful of different microbes that works perfectly together—as Rob says, maybe two to four species of bacteria, maybe one kind of yeast, and it’ll work. It’ll make sourdough.

TWILLEY: But what’s also probably true is that your sourdough starter could contain an entirely different community than mine, and they’d both still make sourdough. And it’s that diversity—that huge world of bacteria and fungi that can collaborate to raise bread—that’s what Karl is trying to collect.

GRABER: His library, as unique and impressive as it is, is probably just the tip of the iceberg. And maintaining this library is a lot of work—it’s not just collecting samples and putting them behind glass.

TWILLEY: Any baker can tell you what a commitment it is to keep a sourdough starter alive.

BARKER: I always describe it, if you have a sour culture, it’s like having a pet or a child, yeah?

GRABER: Paul Barker owns a bakery just outside London called Cinnamon Square. And he has many sourdough pets.

BARKER: You have to look after it. If you don’t feed it, keep it warm, or whatever. So unless you look after it, it will spoil, it will eventually die on you. So it’s a commitment to having a sour culture .

TWILLEY: In fact, there are even specialized sourdough hotels, where you can send your sourdough starter to be looked after if you’re going on a super long trip. A sourdough starter is really much higher maintenance than commercial yeast, so why do bakers use it? We asked Paul.

BARKER: Firstly, because the sourdough gives you a much different type of bread: different textures, more digestible bread, more nutritional breads. So I like the fact that you can get a totally different product. And you can be so creative with a sourdough, more so than a yeasted bread. So you can actually do a lot more with the shape in the baking, the decorations, I think—because you can get more from it whereas a yeasted bread, a commercially yeasted bread, you are just expanding your dough and baking it.

GRABER: Commercial yeast, as Paul explained—it makes the bread puff up, but that’s it. Paul knows that the microbes in his starter are giving him a different dough. It often has the right type of texture to allow him to play around more with the shape of his loaves. But what are those microbes actually doing to create these differences, and how are they doing it?

DUNN: So the microbes in the starter are starting to break down some of the hard-to-break-down things in the grain that you’ve given them to eat. And they are beginning to produce these gases that we think of as some of the really important flavors in the bread. But, as they metabolize the grains, they’re also also altering the structure of the carbohydrates that are present, which then is going to alter the nutrition of the carbohydrates, it’s going to alter the outside of the bread.

TWILLEY: As Paul has noticed and as Rob just explained, microbes improve the texture and the nutrition and even the look of the final loaf. They can even produce extra vitamins. But they also shape its final flavor—you can literally taste the difference between bread from different starter communities.

DUNN: And so butteriness—a lot of butteriness comes from which microbes are in your starter. The kind of sourness you have—how lactic it is versus how acetic it is—that comes from which microbes are in the starter.

TWILLEY: Rob told us that some sourdough bread has a particular gooey, melt-in-your-mouth feel that comes from a chemical called dextran, which is produced by a bacteria called Weissella. Weissella lives in some sourdough starters, but not in others.

GRABER: So: microbes are munching away on the flour, excreting things like buttery flavored lactic acid and yeasty farts that puff up bread. That much we know. But Rob and his fellow microbiologists don’t understand how all this microbial munching and excreting creates the differences between different finished loaves of sourdough.

DUNN: And the further you get down that chain of events, the less we understand about the mechanics of how all of that is happening. But what we do know is that all of the things that could influence those final flavors, final texture, final nutrition are things that we think of as predominantly microbial.

TWILLEY: So we don’t know. We really don’t know how the microbes are working their magic. We don’t even where they come from in the first place. But Rob wants to know. And so did we. And hence this giant 3-day experiment in Belgium. Which we have the exclusive first results from after the break.

(MIDROLL)

TWILLEY: Back to Belgium. Where we are about to conduct an epic baking experiment in order to figure where the microbes that are in a sourdough starter actually come from in the first place.

DUNN: So, in order to make a starter, you take a simple set of ingredients and you expose them to open air and to your body and to your home, and it starts to grow. It’s like making a garden without ever planting the actual seeds. The mystery to me is: what determines which life forms are growing in that garden? And so that’s the fundamental mystery: why is your garden different from my garden when we use the same things to start with?

GRABER: Many bakers think they know the answer to this mystery.

VILCHIS: I think is flour. But the hands of the bakery is very important too to the results.

BAKER: I think it’s probably a combination of all of the variables.

MARCUS MARIATHAS: It’s mostly, in my opinion, the reaction within the flour and water. That’s where it starts.

BARKER: I would assume the environment is going to play a part in it as well. Because it’s going to be a lot of cross contamination in bakery from different flours anyway and you can end up with different types of sours.

MADDEN: I feel like every baker we talk to has a different assertion about where the microorganisms from that sourdough starter came from. Some people are very clear: it’s likely coming from the flour. If I use a different flour, I’ll have a different sourdough starter and a different sourdough starter must be different microorganisms. Some people have suggested that it’s the water. That’s why San Francisco sourdough is San Francisco sourdough and you can never make it in New York. There are claims about it being in the wood of buildings.

DUNN: What I like about this project is that as scientists we have not had to come up with our hypotheses because the community of sourdough makers has provided us with the longest possible list of what they might be.

TWILLEY: From that long list there are four main hypotheses: that the microbes that make each sourdough starter unique and individual come from (a) the wheat, (b) the water, (c) the environment, and (d) the baker themselves.

GRABER: Rob says we know that there are different microbes on different grains. Even within the same grain, there are different microbes on different strains of wheat—different heritage varieties, for example. Or wheat that is grown in different ways, like organic wheat. And then, even on the same plant, you can find different microbes in the germ of the grain versus the endosperm. The endosperm is what millers use to make white flour. So this means that whole wheat flour has different microbes than white flour does. Rob says these all these variables in the flour itself could certainly be influencing the sourdough starters.

TWILLEY: Then there’s the hypothesis (b), the water.

DUNN: Water can conceivably kill things in the starter. It’s unlikely to be adding things to the starter because we have a pretty good list of what lives in water. I think people are surprised often that all water they ever drink, even bottled water, has microbes in it, but they’re not the kinds of microbes we characteristically see in sourdough.

TWILLEY: In other words, Rob is saying that the water might prune particular microbes out of a sourdough starter garden, but it’s unlikely to be contributing any new microbes itself.

DUNN: The other thing though that that can then contribute to the starter is what falls from the air into the starter.

GRABER: This is hypothesis (c), the environment around you as you make the starter. Rob says that plants might have a particularly strong impact, because of the insects they attract and the microbes on those insects.

TWILLEY: And then there’s just the bacteria that are swirling around in the dust and air. Some of those come from pets, if you have pets. The majority of them, usually, come from your own skin and the skin of the people you live with.

GRABER: And finally, hypothesis (d), the baker.

TWILLEY: Specifically, the microbes living on the baker’s skin.

DUNN: We can think of many ways that microbes differ from one person to another person.

TWILLEY: For example, there’s that gene that determines whether you have sticky or dry earwax.

DUNN: And depending on which version of that gene you have, your skin microbes in your armpits, but also around your body more generally, are super different.

GRABER: There are also microbes on your skin that don’t live on your skin. They get there when you touch parts of your body that have other microbial communities. Like your gut microbes.

DUNN: And then we know that human women and human men differ greatly in microbes because of vaginal microbes. And so women have way more Lactobacillus in general, but especially in vaginal communities, and those sort of travel around through the day-to-day business of being a human.

TWILLEY: These vaginal microbes are particularly interesting because Lactobacillus is a key part of most sourdough starter communities.

DUNN: Yes. So, in some cultures, sourdough is mostly or exclusively something that women bake. And to me it’s really intriguing to think about does that have something to do about the unique sourdough community that emerges when women make sourdough versus when men make sourdough.

GRABER: This three-day Belgium adventure, the experiment we’re watching unfold—it’s designed to try to tease out where the microbes in the sourdough come from. A, B, C, or D.

TWILLEY: To be precise, it’s designed to isolate two variables from these four possible sources for the microbes in sourdough—the microbes on the different baker’s hands and in their environment. Those are the variables.

MADDEN: They were shipped the ingredients, they were given the same protocol, the same recipe.

GRABER: That is, these bakers were shipped exactly the same flour. Not the water, because based on the existing research, Anne and Rob don’t think the microbes in water plays a big role.

TWILLEY: Anne and Rob cultured the microbes out of that flour, so they already have a list of the microbes that are being contributed to the starter from the wheat.

GRABER: Like Anne said, the bakers were given very specific instructions about exactly how much flour and water to use and exactly how long to ferment their starters. The goal is to make this all as controlled as possible.

TWILLEY: So all these bakers, men and women, in different parts of the world, they all made their sourdough starter using the same flour according the same protocol. And then they put their starters in a baggie and they brought it with them to Belgium

MADDEN: And that was a really fun part, when we got to open them all up and they’re coming in and some of them smell like vinegar and some of them smell more like yogurt and some of them smell creamy.

GRABER: As soon as the bakers arrived, Anne and Rob opened packages of sterile swabs, like super long Q-tips, to get samples of those rich microbial communities in the starters.

MADDEN: Just one double swab per.

GRABER: Then we took a break from the science. We all introduced ourselves and met each other, and everyone talked bread.

TWILLEY: The final part of the experiment that day was refreshing the starters, according to the protocol.

BAKER: I’m going to put my starter in this bowl, first of all dilute it with the water, and then add the flour on top, mix it, put it back in here, and then we’ll wait until tomorrow.

GRABER: And that’s it?

BAKER: And that’s it.

TWILLEY: And then we all ate dinner together accompanied by lots of bread, and day 1 of the experiment was over.

GRABER: First up day 2? After breakfast featuring lots of bread, we got to everyone’s not-so-favorite part—getting swabbed to find out what microbes live on their skin.

TWILLEY: Paul from London was up first.

MADDEN: Now, I’m going to be swabbing your hands, and I’m going to ask that put your hands out just in a way that I can apply some pressure. And I’m going to spend a few seconds.

BARKER: Yeah.

MADDEN: Just going over the front and then I’m going to ask you to flip and then I’ll do the back. And if we could not talk over the swab when it’s out so that we can not introduce some of our oral microbes.

BARKER: Sure.

MADDEN: Thank you.

TWILLEY: Anne was swabbing the baker’s hands because if any microbes are going from a baker’s body into their sourdough starter, they are probably getting in there via their hands.

DUNN: You know it will be wonderful in some future version to you know top-to-bottom swab all these bakers and really start to tease out, you know, which body part is really contributing. But we had to start somewhere and so we started with the hand connection.

GRABER: In case you’re getting a little grossed out, don’t worry. The bakers do wash their hands. And they should wash their hands. Anne made sure to emphasize that. Even after you wash your hands though, there are still microbes on them. They’re everywhere.

TWILLEY: So, next step: after their hands were swabbed, the bakers were allowed back into the test kitchen to be reunited with their starters. Which they could hardly wait. It was like parents at the kindergarten gate. But before they could be fully reunited, the starters all had to be tested with some cool science gear, to find out their pH and their organic acid content.

TWILLEY: Once again, the sourdough starters all looked—and smelled—completely different.

KASPER HANSEN: My sourdough is called Danish Dynamite.

GRABER: That’s right, Danish Dynamite.

CASPER: So a lot of activity inside. So, as you can see, up side of the glass here.

TWILLEY: It was like looking at baby photos, I’m not kidding. Everyone thought theirs was the prettiest of all.

GRABER: You’re smelling your sourdough?

TOMMASO RIZZO: Smell is buttermilk—smell, taste, aroma.

GRABER: Can I smell? Mmm, yeah, it’s got a little sweet. The bakers made their bread and left it to proof overnight. And, as that official science-experiment bread was rising, the bakers were set free in the test kitchen to let their pent-up creativity run wild.

TWILLEY: And they went to town. Hakan made this crazy Turkish bread that had lots of melted cheese and a cracked egg on it. Leticia, the Mexican baker, she was putting cocoa and raisins into a sourdough loaf. Someone made pita bread.

GRABER: I’m going to taste some of this. Mmm. Nicky, hot pita with garlic butter? It’s really good.

TWILLEY: It’s really good. That’s good. So look, let me do this.

GRABER: Mmm, the smell.

TWILLEY: I’m squeezing the bread like it’s a bellows on an accordion or something. Or trying to light a fire. This is what I’m doing.

GRABER: That smells amazing. It’s like as you squeeze the dough the scents in the air pockets just, like, get blown right at your face.

TWILLEY: So I stood here. Stavros, like, pumped the bread in my nose, and Vassilis was like “This is sourdough.” We sniffed bread and we ate bread, and then we ate more bread.

GRABER: And then we ate dinner. Which also had some bread.

TWILLEY: And then we rose bright and early on the third day, had some bread for breakfast, and went back into the kitchen to bake the science-experiment bread. But… there was some tension.

GRABER: Tommaso, for one—he’s from Italy—he didn’t want to put his bread in the oven when everyone was told it was oven time. He said the dough wasn’t ready for baking—it hadn’t risen enough. Rob whispered to us that he and Anne were having a hard time making sure that all the bakers kept to the scientific protocol.

DUNN: Yeah. So we’re thinking about it right now. There’s a tension between what people view as counting as a bread. And, uh, what we want.

TWILLEY: Tommaso was overruled. In the nicest possible way. And all the bakers’ dough went in the oven at the same time. And the same way that their starters had looked and smelled really different, despite having been made from the same flour using the same instructions, the dough looked really different as it went into the oven, too.

GRABER: You could see some really big air bubbles in some and none in others. Some rose a third of the way up to the tops of the baskets, some rose all the way to the top. Some were super bubbly on top, some were shiny and smooth. And then the bread came out of the oven.

GRABER: Oh. Those are pretty. (OVEN DOOR CLOSING)

TWILLEY: Some of the bakers were happy and some were not. So these are Tom’s, you like the look of them?

WALTER: I like them. Because when it’s cracking open, you see black line. And Karl calls it eyeliner—so we have to bake it so—eyeliner on the bread.

TWILLEY: And eyeliner is a good thing, right?

WALTER: Yeah, yeah.

GRABER: I learned something new—I never knew bread should have eyeliner on it. It’s basically the nice, dark, cracked edge you see at the top of the loaf. Tom’s loaf had really lovely eyeliner.

TWILLEY: This has a lot of nice fish eyes or blisters.

GRABER: Little bubbly blisters on the cooked crust are another sign of a great sourdough. But some loaves didn’t look as good. Like Paul’s. And this one doesn’t look like it did very much over here, it didn’t even crack.

TWILLEY: Which are yours?

BARKER: The ones that are looking very sad at the back. The two behind this one here.

GRABER: No, they’re not very…

BARKER: Yeah.

TWILLEY: And then, as soon as it was cool enough, all of the loaves were sliced in giant bread-slicing machines. And the bakers were asked to evaluate a slice from each loaf. They had to assess its appearance, its smell, and, of course, the way it tasted.

TOM REES: So we’ve got kind of two different colors, I see already. One which is a bit grayer, and one which is a bit more yellowy, creamy color.

TWILLEY: And is that reflected in differences of smell too?

REES: Yeah, so the greyer ones—the greyer ones have less of an acidic aroma

BARKER: Some are creamy and some have gone kind of more reddy, kind of browny, sort of hints. So there was a distinct difference in the color, which is quite interesting. I wouldn’t have expected that considering we are all using the same flour, the same ratios of ingredients.

BAKER: Like the one of Guillermo is dense and stronger, and from Tom, it’s very fragile and very open. But the taste and smell is about the same.

VILCHIS: For example, Hakan is very very similar to Kasper. I think is the same bread. Incredible. Paul is the same than Guillermo.

HANSEN: It’s much more like wheat—not so fruity. Hakan and Tom, taste more—have more acid taste.

DUNN: And so in this case we know that all those differences from bread to bread are really microbial.

GRABER: But it might not actually be because the starter contained different microbes. The exact same microbes can create different smells and tastes just based on the temperature that they grow in, for instance. So these results, that the breads smell and taste different? Could just be because the temperature in London is different from Guadalajara.

TWILLEY: Sensory evaluation was not enough to answer this question. Instead, Rob and Anne had to take to their swab samples back to the lab and analye them.

GRABER: A few months later, we called Rob up to find out how it all went. (PHONE RINGING) Hey Rob! So Belgium ended. You packed up to go home. How did you feel?

DUNN: I felt super full.

GRABER: I felt really full, too, just so you know.

TWILLEY: I was never going to eat bread again. And then I did.

DUNN: No, I’m ready for more bread to be honest. There’s been time.

TWILLEY: Science takes time, but this science took a little bit longer than Rob wanted because his samples—the swabs from the bakers’ hands and the sourdoughs starters—they got held hostage in Belgium. Trying to get these kinds of biological materials across borders can be tricky. Rob is a patient man, but even he was getting a little frustrated.

DUNN: And then, amazingly, just last week, we got the first results from that decoding of DNA.

GRABER: Rob, Anne, and their whole team spent a day just marveling at the data and poking around. They were trying to figure out if they could make any sense of the data just by looking at it. Which, of course, they couldn’t.

DUNN: But then eventually we started to formally analyze what’s going on with the patterns of the data and that’s where it starts to get interesting. And so the first one of those analyses happened on Friday and the second one happened about two hours ago.

TWILLEY: So tell us! What did you find?

DUNN: Well, the first thing last week was a result we weren’t looking for, we didn’t anticipate. And I had no idea it was even possible.

GRABER: It’s about the bakers’ hands. Normal hands usually have Staphylococcus, and some armpit microbes, some bacteria that are the same as acne bacteria, maybe some random bacteria from things you’ve touched recently.

DUNN: When we looked at the bakers’ hands, their skin bacteria on their hands was about half sourdough bacteria. And so they, like, have sourdough paws.

TWILLEY: Sourdough paws!

DUNN: We’ve looked at zillions of hands. We’ve never seen anything like this. And so the first result is that the bakers themselves have changed in response to their occupation.

TWILLEY: Normal hands like mine and Cynthia’s and Rob’s—they are something like 2 to 4 percent Lactobacillus.

DUNN: On the hands of the bakers, it is like it’s the star of the show. It’s wild. I mean, if it’s right, you should be able to put flour and water on a baker’s hand and it should start to ferment immediately and become acidic.

GRABER: Working with sourdough has entirely changed the microbial environment on the bakers’ skin. They’ve been colonized by their pets! Rob wonders if the bakers spend so much time with their hands in acidic dough that the sourdough Lactobacillus microbes end up with a competitive advantage over normal skin microbes.

TWILLEY: So that is weird. But it’s not what Rob and Anne set out to find. What they were trying to understand from this 3-day Belgian breadfest is whether the microbes in the sourdough starter come from bakers’ hands—not whether bakers’ hands are somehow different from normal hands.

DUNN: So what we saw two hours’ ago was that there’s a group of bakers that has very different sourdoughs, and the unusual microbes in those sourdoughs are also on their hands.

GRABER: One question answered. The bakers who have weird bacteria on their hand have the same weird bacteria in their sourdough. There is a connection. Individual bakers do indeed seem to influence their starters. But so, does this difference influence the flavor of the resulting bread? Rob doesn’t know, he hasn’t done that research yet, but he has a hunch.

DUNN: I predict that second group has more unusual flavors. And we should be able to capture that. We’ll see.

TWILLEY: Stay tuned. Meanwhile, what Rob and Anne have done is sit down and compare the list of microbes that were in the flour and the list of microbes that were on the hands and the list of microbes that were in the starters.

DUNN: We get a total of about 193 kinds of bacteria in the sourdoughs. which is a lot more than the bakers tend to think is there, which is interesting in and of itself. Something like 80 of those are also found on hands. And roughly the same number seems to be found in the flour. And there’s overlap between the flour and the hands. We saw almost nothing in the water, so they’re probably not coming from the water.

TWILLEY: But they did see some microbes that weren’t accounted for, that were not from the hands or the flour. They were maybe microbes that were just floating around in an individual baker’s kitchen.

DUNN: Yeah, they could come from a leaf outside the bakery. It could come from a bowl or a spoon. But it’s not so surprising that we haven’t found where all those microbes are coming from—and, in some ways, that leaves the bakers some magic. Where does the stuff we’ve not measured yet coming from? Just magic. You guys can keep that.

GRABER: Rob also told us another new finding that totally contradicts what he told us back in Belgium, earlier this episode. Remember how he said that sourdough starters have three or four species of bacteria and maybe one species of yeast? Rob says based on these new samples he’s seeing ten species of bacteria in the average sourdough starter and maybe three species of yeast.

DUNN: We now have enough data to say that I was wrong when I was describing the simplicity of the starters. Which also means the whole literature is wrong.

TWILLEY: Folks, this is science in action. We think we know things, like about how many species of microbes live in a sourdough starter, and then we do some research and discover we don’t. But Rob pointed out that sourdough starters are still not particularly complex in microbe terms.

DUNN: And so part of the story that’s super fascinating to me is, you put out flour and water, all around the world, and somehow you can create a very similar ecosystem out of what for bacteria and fungi is a relatively small number of species. If you put out sterile soil in this many sites globally, you’d be looking at 20,000 species. And so, on the one hand, the individual starters are more diverse than we tend to think. On the other hand, that global picture is actually a lot simpler. So that was really interesting.

GRABER: Rob and Anne and their collaborators have really only just begun analyzing this data. Over the next six months, they’re going to be figuring out what types of compounds each species of bacteria can produce—not necessarily that they’re actually making those compounds in the starters, but that they can.

TWILLEY: And then they’re going to match those compounds to their possible effects in bread—different flavors, different textures, different nutritional values.

DUNN: The other part is we’ve barely touched the fungal data. And so that will mean we’ll be spending a fair amount of time on that even this coming week.

TWILLEY: So there’s much still to be done with just the data from our Great Belgian Bake Off. But there’s also just more sourdough research to be done in general. Our Belgian breadfest was only one of the sourdough experiments Rob and Anne have got going on the lab right now.

GRABER: They’ve already gotten about a thousand people from around the world to send in their sourdough starters. Rob and Anne want to get a big picture of sourdough diversity. They’re hoping to see patterns, like whether some species are more common in some areas of the world. And they’re already starting to see some results.

TWILLEY: Rob told us that, in terms of bacteria, there seems to be a shared sort of pool that colonizes grain and water mixtures all around the globe. In other words, the same bacteria are pretty much everywhere and then which end up in which starter seems to depend mostly on the flour and the baker, as we just learned.

GRABER: But they are seeing a little bit of geographic variation with bacteria. Some bacteria tend to live in more northerly Scandinvanian countries, for instance. That’s not the only anomaly.

DUNN: There’s a little bit of a hint so far that maybe France is kind of special.

GRABER: France is special.

DUNN: But the fungi we’re seeing globally have a lot of geography. And so there’s one one kind of yeast—a kind of fungus—that we’ve basically only seen in Australian starters. We know that the yeast can do a lot in terms of flavors and aromas. If that unusual yeast is playing a big role, then there could be a flavor that you could only actually savor when you’re in Australia. And we don’t know that yet. That’s a fun idea.

TWILLEY: Sourdough tourism is going to become a thing, just wait and see.

GRABER: One of the things Rob and Anne are going to do over the next year is bake some bread from these thousand starters that they received. That way they can start to assess flavor while controlling for the other ingredients. The ultimate goal is to arrive at microbial recipes for sourdough deliciousness.

DUNN: Once we do that, that will be the hope—that there is some mix that really gives you the perfect butteriness or the sourest souriness. Is souriness a word? I don’t know.

GRABER: Rob and Anne are also working with colleagues to tease out the evolutionary history of sourdough. They’re going to be working out how microbes in starters change over time. So, eventually, they’ll be able to tell you, if you’re using your great-grandma’s starter, are those your great-grandma’s microbes? Or, as listener Danae asked, if she gives her sourdough starter to a friend, will it change—and if does, how quickly?

TWILLEY: So there’s still tons to figure out about sourdough, but Rob is on it. And we’ll keep you posted as his results come in. It’s super exciting research. Not just because we love microbes.

GRABER: A round of applause if you haven’t keeled over yet from taking a shot every time we say microbes!

TWILLEY: We do love microbes, But we also love this research because it points the way to a future of even more delicious bread!

MADDEN: And so I think the question is the next step, which is: What microorganisms create what flavors and aromas and traits in bread that we want. And then we can start tracking down what microorganisms might be leading to those traits. And so you can imagine a future where you could think about the kind of bread you want. Maybe I want it to be crusty and kind of chewy with fruity notes. And by having that choice of bread, there’ll be a list of species that will work together to create that. So you’ll have a designer sourdough.

(MUSIC)

TWILLEY: Thanks this episode to the Burroughs Wellcome Fund for supporting our reporting on biomedical research.

GRABER: Thanks also to some of our Supreme Fan level Patreon supporters: Andy Allen, Lori Schultz, Justin So, Robert Wells, Alex Sol Watts, Eric Schmidt, Corinne Lewis, David Kohn, Matt Rooney. We cannot thank you enough for your generosity in helping keep Gastropod going.

TWILLEY: And a big thank you to Puratos, who hosted this experiment but also hosted Cynthia and me in Belgium. We have photos and links to Karl’s magical Sourdough Library on our website, gastropod.com

GRABER: Thanks so much to Rob Dunn and Anne Madden for letting us follow them around for three days and try not to get in the way of all their swabs.

TWILLEY: And thanks also to the lovely bakers, who couldn’t have been more of a fun group to hang out with while doing some cutting-edge science. And some competitive-level eating.

GRABER: We are going on a brief break over the holidays. But we’ll back in 2018. We have an amazing season lined up for you. If you’re on our sustaining supporters list, you’ll get a sneak peak at what’s coming up. Thanks to all of you who listen, who support the show, who write in, who take part in our Shareathon—we do this for you, and we couldn’t do it without you!
crumbs to try to identify their microbes. Could those microbes be the same as the ones in sourdough today?

This is a transcript of the Gastropod episode Cannibalism: From Calories to Kuru, first released on October 24, 2017. It is provided as a courtesy and may contain errors.

(CLIP FROM THE SILENCE OF THE LAMBS)

TWILLEY: So if you know this famous clip from “The Silence of the Lambs,” you will know that this episode, we could be discussing one of three things. Chianti. Fava beans. Or…

GRABER: Oh how I wish we were discussing chianti or fava beans. But no, this episode, we’re all about cannibalism. Happy Halloween!

TWILLEY: But, honestly, although we began with Hannibal Lecter, this episode is really not a gore-fest. This is, after all, Gastropod, where we look at the science and history of food. And the science and history of cannibalism turns out to be fascinating. I’m Nicola Twilley, by the way, the one who is not in danger of fainting this episode.

GRABER: And I’m Cynthia Graber, the one who has never seen “The Silence of the Lambs” because I am far too squeamish. But there’s interesting stuff here. We’ve all seen those nature documentaries where the spider consumes its mate after sex, but really, how common is cannibalism in the animal world? And why does it happen?

TWILLEY: And how common is it among humans, in the past and still today? All that, plus a caloric breakdown of the human body, for those of you who want to turn cannibal but are watching your weight.

(PRE-ROLL)

(MUSIC)

GRABER: There’s one thing I wondered when we first decided to do this episode, and it’s the question I just asked. Really, how common is cannibalism in other species? It’s such a taboo among humans. Is there a biological reason eating each other would be disgusting for other animals, too?

TWILLEY: To find out, we called up Bill Schutt, who is the author of a new book called Cannibalism: A Perfectly Natural History.

BILL SCHUTT: Well, it’s really common. And that was a surprise to me. I’m a zoologist but I was not a cannibalism expert.

TWILLEY: Bill told us that up till quite recently, most zoologists, including him, thought that cannibalism was pretty rare, in all species.

SCHUTT: Except for a couple of strange creatures like praying mantises and black widow spiders, the party line was basically that if you saw cannibalism in nature it was because of a lack of nutrition or cramped captive conditions. If you took a bunch of animals and stuck them in a small tank or a cage then all bets were off, they would cannibalize each other. But over the last thirty years or so, scientists began to find out individually and then they—somebody finally put this together—that cannibalism takes place for tons of reasons that are quite natural and have nothing to do with with running out of food.

GRABER: So it’s common, or at least more common than scientists thought, but there are some really good biological reasons why you might not want to eat members of your own family.

SCHUTT: And one of them has to do with with something called inclusive fitness, which is pretty much a measure of how many genes you have in a population, and if you’re killing and consuming your own kin you are really decreasing your inclusive fitness. And the other is because there are species-specific parasites and diseases that can be transmitted.

TWILLEY: And yet, like Bill Schutt said, there’s a whole lot of cannibalism going on. Particularly at the squishier end of the spectrum.

SCHUTT: If you look across the entire animal kingdom, in the invertebrates, in insects and in spiders and in snails and things, cannibalism is quite common.

(DAVID ATTENBOROUGH CLIP)

GRABER: Spider sex. You know it. The male approaches the female cautiously—after all, he doesn’t want to get eaten BEFORE he manages to get the act done.

TWILLEY: And she’s usually twice his size, total dominatrix.

GRABER: In the Australian redback…

TWILLEY: Where the guy is only a fifth of the size…

GRABER: The female rewards the male for having done his duty by vomiting her stomach juices onto the tiny creature hanging onto her to start pre-digesting him. Yum.

TWILLEY: Amazingly, he still comes back for round two at this point, even as he is being liquified. Praying mantis males keep going even after the lady mantis has eaten their head. But why? I mean, sex is great, but not that great, surely?

GRABER: It might seem like there there’s nothing in it for these poor guys other than those few moments of bliss. But scientists have found a number of reasons why sex cannibalism makes sense. The redback spider ladies will resist come-ons from other males if they’ve cannibalized their first suitor. So that cannibalized male’s sperm is the one that wins.

TWILLEY: Plus, counterintuitively, cannibalized males seem to go at it for longer and thus deposit more sperm and thus father more baby spiders. I suppose there’s a kind of desperation born out of being coated in stomach juices.

GRABER: Sexual cannibalism has been reported in 16 out of 109 spider families. So not all spider sex is deadly, but it’s definitely going on. Okay, that’s enough sex cannibalism for the moment. Now onto why parents would eat their babies.

TWILLEY: In this particular niche form of cannibalism, fish are the undisputed leaders. According to Bill, ichthyologists consider the absence of cannibalism in a fish species to be the anomaly.

GRABER: Picture the open ocean. In order to make babies, the female releases a cloud of eggs, maybe millions, and the males release clouds of sperm. Only some make it to become baby fish, but there’s all those calories available in the water. Bill says the eggs look to fish just like a handful of raisins might to us. Why not eat them? So they do.

TWILLEY: And finally—keeping it in the family here—oftentimes the kids eat other, too. This is a strategy Bill’s seen a lot in birds.

SCHUTT: Cannibalism as a lifeboat strategy where you’ve got say, a couple of nestlings and they’re born asynchronously. So one is going to be larger than the other. And if there’s enough food to go around then fine but if not then the smaller nestling will sometimes get cannibalized.

GRABER: Survival of the fittest. It’s bird-eat-bird out there. Sometimes this juvenile cannibalism is just training for the real world.

SCHUTT: Then there are these sand tiger sharks, where the eggs hatch internally. And there are eggs of different ages. So the oldest on each side of the reproductive tract, once they use up their yolk, will start to eat the eggs and once the eggs are gone they’ll eat their brethren. Smaller and and quite nutritious. So when they’re born, there are only two of them. And in a sense they’ve been trained to be predators while still inside their mothers.

TWILLEY: Natural-born killers indeed.

GRABER: By the time you get to mammals, scientists have only found cannibalism in 75 out of 5700 species. It’s much more rare.

TWILLEY: But it happens, and for much the same reasons: survival, basically. When animals are hungry, sometimes they’ll scavenge off their dead relatives. So they’re not killing them for food, but you know, if they’re dead already, why not?

GRABER: Sometimes if animals are living in a crowded and stressful environment, they start to see their neighbors as food. And then there’s protecting your own genetic line. You want your babies to be the ones that live.

SCHUTT: So, for example, if you are a lion and you take over a pride and there are females who have cubs from other males, you kill and sometimes eat those young. And so you are really terminating the maternal investment in those young so that the females come into estrus quicker and then you can mate with them if you’re the male who took over.

TWILLEY: So bugs are eating bugs, fish are eating fish, some mammals are eating other mammals. But surely among our close relatives, this sort of behavior isn’t going on?

GRABER: It’s rare, but it does exist. Bill says that in primates, cannibalism has been seen only in 11 out of 418 species. Not a lot. It’s usually stress related, or it’s about aggression, like when males patrolling their community come across neighboring male patrols. Like other soldiers.

TWILLEY: OK, that’s primates. Who’s next? That’s right, brace yourself, Cynthia. It’s time to talk about human cannibalism.

GRABER: I’m working on it. Okay, turns out, there’s quite a bit of archaeological evidence of cannibalism among early humans.

JAMES COLE: So the oldest is Gran Dolina, which is a site in Spain. And it’s dated to about 936,000 years ago, to a species called Homo antecessor. And what we see there is a small group of people, so two adults, three adolescents, and six children, that seem to have been butchered and eaten by another group of Homo antecessor who were living in that region.

TWILLEY: Meet James Cole, he’s principal lecturer in archaeology at the University of Brighton in England. And he’s studied cannibalism in prehistoric times, when there were a bunch of different human species, not just Homo sapiens.

COLE: And certainly if you look at human evolution, well, difficult to say really if all human species conducted cannibalism but certainly a lot of them did. So it seems to have been a regular part of our behavioral development for many millions of years.

GRABER: It might seem to be common, but how do we know for sure? What kind of evidence can you find from almost a million years ago?

SCHUTT: If you really want to prove that cannibalism took place you’d need to find a coprolite, a fossilized fecal pellet, and then be able to show that there was for example human DNA or human hemoglobin or myoglobin inside that—those feces.

TWILLEY: And we haven’t found that. But without the smoking gun of a fossilized turd, how exactly is James so sure that our prehistoric fellow men were eating each other?

GRABER: Well, archaeologists have found human bones that clearly had been cut.

COLE: So there’s two potential explanations for why you might have a cut mark on a human body. The first is that yes, you are—you’re cutting it, you’re butchering that carcass to extract the flesh. Or the second explanation is that you are cleaning the carcass of flesh for some kind of ritual purpose.

TWILLEY: James says both kinds of cutting went on, if you look at the fossil record. Some cuts are the kind of cuts you’d make if you were stripping flesh from bone for burial—not for eating. And some cuts are the kind of cut you make if you’re butchering a body for food.

COLE: The key thing here is that the actual signatures, so the types of mark on the bone, are very distinctive. So if you’re butchering, you’re generally getting cut marks at points where you get things like cartilage. Whereas if you are cleaning the body for secondary burial, you get lots of scrape marks along the length of the bone. And what it looks like from the archaeological record is that most of the cut marks tend to fall around the locations where you would expect butchery marks to be.

GRABER: Bill agrees.

SCHUTT: So if you treat human bones the same way that you treat the game animals that lived in that area then that’s a strong indication that cannibalism took place.

GRABER: This was happening among all Homo species. Homo antecessor, Homo Neandertal, Homo erectus, for example.

COLE: And then our own species also seem to have engaged in this. So we have a sparse fossil record and within that sparse fossil record we are still picking up signatures of cut marks on hominin bones. So what that potentially means is that it probably was a frequent behavior because we’re picking up the signature of this act in a very small record to begin with.

GRABER: So we know it was happening. And we know it wasn’t super rare. But then why was it happening?

COLE: Okay, so when I was looking at the nutritional value of the human body, what I wanted to try and understand or establish was whether the act of cannibalism was actually nutritional in in nature.

TWILLEY: Obviously, James and his archaeologist colleagues mostly look at bones. And bones can tell stories, for sure. They can tell us that humans likely ate other humans. But they can’t necessarily tell us why those humans did what they did.

COLE: So what that means is that when these acts are looked at from the archaeological record, they’re generally boiled down to two very broad interpretations. On one hand it’s nutritional, or it’s ritual.

GRABER: Until recently, most archaeologists believed that cannibalism among our prehistoric ancestors was for nutritional reasons—they were hungry, there wasn’t much food, so other humans ended up seeming pretty tasty. And archaeologists thought that ritualized cannibalism—like for religious purposes or burial or war—that only started about 15,000 years ago among Homo sapiens.

COLE: And I wanted to know, okay, if we’re calling these acts nutritional, how nutritional are they compared to other animals that we knew were eaten by these hominins in the same time? So that’s why I wanted to look at the calorie values of a human being and then compare them to that of something like a mammoth or an auroch or other Ice Age fauna.

TWILLEY: This is really a very reasonable sort of thing to want to know. Are humans good food compared to a mammoth? But then when you start to think about it, how exactly do you go about figuring that out?

COLE: Yeah, so thankfully I didn’t actually do any sort of uh—I didn’t have to do any practical elements for the study.

GRABER: What James did manage to do was find four studies from the 1950s. The researchers had dissected four males. And the point of that research was to understand the chemical composition of the human body.

COLE: So what those studies did is that they broke down the values of the human body into protein and fat values amongst others. But what’s interesting for calories is that if you know your protein value and you know your fat value and you know the weights then you can actually convert those into calories. And fortunately in those 1950s studies, they had also recorded the weights of all the body parts that they were examining and they gave the protein and fat values of them.

GRABER: James just had to do some basic math.

TWILLEY: So break it down for me. If I ate one raw male, how long would I have to spend on the treadmill?

COLE: Okay, so kind of the average weight that came through from those four studies was 65.9 kgs and that returned a full body value—so that includes all of the organs and the guts and you know things that you would never even think about eating—but that returned kind of a value of about 143,770 calories.

GRABER: James has an amazing table that lists the calorie count organ-by-organ.

TWILLEY: Skin is surprisingly high in calories, folks. OK, so now James knows the caloric value of a human. A human male that is. No one has established the precise chemical composition of woman, so we don’t know how many calories we’d bring to the table. James suspects a little more thanks to our higher body fat percentage.

GRABER: Just another way women are underrepresented in science.

TWILLEY: James’s next step was to compare humans to the animals we know our prehistoric forebears ate.

COLE: A mammoth for example comes out almost, you know, three million, six hundred calories and a woolly rhino at one million, two hundred and sixty.

GRABER: James says that a horse would be about 200,000 calories, and a boar is about 324,000 calories. A lot more than a dude.

TWILLEY: Like really a lot.

COLE: And for me, you know, you get a much higher calorie return by going after a single horse or a single deer than you do by going after a single person or a group of people. And so that makes me think that maybe there’s something else going on here that’s not just about calories.

GRABER: Hunting is in fact hard work, but killing another human for food isn’t necessarily so easy either. We fight back. We have family members who might avenge our death. A human male is not a free lunch.

COLE: So I kind of concluded that it’s likely that there are social motivations behind these acts all the way back into antiquity, you know almost a million years ago. And it’s not just about survival cannibalism or the fact that you know you don’t have any other food to eat, although they’re almost certainly also happened.

TWILLEY: In other words, James says, you shouldn’t think of early humans as just these brutal desperate creatures. Even though the cut marks on some bones show that humans were eating each other as food, James is saying that at least some of the time, that wasn’t out of hunger. Instead, ancient humans were likely eating each other for much more sophisticated reasons, to do with spiritual beliefs about life and death.

COLE: So these are a culturally complex and culturally diverse species. Just in the same way that modern humans are culturally diverse and complex where we have different practices around death and burial throughout the world.

GRABER: That said, like James pointed out, our early ancestors and their hominid cousins were also probably eating each other when there was no other option around. And we know that still happens today.

SCHUTT: Well when you are in that type of a condition, where there’s no food and you are starving. You’ve eaten your pets, you’ve eaten the shoe leather, you’re eating hides. This is the Donner Party.

TWILLEY: The Donner Party is one of the most famous cases of survival cannibalism in recent history. It took place in the 1840s and it’s a gruesome, gruesome story, but the short version is a group of westward bound settlers left it too late to cross the mountains into California before the winter hit. So they got snowed in. Lots of them died. And the survivors ate them. One guy, Louis Keseberg—when he got rescued he had eaten nothing but humans for two months.

SCHUTT: When you get to that point then all bets are off. If you’re presented with the fact that there are dead around then you are either going to consume them and probably try to feed them to your children or your relatives or you’re going to die. And that is a choice that is made in those incredibly difficult circumstances, whether your city is besieged or whether there’s a horrible famine or you’re stuck in the Andes like the Uruguayan rugby players.

TWILLEY: Bill’s referring to the famous plane crash in 1972, where the survivors also ended up eating their fellow dead passengers, in order to survive.

GRABER: There are other famous examples of this happening on a much more massive scale. In Russia, during World War II, Leningrad was under siege for almost a full three years. Thousands of people ended up eating other people to outlast the siege. Lots of those survivors were later prosecuted for cannibalism.

TWILLEY: Or take the largest famine in recorded history, in China. It began in 1958, after Chairman Mao launched his disastrous Great Leap Forward—an agricultural modernization plan based on complete BS. The harvest failed repeatedly, 30 million people died of starvation, and cannibalism became widespread.

GRABER: This wasn’t the first time starvation cannibalism was documented in China. One researcher found 177 incidents of it, dating back more than 2,500 years. In the oldest example, families apparently started exchanging children so they wouldn’t have to consume their own relatives. Amazingly, the emperor actually made that practice legal in 205 BCE.

SCHUTT: The thing with China is, you know, it makes it sound like China is—that this always happens in China. Well, the thing is, that’s not necessarily the case but they took such amazing records. Their historical records are really unsurpassed. So they documented everything. So we now get to read about these examples of famines and the practices that they undertook in order to survive.

TWILLEY: But it wasn’t all survival cannibalism in China. After the break, we get into the peculiar practice of medical cannibalism. Which turns out of have been popular in the West, as well. In fact, it still goes on today.

(MID-ROLL)

TWILLEY: So here’s my question. If—as the archaeological evidence seems to show—cannibalism happened on a relatively regular basis among our prehistoric ancestors, when did it become such a horrifying taboo?

GRABER: Bill traces it back to the ancient Greeks. In the Odyssey, the evil giants eat people. The Greek gods became cannibalistic when they were upset. And then Bill says in Judaism and Christianity and in Islam, burial practices became super important and eating people was absolutely vilified. And, think about it: the body is basically the spirit made flesh in these religions. Jews can’t even be cremated because the body has to be intact for when the messiah comes.

TWILLEY: Christians eat the body of Christ and drink his blood as part of communion. If you’re Catholic, you are supposed to literally believe that the wafer is his body and the wine is his blood.

GRABER: This sounds like a pretty major contradiction, right? Eating a human body is absolutely taboo in Christianity. And yet for Catholics, transubstantiation is meant to be literal. But it just shows how powerful the idea is, that consuming his flesh and blood creates a kind of union with Jesus.

TWILLEY: In fact, it’s precisely because it’s so powerful that eating people just casually for a weeknight dinner—or even as part of a very solemn ritual that was outside the Christian church—that became one of the ultimate taboos.  And this anti-cannibal message gets spread not only through organized religion but also through popular literature.

GRABER: But if you’re not part of the Judeo-Christian tradition, you won’t necessarily share these world views.

SCHUTT: Culture is king. If you don’t get spoonfed through, you know, the ancient Greeks through the Romans and then the Shakespeare and the Brothers Grimm and Daniel Defoe that cannibalism is the worst thing that you can do to another person—if you don’t get that story, then you don’t have this knee jerk reaction that we all have now in the West about cannibalism and how horrible it is. In other cultures that did not get that as the party line, they developed their own rituals and medicines and practices and warfare and burial rites that sometimes involved cannibalism. And it wasn’t wrong to them, it was, you know, this was a ritual that they developed and and sometimes this is what they did to their loved ones or this is what they did in warfare. Or this is what they did when when they ran out of food or as a way to pay homage to their sick relatives.

GRABER: And this is exactly what happened in China. As we’ve said, the Chinese kept amazing records, so we have a better idea of what was going on there. It’s important to remember that these practices certainly weren’t limited to the Chinese.

TWILLEY: But there’s this Confucian concept in China to do with filial piety. Basically respect and care for your elders is really really important.

SCHUTT: In its extreme form, what would happen is that, if you had an elder or a relative who was very sick, that you would cut off a part of your own body, usually a part of your arm or a part of your thigh, and feed it to them as a sort of last resort medicinal treatment. And you know this was a fairly well accepted custom to the point where they had to make special laws so that people wouldn’t pluck out an eyeball or do something that extreme and feed it to grandma or grandpa.

GRABER: This is a form of what’s called medical cannibalism. And it’s not the only one in ancient China.

TWILLEY: Chinese scholars have documented the consumption of human organs and human flesh to cure diseases as far back as the Han dynasty, nearly 2000 years ago. Doctors would prescribe human bones and hair, but also toes and liver to their sick patients.

GRABER: But don’t let our Western taboo against cannibalism blind you here—Westerners also thought that consuming their fellow humans would help them get better.

TWILLEY: We called Shirley Lindenbaum about this, she’s a medical anthropologist. She’s Australian although she’s now based in New York.

SHIRLEY LINDENBAUM: That was also very old, as long ago as Pliny who thought drinking human blood was good for epilepsy. And then medicinal cannibalism was widely practiced, including not just blood but other body parts in Europe, from the sixteenth to the eighteenth century.

SCHUTT: This surprised me, given the taboo that we have in the West—that medicinal cannibalism was very, very common in Europe. Starting in the middle ages throughout the Renaissance right up until the beginning of the twentieth century, just about every body part you can think of was used for you know to treat any type of disease that you can think of. Kings were doing it, people who were rich were doing it, the poor were doing it. Everyone. For example, they would grind up bones. People would line up at at executions to collect blood.

GRABER: Like Pliny, they thought it’d help them cure epilepsy. Epileptics would literally carry a cup along to executions. And parts of the prisoners’ bodies were cut off for medical use, sometimes when they still alive. And this next one might be my favorite weird example of all.

SCHUTT: Mummies were ground up. So there was a real run on Egyptian mummies and it was all because of a mis-translation. There was an Arabian word called mumia, and that was this kind of tarry bitumen substance that they would use to bind wounds and they were also used in mummy preparation. But the Europeans mistranslated it. They thought mumia meant mummy. So they’d bring mummies back from Egypt and grind them up into a powder. It was actually sold on the Merck index into the 20th century, which to me was amazing.

TWILLEY: Western medical cannibalism fizzled out mostly after the Enlightenment and the dawn of modern medical science. But like Bill says, ground up mummies were sold into the twentieth century.

GRABER: And then there’s an example I had heard of but had never thought of as cannibalism that went on until only a few decades ago.

LINDENBAUM: There’s a kind of medicinal cannibalism in cadaver-derived drugs. Taking out pituitary glands, for example, for body building and for hormone growth in stunted children. That came to an end—that went on from about the 1960s to the 1980s.

TWILLEY: But there’s one last form of medical cannibalism that still goes on today. The final frontier.

SCHUTT: Yeah, I think placentophagy is probably the last remnant in the West of medicinal cannibalism. The belief is that by consuming your placenta after you give birth that you are in some way obtaining a medicinal benefit. Generally speaking the person believes that they are replenishing hormones that are lost, estrogen and progesterone that are no longer being produced by the placenta, which goes from a miracle organ to after birth quite quickly. And so there’s this belief that it levels out the ups and downs of postpartum depression.

GRABER: I frankly had never heard of anyone doing this—I think maybe I heard of some celebrities but I probably tuned it out.

TWILLEY: Oh my god, Cynthia, only Kim Kardashian West just ate her placenta for crying out gently. Where were you?

GRABER: I missed that. Nicky, though, you had a more personal connection.

SARAH RICH: Yes. I got a note from Nicky asking if I knew anybody who had consumed their own placenta. And I said I know someone very well. In fact, I have done that twice.

TWILLEY: This is my friend Sarah Rich. You might remember her as the proud owner of gold-plated flatware from our very first episode. She’s also a talented writer and editor, we have a link to her awesome new book Leave Me Alone with the Recipes on our website. It is gorgeous.

GRABER: When Sarah was giving birth to both of her children, like a bunch of her friends in the East Bay, she used a doula not only to help her with the delivery, but also to help her with her placenta.

RICH: She brings a cooler to the hospital, and when you give birth in Berkeley, which is where I did, I think maybe the hospital staff isn’t totally stunned when the request comes along to take the placenta in a cooler home. So that’s what she did. She took it like I think you would transport any organ in a cooler. And yes, she has a set up at her home where she dehydrates it and then grinds it up and encapsulates it. And she brought it to me in a little glass jar a few days later when she came to check on me. And so yeah, I took a capsule once or twice a day.

TWILLEY: As Bill said, one of the things that motivates new mothers to eat their placenta is a belief that it will help ward off any postpartum depression. And that’s what motivated Sarah too.

RICH: I think for me the primary one was a curiosity to see whether it would have a positive effect and a fairly certain notion that it would probably not have a negative effect and that if anything it might have a placebo effect, which was fine with me.

GRABER: In fact, Bill thinks the placebo effect is probably what’s going on. But he says very, very little good research has been done on this practice.

SCHUTT: As a matter of fact some of the research that’s been done indicates that if anything at all it may have an analgesic effect. It may act as something that enhances the body’s own opioids. But if you’re not eating it till two weeks after your baby is born then there’s really no effect there. But if you’re looking at this thing as a way to replenish hormones, as soon as you cook it, you’re denaturing those hormones.

TWILLEY: Now cooking may not be rendering them completely inactive—some research shows that it’s possible to be exposed to hormones in meat after cooking.  It’s also possible that drying and grinding would have a less destructive effect.

GRABER: There really hasn’t been any good research on this, and, as of yet, none showing that eating your placenta affects hormone levels after birth.

TWILLEY: But you know what, the placebo effect is one of the strongest drugs out there. And, either way, eating her placenta seems to have worked for Sarah.

RICH: Well, I don’t think I experienced postpartum depression, and so, in as far as I could say it helped me avoid postpartum depression….maybe it did? I don’t know.

GRABER: A lot of doulas say that eating your placenta is a quote natural thing to do. And yes, some non-human animals do eat their placentas after giving birth.

SCHUTT: There are various hypotheses for why that might be so. For example, if you give birth and then you get rid of the after birth, it’s not going to attract predators. And it’s also a nutritional boost. You’ve just gone through this stressful period. The last thing you want to do is go out hunting and there’s this big slab of meat. And so it sort of makes sense in the animal kingdom. But it doesn’t make a whole lot of sense in humans. And so it’s not surprising that you don’t really see a lot of it.

TWILLEY: Although Shirley has seen evidence of it in her anthropological work with remote tribes. But it’s not common.

GRABER: Bill says this practice really became slightly more popular among humans only in recent decades.

SCHUTT: And so what started out as sort of a rarely performed sort of hippie thing back in the 60s, relatively recently has turned into something a bit more as a facet of alternative medicine

TWILLEY: A lot of placenta eaters take the pill route, like Sarah did. And pills are relatively tame, honestly although Sarah said hers didn’t smell great. But some women choose to eat the placenta as a meat. Bill was curious, so he called a doula named Claire to find out more

SCHUTT: I gave her a call. And we got along really well, I figured OK, well, maybe we’ll Skype or Facetime or phone interview. And she said, well that’s too bad because I just gave birth to another child and if you came down here you could eat my placenta. My husband’s a chef. We could prepare it any way you want it. We could make, you know, we could make a taco out of it or you can have it osso bucco. And I’m going, what? I’m thinking to myself, you just invited me down to Texas to eat your placenta!

GRABER: I have to admit that at this point in the interview I was having a bit of a tough time listening. I honestly did not want to hear about Bill eating this woman’s placenta for dinner with her family. But he did, and he told us about it.

SCHUTT: He prepared it osso buco-style and I cleaned my plate. I would never do it again but it was certainly something that I’m glad I did.

TWILLEY: So of course I wanted to know, what did it taste like?

SCHUTT: It had the consistency of veal and it tasted—this is not the most popular food but what I thought of immediately was back when I was a college student, we used to get together on Sundays and everybody would  watch football and we’d throw a bunch of real garbage-y food together. And people would cook up chicken gizzards. And it reminded me of a chicken gizzard, the taste. Sort of an irony, organ meat-taste. It was kind of tender. It reminded me of veal that tasted like a chicken gizzard. That’s about as close as I can get to a description.

TWILLEY: So now you know. But you might be thinking, how is this cannibalism? Sarah certainly didn’t think of it that way.

RICH: It felt to me like eating a part of my own body. And I didn’t really frame that in my head as cannibalism.

GRABER: But in Bill’s definition of cannibalism, eating parts of your own body counts.

TWILLEY: What’s more, the placenta is part fetus. So that’s more like the parents-eating-the-kids version of cannibalism. Part of the kids anyway. Sorry Sarah.

GRABER: So placenta eating, and Chinese filial piety, the Europeans and mummies—these are all forms of medical cannibalism. Another common form of cannibalism, common at least where cannibalism is practiced, is ritual. Like James said, rituals around warfare and religion and burial.

TWILLEY: And that brings us back to Shirley Lindenbaum, the Australian medical anthropologist.

LINDENBAUM: So in 1957, a colonial government physician called Vincent Vegas noticed this new disease.

TWILLEY: And the disease is killing lots of indigenous Papua New Guineans called the Fore people.

SCHUTT: Once the press got a hold of it they started to call it the laughing death or the laughing sickness. And no one knew what it was from. Some people thought that it was from stress-related contact with Westerners. Other people thought it was toxins that they were getting into their system somehow.

GRABER: Another theory was that this laughing sickness—”laughing” because people basically just lost their minds—that it was a genetic disease. This is where Shirley comes into the story.

LINDENBAUM: So in 1961, the Department of Genetics asked me and my husband then, John— uh, Bob—to go to Papua New Guinea and collect data about Fore social life. And in particular they wanted kinship studies because they were interested in the genetics of the disease. I was in my 20s.

TWILLEY: So Shirley and Bob—yes, they have since divorced—they traveled around Papua New Guinea. And they quickly realized that the genetic theory just didn’t hold up. Because the people who were getting sick were not related in the biological sense. The Department of Genetics had got confused because the Fore had these elaborate non-biological kin structures.

GRABER: The people Shirley spoke to remembered some of the earliest cases of this disease, which by now was called kuru. They even remembered the names of the people in their communities who first died from kuru.

LINDENBAUM: So we said, what happened to them? And they said, well, we ate them. So we said, you ate them? We knew they were cannibals but we didn’t know that they’d eaten the kuru victims. So we thought, well, we had better change our study a little bit here.

TWILLEY: Shirley eventually learned that when a Fore woman died, the tradition was that her husband’s family had to hold a massive feast for her funeral. And as part of that feast, they would eat the dead person. The entire dead person. Including the brain, which was mixed with ferns and then cooked.

GRABER: There are a couple of reasons the Fore performed these funeral rites for their dead. One was to get rid of the dead person’s spirit.

LINDENBAUM: So the Fore thought that there was the spirit of the dead person still hovering over the body and if that person had been maltreated or had a grudge against any of the people it would bring problems to the husband’s lineage.

TWILLEY: Eating the person meant the spirit couldn’t do any harm. The women even thought it might make them more fertile. And the other reason was—well, the belief was that the dead woman had given children from her body to her husband’s family. She had enriched her husband’s lineage with new bodies. So her original family—the idea was that they should be paid back for that gift by at least having the chance to eat her body now that her husband’s family wasn’t using it anymore.

GRABER: Shirley figured out that the disease was caused by cannibalism because only women and children were getting the disease. And only women and children ate the dead bodies.

LINDENBAUM: We went to the Kuru conference in Adelaide, told everybody what we thought. Nobody believed us.

TWILLEY: But eventually medical science proved Shirley right. For one thing…

LINDENBAUM: We now see that nobody born since 1960 has ever come down with the disease. And 1960 was the time when the missionaries and the government officers went through on patrols and said, “You’ve all got to stop fighting, men and women should live in houses together, and you’ve got to give up cannibalism.”

GRABER: The reason this whole story is important is that this is how we learned about prion diseases, which are caused by eating brains of your own same species. There was a Nobel prize for this discovery. Turns out, kuru is basically the same disease as mad cow disease, which you might have heard of, which cows got from eating other cows’ brains in their feed.

TWILLEY: And which is the reason I can’t give blood in America, because I grew up in England eating these potentially contaminated hamburgers. What’s a little scary is no one knows how long mad cow disease takes to develop. So watch this space.

GRABER: Like Bill said at the beginning of the show, cannibalism definitely has some pretty serious risks associated with it.

TWILLEY: But for the Fore it was important. It was the right way to treat the dead.

SCHUTT: You know, there were examples of this happening back in the 1960s and 70s, anthropologists would go into South America, for example, and they would come across a group that had little contact with Westerners. And these people were just as freaked out to learn that that Europeans were burying their dead as the anthropologists were to learn that these people were eating theirs.

GRABER: Cannibalism is, as we said, a serious taboo in the west. And so when Westerners come across people who do practice cannibalism, those people are often labeled primitives or savages.

TWILLEY: In fact, this is the likely origin of the term cannibal exactly this sort of prejudice. The word cannibal only came into use in 1553. Before that, humans who ate humans were called anthropophagi.

SCHUTT: There are a couple of different possible origins for cannibal. And that it is a corruption of one of the indigenous groups of the Caribbean who were called the Caribs. There are certain researchers who believe that Canib is a sort of a distorted way of pronouncing Carib.

GRABER: There are other theories, but this one seems to be the most likely—that it’s what the Spaniards called the inhabitants of islands in the Caribbean.

SCHUTT: This was one of the most horrifying aspects of the book. When Columbus came over—he made four trips to the New World, and on his first trip, the people that he ran into in the Caribbean were described as kind, many of them, and they were fit to become good Christians. And he reported this back to Queen Isabella. And you’ve got to realize that what he was looking for was gold and when he didn’t find gold then in a sense the next best resource became humans—slaves. And so the third and fourth trips back to the New World were, in a sense, they were armed invasions. And all of these groups that had previously been described as you know kind and nice people, we got along with them, they were beautiful—all of a sudden, they were cannibals. And Queen Isabella had said to him, listen, you’ve got to treat these people well but if they’re cannibals then all bets are off. And lo and behold on the third and fourth trip: What a coincidence! No gold but plenty of cannibals.

TWILLEY: And if they were cannibals—well, Columbus had been told exactly how to treat them.

SCHUTT: And so that justified stealing your land, stealing your property, raping, killing, hunting you like you were a dog. And it’s because they were able to to justify this by saying well, these weren’t humans, they were cannibals.

GRABER: There’s debate about whether the native Caribbeans were even eating other people. Some say no. Others say it was a funerary practice, just like with the Fore.

TWILLEY: Either way, that didn’t stop colonial powers from using it to exploit and subjugate thousands of native people.

GRABER: But even if the locals were practicing funeral cannibalism, they certainly aren’t today. Almost no one is. Anywhere.

SCHUTT: I think because of the influence of Western culture that if it does take place that it’s done in private and it’s probably done a lot less often then than it ever was before. And I believe that this is because of the major influence that the West has had on many cultures. So if you found a culture someplace that was untouched by Western civilization—and how many of those are there?—then you probably, you may find people who haven’t heard from the guys who hand the T-shirts out that cannibalism is the worst thing you can do, that you need to stop doing that.

GRABER: Which—and I’m the squeamish one here—is not necessarily a sign of world improvement. Remember, some communities thought we were barbarians for putting our dead in the ground and burying them. It’s just a different mindset.

TWILLEY: But perhaps because actual cannibalism is rare today, the few cases we do see are the crazy gory sensational ones. You get the serial killers, you get Ed Gein—he’s the one Hannibal Lecter was based on. You get Jeffrey Dahmer, you get that German guy who advertised for a person to eat online. And then ate him.

SCHUTT: There’s a spectrum of criminality and mental illness that that winds up on occasion manifesting itself in murder and cannibalism.

TWILLEY: We are horrified by these people and yet, judging from the movies and the news coverage and the books, we are also kind of fascinated.

GRABER: Another thing we love? Zombies. Who also eat people. There’s the Walking Dead and the Santa Clarita Diet, and my personal favorite, the murder-solving brain eater in iZombie.

(iZombie theme music)

TWILLEY: See, Cynthia. You act all squeamish but you love cannibalism really.

GRABER: I close my eyes every time she eats brains. But she is really funny.

TWILLEY: We asked Bill why he thinks cannibalism has such a hold on our imaginations these days. He wasn’t sure, but he had a theory.

SCHUTT: When I think about that, I think of, take the number one Western taboo arguably and now add food. Right? And so you’ve got something that is fascinating.

TWILLEY: This episode was suggested by one of my favorite listeners, my husband Geoff. And to Geoff, the fascination with cannibalism is not just that you’re mixing a taboo with one of the most fundamental substances to our survival: food.

GEOFF MANAUGH: It’s that you are food.

TWILLEY: Geoff has been giving me cannibal books as a not-so-subtle hint for at least a year now. Seriously, I have quite the cannibal library. So I asked him why he wanted Gastropod to make a cannibalism episode.

MANAUGH: I think what’s interesting to me about cannibalism and its relationship to food is that we become the thing being hunted or we become the prey. And it’s such a powerful motif in horror, from movies like “Jaws” where human beings become food for animals or even “Jurassic Park” where we’re being hunted by these resurrected dinosaurs. When you have the figure of the cannibal, it’s this other human life form that wants to eat us, we become food and lose all of our power and I think that’s the origin of the horror of cannibalism.

GRABER: Happy Halloween!

(MUSIC)

TWILLEY: Thank you, Geoff!

GRABER: Yeah, thanks Geoff. Thanks to Bill Schutt, author of Cannibalism: A Perfectly Natural History.

TWILLEY: Thanks also to James Cole and Shirley Lindenbaum, we have links to their papers, books, and research online. And a particular thanks to my friend Sarah, we have a link to her new book on our website at gastropod.com. It’s gorgeous and you should check it out!

GRABER: And thanks as always to our amazing volunteer, Ari Lebowitz. We promise that in two weeks we’ll be back with something much more appetizing.

TWILLEY: Meanwhile, we’ll let James have the last word this week.

GRABER: And is your calorie count for this average man raw or cooked.

COLE: Raw. The calorie values would change when cooked, but I really didn’t have any way—or much desire I have to admit to try and explore that option.

This is a transcript of the Gastropod episode V is for Vitamin, first released on April 11, 2017. It is provided as a courtesy and may contain errors.

(FLINTSTONES VITAMIN JINGLE)

CYNTHIA GRABER: Once I get that jingle stuck in my head, I can never get it out. Those of you who grew up in the U.S. will probably recognize it—that song is trying to make sure parents bought and gave us our daily…

NICOLA TWILLEY: Vitamins! And I’m sorry folks, I’m going to say it that way throughout. Even if our guest this week did make fun of me for it. Because that’s what we’re going to be talking about this episode: vitamins.

GRABER: Or vitamins. We’ll forgive you, Nicky, your native British pronunciation.

TWILLEY: Either way, we both need them. We all need them. But what are they?

GRABER: And how did we figure out what vitamins are, and why need them? That story involves chickens, doughnuts, and, yes, the Flintstones.

TWILLEY: Plus some news you can use: are we getting enough of them?

GRABER: All that and more this week on Gastropod, the podcast that looks at food through lens of science and history. I’m Cynthia Graber.

TWILLEY: And I’m Nicola Twilley. But first, we want to tell you about some of our sponsors this episode.

(PRE-ROLL)

GRABER: But, before we get back to vitamins, we want to tell you about the survey that so many of you helped us out with. A huge thanks to all of you who filled it out—we exceeded our goal! You provided lots of super helpful information, and it’ll help us support the show and make it better.

TWILLEY: So we wanted to share some of the findings with you. Some of you asked for transcripts of episodes. Guys, we have those! They don’t go up right away, because they are created by our fabulous volunteer, Ari Lebowitz, but you will find them about two weeks after an episode goes out, at the bottom of that episode web page. Check ’em out.

GRABER: Next, lots of you wanted us to do more live events. The great news is, WE want to do more live events, too! But we need someone to invite us and pay to host the show. It can be a local science festival. Or a museum. Or maybe your company wants some live entertainment. Or you’re helping organize a conference and want to hire us to perform there. We would love to.

TWILLEY: We also heard from you that you want more episodes, like every week. Here’s why that’s not going happen, at least for now: I would die and Cynthia would too. You guys know it’s just the two of us—and the research and interviews and writing and mixing for this kind of show, it just takes time. Some of you seem to think we’re part of a network, like Radiotopia, but we’re not. We’re independent, so everything is on our plate and our plates are pretty full right now. Sorry.

GRABER: And now on to our ads. Some of you love how we script our ads—thanks! We try to keep them entertaining for you. Glad to know it’s working. But some of you weren’t crazy about having to listen to ads, especially if you support the show. So, to be transparent: so far, ads bring in about half of the budget that the show needs. That’ll grow as we get bigger, of course. But it’s just half. Our stretch goal is to raise another about 15 percent of our budget from donations. We’re not there yet. But of course we really appreciate everyone who’s already donated this year. And then, you know, we’re working hard to make up the rest from grants, live performances, and so on. So ads are here to stay. We need them. We hope you enjoy the quirky ads we—that is, Nicky, she’s the ad genius—that she writes for you.

TWILLEY: My own humble contribution. So, final couple of things we wanted to share. One, we found out that 20 percent of you—that’s 1 in 5 people listening right now—found out about this show from a friend. This was really really exciting. I mean, if all of you went and found one more person to share Gastropod with, we’d be well over our listener growth goal for the year. I would do a little dance.

GRABER: On video?

TWILLEY: No, the reward is you don’t have to see it. But, seriously, keep telling your friends. This is working! And then final thing for now: we have a new reward we want give you for supporting the show.

GRABER: We have really fun Gastropod stickers for you. They’re available if you give $1 per show or more on Patreon or a $20 or more donation on our website, Gastropod.com. And if you’ve already given and you want a sticker, email us at [email protected] Thanks again to all of you—we appreciate your feedback, your support, and of course, your listening!

(MUSIC)

GRABER: So, to help answer all our vitamin questions, we turned to an expert.

CATHERINE PRICE: My name is Catherine Price and my book is Vitamania: How Vitamins Revolutionized the Way We Think About Food.

TWILLEY: OK, we have our expert. Let’s start with something basic, like what is a vitamin.

GRABER: Except it’s not quite so basic.

PRICE: The tricky thing about providing a standard definition of a vitamin is that technically there really isn’t one. But, for the purposes of not totally confusing us right from the beginning, you can say that a vitamin is a substance that we need in very, very small amounts in order to prevent a particular deficiency disease and the substance is found in food.

GRABER: So, sticking with the basics, how many vitamins are there?

PRICE: So the the list of vitamins today would be A, B, C, D, E, and K. And there are eight B vitamins that go by other names like niacin or thiamin and riboflavin—things like that. But there’s 13 total human vitamins.

TWILLEY: These 13 vitamins—they are our cast of characters today. And really, they’re kind of VIPs. I mean, we would die without them, that’s how important they are.

PRICE: We need vitamins because they help make reactions happen. And they do so by helping to create or help facilitate these things called enzymes, which are large protein molecules that help chemical reactions speed up by multiples—I mean, up to millions, millions of times faster than they would on their own. And that keeps life going.

GRABER: Here are some of those chemical reactions we completely rely on vitamins in food to make happen: regulating our body temperature, excreting waste, synthesizing DNA, building and breaking down muscles and bones. Blood clotting. Energy production. The creation of the chemicals that allow our nerves to communicate—and that means they’re keeping our brain functioning.

TWILLEY: Basically everything. If all these reactions were left to run at their own speed, without enzymes, life would grind to a halt and we’d die. Enzymes speed them up, so that’s good. But the body needs vitamins to build these enzymes. So the next question is, where do we get these magical substances?

GRABER: We get almost all of these vitamins from plants. But why are plants making them in the first place?

PRICE: Obviously, plants don’t eat food. They get their energy from the sun and from water and they have chemical reactions called photosynthesis that creates energy that they can use to grow and store energy. So plants need vitamins to catalyze those reactions for themselves, just as we need vitamins to help with reactions in our own bodies.

TWILLEY: Plants are great at making useful chemicals and they can make all of the vitamins except for D and B12. Humans are not so good but we can make vitamin D, actually. Which is weird.

PRICE: Vitamin D is weird for many reasons, but that one, you know, we typically think of vitamins as things you need to get from food. But humans actually are totally capable of producing vitamin D in response to sunlight via a chemical reaction in our skin. And in fact that’s probably the way we were meant to get vitamin D because it exists in very very few animal products or food products at all.

GRABER: One of those 13 vitamins we need doesn’t come from plants or sunlight—we get it from meat. That’s B12. And actually, it’s in meat because it’s made by bacteria. All the B12 in the world is made by bacteria. The animals like cows and clams that we get it from, they absorb the B12 that the bacteria in their guts make.

TWILLEY: As it turns out, we humans also have vitamin B12-producing bacteria in our guts. But, sadly, they live in the end part of our guts, after the part of the intestine where B12 can actually be absorbed. There are a few other animals like us, including rabbits and gorillas. We’re called hindgut fermenters, technically. Anyway, rabbits get around this B12 problem by eating their own poo. Humans tend to get around it by eating animals. Or supplements.

GRABER: Good thing, too. So this is why for cows, B12 isn’t a vitamin, because their body makes it naturally from bacteria. A vitamin is something you have to get from eating food.

TWILLEY: Our distant, distant, distant ancestors—I’m talking single-celled organisms here—they could make all the chemicals they needed for metabolism. So there was no such thing as a vitamin for them.

GRABER: Over billions of years of evolution, and through the evolution of animals and plants, we—we eventual humans—we lost those abilities to make all those chemicals, because we can get them from our environment. Vitamin C is an interesting example.

PRICE: Scientists hypothesize that humans probably did have the capacity to make some of the substances we call vitamins in the past. And the one that’s usually brought up is vitamin C because we technically have the genes to create it but there’s a disabling mutation that makes us not be able to make it. And the general theory is that we may have evolved to not make our own vitamin C because we were surrounded by plentiful sources in nature, since vitamin C is contained in, you know, fruits and vegetables.

GRABER: All that vitamin C that we need from fruit and the vitamin B12 from meat in our diets—it’s all crucial to our survival. But even though we cannot live without them, the amount of each vitamin that we need to to power our bodies is vanishingly tiny.

PRICE: Vitamins are extremely, extremely hard to measure because they exist in minute quantities, like fractions of a salt crystal, for example. Crazy small.

TWILLEY: The amount of vitamins in foods is often so, so tiny that it can’t even be weighed. You have to figure out how much of the vitamin is there by how fast a bacteria that eats it grows. That’s how crazy small these amounts are.

PRICE: So that was another obstacle and challenge in the discovery of vitamins was that they really were essentially invisible.

GRABER: We take vitamins for granted, it’s hard to imagine that there was ever a time that we didn’t know about vitamins in our food. But they’re a really recent discovery.

TWILLEY: And the story of that discovery starts in Southeast Asia, in the 1800s.

PRICE: So in Southeast Asia, particularly in the mid to late 1800s, this mysterious disease started popping up called beriberi, and it involved nerve damage and then also cardiovascular issues and killed people also in grotesque, painful, and horrible ways, much like scurvy.

TWILLEY: Ironically, beriberi really only started being a huge problem thanks to technological innovation. That’s actually true of most vitamin deficiency diseases. Catherine mentioned scurvy—we covered that in our citrus episode. That’s a disease caused by a lack of vitamin C. Scurvy didn’t become a huge problem until better sailing and navigation technology meant that ships could be away from shore for months at a time and people weren’t eating fresh fruit and vegetables.

GRABER: In beriberi’s case, the disease only became a huge problem after the invention of better rice-milling technology.

PRICE: So this started to really become an issue after the invention of better rice-milling technology, meaning that technology that would automatically remove the rice husk and leave behind just the white rice that we typically eat today. So in cultures where rice was a main substance in the diet, there started to be this outburst of this mysterious and horrible disease.

GRABER: People in Asia are wondering: what is causing this horrible disease? At the same time as beriberi is exploding, in Europe, scientists are discovering that there are these tiny, microscopic creatures called germs that can cause diseases.

PRICE: And that caused a huge amount of confusion in terms of the search for the source and the cause of these deficiency diseases, because people started to look for a bacterial cause of things like beriberi and scurvy.

GRABER: Take a second here and think about this problem. To understand vitamin deficiency diseases, you have to understand that food contains vitamins—these are invisible substances that are essential to your health. Lots of people are trying to figure out what’s causing beriberi. Almost all of them are looking for a thing—a germ or an infection that causes the disease. They’re not looking for a thing that’s missing. There isn’t even the concept that this could be a problem.

TWILLEY: This is a recurring thread with vitamins. Until you have the idea of a deficiency disease, you can find the cure for the symptoms, but you won’t understand what’s actually going on.

GRABER: OK. Back to Southeast Asia in the late 1800s. Specifically Indonesia, which was a Dutch colony at the time. Lots and lots of people are dying of beriberi.

TWILLEY: And so the Dutch send over a doctor called Christiaan Eijkman to figure out what the hell up.

PRICE: And he comes over and he’s told to try to figure out what beriberi is and what causes it and how to cure it. And so his assumption is that there’s a bacteria. So he starts by getting a population of chickens, which he chose kind of randomly, and it happens to be very lucky that he did because chickens are one of the animals that are most prone to beriberi.

GRABER: Not all animals need to get thiamin in their diet, so not all animals suffer from beriberi. Chickens do. Not that Eijkman had any idea about any of this.

PRICE: So he picks chickens and then he divides them into two groups and he injects one group of chickens with blood from people who had beriberi to see, because that presumably would give them beriberi. So he sits back and watches and those chickens do start to get beriberi-like symptoms. But then he notices the control group is too, so that’s confusing. So then he says, OK, well, that maybe that’s because bacteria are transmitted by air and these chickens are too close, so we need to separate the populations and put them in separate cages in different rooms. So he tries various permutations of this. But the control group keeps getting sick. And then at some point, he does an experiment with the chickens in separate rooms and they don’t get sick. Neither group gets sick.

TWILLEY: What the what?

PRICE: And what’s more, the chickens that had been sick all get better. Which to me is just like, I mean, what would you do if you’re that researcher or you took I don’t know how much time infecting the chickens with supposed beriberi and it just goes away—like, it all just goes away? You start to think you’re delusional, like, did that really happen? And to his credit he didn’t just throw up his hands.

GRABER: Instead, Eijkman kept his scientific cool and tried to figure out what was different.

PRICE: And he happened to speak to this laboratory assistant who said, well, you know, in the beginning of the experiment the chickens were being fed rice but they were being fed a special kind of rice. They were getting the leftovers from people and the leftover rice was white rice. And then at some point, word got around that the chickens were getting this fancy rice, because that was a fancy, expensive kind. And they said you shouldn’t be giving that to lab chickens. Go back to the regular rice. So the chickens had been given regular rice, which was the kind that was brown and that still had a lot of its husk on it. And that happened to coincide with when the beriberi-like symptoms disappeared. So that gave Eickman the idea that, wait a second, maybe there’s something about the food that’s making a difference here.

TWILLEY: So now he needs to test this theory on humans. After all, he’s not even completely sure chicken beriberi is the same disease as human beri beri.

PRICE: And you can’t really ask the chicken the same diagnostic questions as people.

GRABER: It happens that Eijkman had a friend who ran a bunch of prisons, and they happened to serve the prisoners different kinds of rice. So he and his friend figured, let’s see what the rates of beriberi are in each prison and compare them to the type of rice the prisoners were eating.

TWILLEY: And basically the deal was in the prisons where men were getting just white rice, a quarter of the prisoners had beriberi, and in the other prison where it was brown rice on the menu, only 1 in 10,000 got the disease. So brown rice clearly had something that Eijkman called anti-beriberi factor.

PRICE: So you think, great. Like, he must be a Dutch hero. But, no, he didn’t get that response. He got mocked by his colleagues.They said, you know, I can’t believe it took six years to come up with such a stupid hypothesis, and, like, basically skewered him. Said that he must be suffering brain damage himself because of eating too much rice.

GRABER: His colleagues just couldn’t imagine that anything other than germs could cause disease. Eijkman had to be nuts.

TWILLEY: Eventually, Eijkman got a Nobel prize for his efforts, but it took a long, long time for people to accept that beri beri wasn’t caused by germs but instead by a nutritional deficiency. Eijkman’s anti-beriberi factor goes on to become the first vitamin ever found: thiamin.

GRABER: But finding and naming thiamin took another couple of decades. Thiamin was the first vitamin discovered, but for all of the vitamins, the discovery process took a long time.

PRICE: So it requires multiple steps of recognizing that such a thing exists, and then actually chemically isolating it. So, using tons—I believe it was literally tons of rice husks—to crystallize a tiny bit of thiamin so you can look at a substance and say that is thiamin or that is vitamin C. Then you need to understand the chemical structure of it, and then you need to be able to reverse engineer it, to be able to create it. And that last step, to give you a sense of how recent this all is, vitamin B12 was only figured it out in terms of actually its chemical structure in the 70s.

TWILLEY: So identifying and isolating vitamins actually took an extraordinarily long time, for each and every single one. But there’s something else kind of shocking about this whole thing, and that’s how recently the word vitamin was invented. It’s barely a hundred years old.

PRICE: The history of the word vitamin to me is one of the most fascinating things I found out when I was researching the book. Because when I started out I just thought that had been around since time immemorial and that—you know, it just seems so familiar. It’s like air, so how could that possibly be a new creation? So I was shocked when I found out that actually the word vitamin only dates to 1911. And when it came out people didn’t accept that as a word.

TWILLEY: The reason they didn’t accept vitamin as a word is that it was totally made up.

PRICE: And the story there is that there was a Polish biochemist named Casimir Funk. It’s a great name.

GRABER: Funk was studying beriberi. And, unlike everyone who was obsessed with germ theory, Casimir Funk—like Eijkman—he thought that beriberi was caused by a deficiency in some mysterious nutrient that nobody had found yet.

PRICE: So he went a step further than his colleagues though because he decided he was going to give it a name—give the substances a name. So he took the Latin word for life which is vita, and then he took the word amin or amine, which is the chemical structure that he thought that all these substances were going to share. And he mashed them together and he came up with vitamine, or vitamine—it probably was vitamine at that point. And it had an e at the end.

TWILLEY: Vitamine. Or vitamine. I kinda like it.

PRICE: So Casimir Funk loved his new word vitamine and he really wanted to get it into the public. But he was having trouble because his medical colleagues didn’t think that it was right to just make up a word and start dropping it into medical texts. And so in 1911, he tried and totally failed. It got cut. He had to refer to these things by a much more circuitous manner and it had some horribly boring title. But then in 1912, he figured out a way to get a paper published in a publication that didn’t require the approval of his superiors. And in that one he just started dropping vitamine, like, right and left. I think it appears 27 times in that paper. He just acted like, yeah, it’s a vitamine, like, what’s your problem?

GRABER: So Casimir Funk just threw that word vitamine around in his scientific paper. But it still took a while to catch on.

PRICE: The reason it wasn’t particularly popular in the beginning and it didn’t catch on is that, first of all, vitamin doesn’t refer to—there isn’t actually a technical definition, because as it turned out they’re not all amines and they’re lumped together more because of historical happenstance than they are because of anything chemical. So legitimately they probably shouldn’t be called vitamins. But his competitors’ suggestions were really bad. So there are things like anti-beriberi factor or food hormone or fat-soluble A, water-soluble B. I mean, just these things that were not catchy at all.

TWILLEY: Meanwhile, the general public is starting to hear about these magical new substances. And they like the sound of vitamines.

PRICE: By the early 1920s, you still have multiple words in use to describe the same substances. And the scientific community was having this big debate about, like, are we even going to keep this word because it’s ridiculous and stupid and we probably shouldn’t. But then they realized, well, people seem to be using it, so we better standardized this somehow. So one chemist suggested that they drop the final e because they weren’t all amines, so at least get rid of that controversy. And then he suggested putting the letters on them, because the main alternate way of referring to vitamines at that time was with this fat-soluble A, water-soluble B, water-soluble C terminology. And so that got smushed together and that is how we ended up with vitamin A, vitamin B, vitamin C, vitamin D, that we’re so familiar with today.

GRABER: So that’s the origin of the word itself. And then they’re named after letters of the alphabet. But there are multiple Bs, and a big gap between E and K.

TWILLEY: Did these scientists not know their alphabet? Or what?

PRICE: Vitamin B, interestingly, was originally thought of as one substance. And then scientists started to recognize it was actually eight separate substances. So that’s why we have B1, B2, B3. You may be saying, wait a second, we have a B12 but we don’t have—there’s only eight of them. How did that happen? And that speaks to the other thing that happened with vitamins is that some substances that people originally thought were vitamins turned out not to be vitamins at all. So those just got kind of thrown out. And there’s these gaps, like there’s no B 11, like these gaps in the terminology.

TWILLEY: And by the time this whole process is done and we finally know our vitamins, we enter a brave new world of vitamin donuts and sheep-wool processing factories in China. All still to come after we tell you about bras, bell peppers, and a couple of our sponsors this episode.

(MIDROLL)

TWILLEY: So the other thing that is going on, while scientists are discovering vitamins and arguing about what to call them, is a much larger shift in how we understand and think about food.

PRICE: Another thing that needs to happen before you can conceive of a vitamin is that you need to understand that food can be broken down into parts.

GRABER: First, in the early 1800s, scientists discovered that food could be broken down into three major macronutrients. These are fat, protein, and carbohydrates. This is a big change in how people looked at their food.

TWILLEY: And then by the end of the 1800s, you get the concept of the calorie. We made an entire episode about the history and science of calories, which is truly bizarre—you should listen to that if you haven’t already. But the point is that scientists are measuring and analyzing food in completely new ways: grams of protein, numbers of calories…

GRABER: And now, in the early to mid 1900s, vitamins are the newest addition to the quantification of food.

TWILLEY: And this new mindset of thinking about food in terms of its parts, rather than as a whole—it starts trickling out of the lab and onto American plates.

PRICE: One of the people who was the biggest name associated with vitamins at that time was this guy named Elmer McCollum, who was a research scientist and he did a lot of work on vitamin A and vitamin D. Anyway, he also happened to write a nutritional and health column for McCall’s magazine, which was a woman’s magazine that was very popular at the time. And he was kind of like the Dr. Oz of the 1920s, where he was a respected, medical-seeming figure, and people really took his words seriously. So he started to write about vitamins.

GRABER: And Elmer McCollum—even though there wasn’t much science at the time about the amount of vitamins in food or how much we needed, the whole science of this was far too new—that didn’t stop Elmer. He put the fear of God in housewives.

PRICE: And he basically started to—I was going to say insinuate, but he pretty much said that if you’re not feeding your family, you, American housewife, reading this magazine and not feeding your family a well-balanced diet that has all of these vitamins in it, then you are going to cause your children to develop scurvy and be stupid and maybe blind and all these horrible things, and you’re basically going to cause disaster to fall upon your family. So it caused an awful lot of anxiety among the housewives and the readers.

TWILLEY: Suddenly housewives were supposed to somehow figure out—and remember there wouldn’t even have been nutrition labels on food at this point—I mean, this was just at the dawn of packaged and processed food anyway. But somehow these poor women are responsible for making sure their kids are getting enough vitamin B5, when still today no one knows exactly how much is enough of that.

PRICE: Forget the fact that you had been feeding your family before reading that article and they seemed just fine. You clearly are putting them at risk.

GRABER: Consumers are now worried about vitamins. So, at first, the early processed food companies were not into the whole vitamin thing. But then they saw an opportunity in the fear that Elmer inspired.

PRICE: And they suddenly realized that you’ve got these scientists saying that there are invisible, immeasurable substances in foods, with a catchy name, without which you’ll fall prey to these horrible deficiencies. And no one knows how much of these things you need and you can’t taste them. There’s no way to tell really how much is in the food. So they seize upon this as pretty much like the best nutritional marketing strategy ever, and the one that has really continued to inform the way foods are marketed today. And they start to use the existence of vitamins in their food as proof that the foods are not just healthy but also essential. So you end up seeing these very funny ads for things like canned pineapple, you know, that says, like, every meal should start with canned pineapple. And all these just kind of funny—to our eyes, really funny claims about vitamins.

GRABER: This is all going on before manufacturers could even add synthetic vitamins to foods. They’re just hawking what their food naturally contains.

PRICE: Synthetic vitamins began to come on the scene in the 20s and 30s as people began to figure out what their chemical structures were and then reverse engineer how you can make them. And they caught on pretty quickly. By the time of World War II they were—vitamin pills were widely available. There was a union that negotiated getting vitamin pills as part of its contract. You know, they had “V for victory” vitamin packs. It was definitely the beginning of the vitamin market that we know today.

TWILLEY: So now we have vitamin pills. But, at the same time, vitamins start showing up in processed foods. Food manufacturers add them to everything and anything and then they sell these fortified foods as healthy.

(SUNBEAM BREAD AD)

TWILLEY: My favorite example from Catherine’s book is Schlitz Sunshine Vitamin D Beer, which was launched in 1936 with the tagline: “Beer is good for you, Schlitz with Sunshine Vitamin D is extra good for you.”

PRICE: Or you have breakfast cereals, when the ability to add synthetic vitamins began to be developed—cereals with names like Vitamin Rain. It’s, like, rice shot from guns that has been treated with all these vitamins. And there actually was an attempt to brand vitamin donuts. If you Google the image for vitamin donuts, you’ll see this fantastic picture of these two angelic-looking school children gazing longingly at these donuts with vitamin donuts in big letters in the center. And they actually didn’t get approval for that thankfully. But you can still order prints of it and I have a poster of vitamin donuts in my kitchen.

GRABER: Vitamin Donuts aside, the truth is, the whole processed food industry and the new synthetic vitamin industry—they go hand in hand. You can’t have one without the other. In part, it’s because vitamins are super sensitive.

PRICE: Basically, you can destroy them all sorts of ways. So, by the time you get to the point that you’ve got refined flour that you’re going to use for a Twinkie, that flour does not have very many vitamins in it, and you have to add it back. You have to add vitamins back in.

TWILLEY: And food processing is hardcore—you’re stripping and centrifuging and bleaching and heating. I mean, like Catherine says, in the case of Rice Krispies, you’re literally firing the rice from a cannon to get it to puff up like that.

PRICE: A breakfast cereal is so processed that basically all of its vitamins are destroyed in the processing and then you have to add them back in, by baking them in or spraying them in afterwards to make it nutritionally excusable breakfast. Although, I’d argue no one should eat cereal. But, you know, it’s just kind of like a weird game of taking stuff out and putting it back in. And the question that I began to ask myself is, could we have developed the current food supply, and could we have developed our current food preferences, if it weren’t for synthetic vitamins?

GRABER: This seems like a crazy question, but let’s just go with it. Catherine figured out that in theory, when processed foods and synthetic vitamins were just starting to take over, America had enough vitamins in its food supply through just normal whole foods to feed its citizens. Of course it wasn’t evenly distributed and there was a lot of poverty and malnutrition. But, again, in theory, the American food supply contained enough vitamins to keep people healthy.

TWILLEY: Today, Catherine says, that is not the case, because of the proportion of our food that is processed. Without synthetic vitamins, scientists have calculated that 93 percent of us would be deficient in vitamin E, 88 percent in B9, 74 percent in vitamin A … you get the picture. Processing takes out the vitamin content of foods and most Americans eat a lot of processed foods. So where do those synthetic vitamins that we depend on come from?

PRICE: If you conclude that Americans are dependent on synthetic vitamins in their food supply, then you kind of hope that we make them here, because otherwise that seems like kind of a big vulnerability. If you want to have a crazy thought experiment: if you don’t make enough vitamins in America and whatever country it is that makes them cuts off the supply, then we’re kind of in trouble. Anyway, most of the vitamins are made in China. A lot in India. There’s some manufacturing facilities in Europe. But essentially none are made in the United States. And people often get confused because they think, oh well, there’s all these vitamin pills that are made in the United States. So plenty of pills are put together and formulated in the United States. But the actual raw ingredient, the actual vitamin C or the actual B12, is not made here.

GRABER: Yes, if China cut off our supply of synthetic vitamins, we would be screwed.

TWILLEY: So that’s pretty weird to think about. And how those vitamins are made is interesting too.

PRICE: Essentially, you start with ingredients that you never would think would create a vitamin, like a lot of things come from coal tar. And then you manipulate it chemically in various ways and you end up with vitamin C.

GRABER: Vitamin D is a particularly bizarre one. It links Australia and New Zealand to China and then to American cartons of milk and orange juice. Vitamin D is made from the lanolin, the oil in sheep’s wool.

CP2: So there’s this very interesting industry where lanolin is taken from New Zealand and Australian sheep, shipped to China, purified, irradiated, meaning exposed to ultraviolet radiation, and that prompts the chemical reaction, the same chemical reaction that happens in our bodies in response to sunlight, and creates vitamin D. And then you put into pills or you put it into milk or orange juice and that creates a main source of vitamin D for most people’s diets.

TWILLEY: The vitamin D in your milk or OJ comes from sheep’s wool. It really does.

GRABER: So now manufacturers are tossing synthetic vitamins into food right and left. You see added vitamins everywhere, not just in milk and orange juice and bread but in snacks and desserts and nearly every breakfast food. And then many people top that all off with a morning multivitamin. But how much of these substances do we actually need?

TWILLEY: Well, supposedly there is an answer to that in the form of RDAs. Recommended Dietary Allowances.

PRICE: The RDAs, or the recommended dietary allowances, are fascinating and really confusing. Like, they’re so familiar to us that you’d think that they should represent some true truth, you know, they should be like gospel truth. But the real story about dietary recommendations is that they, too, are a recent development. The first round of the recommended dietary allowances was issued in the 40s as a result of World War II. So there was a desire to try to figure out or quantify how much of the known vitamins people needed to function at their best.

TWILLEY: But what actually happened is that the guy in charge of figuring that out handed off the job to three female nutritionists who were at a conference with him. And he said he wanted them to figure it out by the next morning. Dick move.

PRICE: And so there are these great accounts written by one of the women that was basically, like, the men were off seeing the town and these women are, like, locked in a hotel room being, like, how are we supposed to determine the average person’s niacin requirements? You know, there’s like two experiments on it. Like, what the hell? So they basically came back and were like, we can’t do that, there’s no way to do that. And it became a much bigger project and it evolved into dietary standards and allowances. These were very deliberately chosen words because it worked in a margin of error. And the first ones were developed by basically taking the best guesses based on the evidence of the time and then adding a bunch to it to cover your bases.

GRABER: The science has evolved somewhat since then. But in many cases the standards we use today date to 1968.

TWILLEY: And the other thing is that RDAs are designed to meet the nutritional needs of 97-98 percent of people.

PRICE: What that really means is that most people don’t need that much. And the analogy I like to use with that is it’s like, it’s as if the government needed to knit a sweater in a size that would be big enough to fit ninety seven to ninety eight out of adult Americans. Most people are going to need a far smaller sweater than that.

GRABER: There are problems beyond the size of the sweater with the RDAs. Some vitamins can be stored in our body for a while. Vitamins A and D—we store those in our liver. It’s why you can soak up sun in the summer, create your own vitamin D, and have that vitamin D last throughout the darker winter months.

TWILLEY: And then let’s complicate this even more. Some people genetically have a more difficult time processing and storing certain vitamins.

GRABER: And then there’s our microbiome—all those bazillions of microbes in our guts. They actually create vitamins in our guts that we then absorb. And different people have different microbiomes. Scientists do not have a handle on this individual variation yet.

TWILLEY: So maybe you’re wondering sure, but, bottom line, what’s the harm in taking extra vitamins? More of a good thing has to be good, right?

GRABER: And why stop at a multi? Some people have thought that if if a small amount of vitamins keeps us alive, extra big doses are even better. They’ll cure diseases, like cancer.

PRICE: So things like vitamin C curing cancer, things like that—those not have been proven. And I’d also say that there have been a number of big studies done that seemed like they should have proven that megadoses of particular vitamins like beta carotene, the precursor to A, would have benefits and the opposite has happened

TWILLEY: This is still really cutting edge science. As Catherine pointed out, a couple of decades ago, a big study giving people megadoses of beta carotene to cure lung cancer was stopped when the people taking the megadoses were shown to be not only more likely to get cancer but also more likely to die of a heart attack. But on the other hand, earlier this month, a human trial of megadoses of vitamin C also to cure lung cancer—that was given the go-ahead after the doses were shown not to cause harm. So, basically, the science on megadoses is really not clear. But one thing is certain: more is not always better.

GRABER: But it’s not just that megadoses might be harmful—and they might be—but even regular supplementation? It might also have some unintended side effects. Vitamin B6, or niacin, is known to stimulate appetite. The government started adding niacin to flour in the 1940s. This was important because there actually was widespread niacin deficiency at the time, so that was solved. But researchers have pointed out that extra niacin consumption in our fortified foods—it also correlates with the time that America has gotten more obese. Obviously, a lot of things changed about the American diet at that time, and obviously obesity is super complex. But the point is, vitamins can be looked at like drugs. We don’t usually look at them that way, but they are powerful. And they can have side effects. We don’t know everything that they do in our bodies.

TWILLEY: Because with synthetic vitamins you can take too much—and you basically can’t if you’re just eating normal whole foods, because the quantity of vitamins in foods naturally is so tiny. But the other thing is, food contains hundreds and hundreds of other compounds as well as vitamins. Some we know have health benefits—things like polyphenols and lycopene in tomatoes. Some we don’t know yet, but they could be important.

PRICE: So the example that springs to mind is when I was looking into this company called Neutralite that creates these… they’re not really vitamins, they’re pills, they’re dietary supplements made from concentrated fruits and vegetables. And one of the guys was explaining to me that if you analyze what’s in an acerola cherry, which is a cherry that’s particularly high in vitamin C, you see these spikes for all of these different chemicals in that cherry. Like, there’s a big spike for vitamin C, but there’s all this other stuff, versus if you analyze a vitamin C tablet you’re just going to see a big spike for vitamin C and that’s it. And I asked him, well, what are all those other things that are in the cherry one? And he goes, we have no idea, you know. So I think I think that that speaks to the complexity and the danger of trying to oversimplify.

GRABER: And all these compounds work together in food in ways we don’t understand yet. In a study, rats that were given tomato powder did better than rats given just purified lycopene. There’s synergy in food that we’re still learning about.

PRICE: And, to me, the takeaway with vitamins was to use the historical story and how crazy that story seems to us, because, like, obviously there are vitamins, to then question as being too proud of ourselves in the present and thinking we have figured everything out. Because, you know, a hundred years ago people thought they’d figured everything out and they didn’t even know all the vitamins existed. So what do we not know?

TWILLEY: But here’s my question. Today, more than half of Americans take a dietary supplement of some sort—mostly a daily multivitamin. Should we be?

PRICE: The question of whether take a multivitamin is really common and seems really complicated. But I think you can break it down into some simple, maybe unexpected, questions. The first one is: what are you eating? Are you eating a diet that naturally contains foods that have lots of vitamins? Like, are you eating a wide variety of fruits and vegetables and minimally processed meat and dairy? Are you getting time in the sun so you can get vitamin D? Do you live in a latitude that allows that? Then you’re probably fine. I like to say if you’re eating like the cover of a Michael Pollan book, then you’re probably fine on vitamins. If not, I would suggest you change your eating habits, but you also could take a pill. If you’re eating the way a lot of Americans eat, where you’re eating processed foods that have vitamins added back in, you’re basically eating a whole multivitamin. So in terms of vitamins you’re fine. But you’re probably missing out on everything else that whole foods contain.

TWILLEY: I think a lot of people think of multivitamins as like a sensible insurance policy and a heck of a lot easier than changing their diet. But Catherine points out that pretty much all of the big medical organizations, from the American Heart Association to the American Academy of Family Physicians—they do not recommend that healthy people with no special issues take a vitamin supplement.

GRABER: That said, there are certainly cases where people do need supplementation. We’re definitely not saying that all synthetic vitamins are bad.

TWILLEY: And, of course, there are still deficiency diseases today. Catherine says an estimated 2 billion people around the world don’t have access to adequate vitamins in their diet.

GRABER: But, so, here in the U.S., if you do have access to plentiful fresh foods, you’re probably getting enough vitamins in your diet. You do not have to stress. Still, there are some interesting tips about how to get the most vitamins out of your food, and these tips also, in a happy coincidence, cut down on food waste.

PRICE: Some tips for how to get the most vitamins out of your plants have to do with why plants have vitamins which is basically to protect themselves against the sun. And once you think about it that way then all of the kind of rumors you’ve heard about how don’t throw away the peel of that apple, that has the vitamins—you realize it’s actually true. So outer leaves tend to have more vitamins. Produce that is darker tends to have more vitamins because dark colors absorbs more sunlight, which means there’s more radiation. So romaine lettuce is going to have more vitamins than iceberg lettuce.

GRABER: This is true even if the plant is underground—the outer edges tend to contain more vitamins. So don’t peel your carrots!

TWILLEY: Or your potatoes. Laziness rules.

GRABER: But here one thing that Catherine wants us to take away from her book: the vitamin industry and processed foods literally could not exist without each other. Vitamins enabled our processed food industry, and processed food gave synthetic vitamins a reason to exist.

TWILLEY: And that connection is dark, and it really reveals the dark side of vitamins. Yes, we need them. Yes, it is extremely fantastic not to suffer from scurvy. But the discovery of vitamins and the way that both scientists and food manufacturers talk about them has changed the way we think about food in really unhelpful ways.

GRABER: For one, it’s led us to think about food just as the sum of its parts. It’s reductive. It’s just like my grandma used to say to me when I was a kid, “Eat your potassium, drink your calcium,” instead of eat a banana and drink some milk. But bananas and milk are so much more than just those individual minerals.

TWILLEY: And thinking of food in that way also leads to this incredible arrogance of thinking we can reverse engineer it. The extreme example is Soylent, of course. Which I don’t really want to think about.

GRABER: Because it’s disgusting.

TWILLEY: It is. But the point is, there’s so much we still don’t know.

GRABER: This vitamin craze has also scared us. Elmer McCollum scared 1920s housewives, but we’re still scared today that we’re not going to get just what we need. And so we look for the latest food fad—yesterday, it was canned pineapple, or oat bran, today it’s juicing, or omega 3s, or wheat grass, or resveratrol from red wine. We’re looking for the next nutrient salvation. And we turn to the weirdest, unqualified gurus to help us out.

TWILLEY: Oh my God, don’t even start me. Gwyneth Paltrow selling vitamin C nanospheres and $90 doctor designed vitamin supplements that promise to help you lose weight, feel great and keep all those effing balls in the air. I am quoting GOOP.

GRABER: If we’re not being perfectly clear, we do not recommend Gwyneth’s GOOP vitamins.

TWILLEY: I mean, it’s just horseshit. But it’s incredibly powerful horseshit and a lot of us sort of want that silver bullet.

PRICE: And so that fear element of vitamins coupled with the hope that they contain, even in the word itself—like, vitamin is just such a hopeful word. The fear and hope really created much of our current attitude towards food, and then easily transferred over to where we are today with, like, hemp seeds are this miracle food, or chia. You know, there are these trendy foods that all of a sudden are made to seem like they can cure all ills. And it’s within the broader context of, if we don’t perfectly calculate our diet, something horrible is going to happen to us. So what I ended up concluding is that vitamins are really the beginning of nutritional faith in a way. We all want to have control over our health, we want to know what’s going to happen to us. We can’t actually do those things. But we can put our faith in something. And, as I concluded in the book, you know, in religion you put your faith in some sort of God. And I think that in nutrition we’ve put a lot of faith into vitamins.

(MUSIC)

(POST-ROLL)

GRABER: Thanks to Catherine Price, author of Vitamania: How Vitamins Revolutionized the Way We Think About Food. Catherine’s book contains many more fascinating stories, including much more about dietary supplements, and you should definitely read it. Links on our website, gastropod.com.

TWILLEY: And we’ll be back in two weeks, with an episode all about Japan’s national fungus. Can you guess what it is?

This is a transcript of the Gastropod episode Hacking Taste, first released on March 14, 2017. It is provided as a courtesy and may contain errors.

NICOLA TWILLEY: All right…

CYNTHIA GRABER: Okay, cheers!

TWILLEY: One, two, three…

TINA ANTOLINI: It’s like lemonade.

KELLEY CARTER: It’s so weird! Why is this so delicious? What the hell? Wait, what have you done to me?!

GRABER: So, before one of our Pop-Up Magazine shows, a handful of the crew and performers let us put red pills on their tongues without having any idea what they were taking and what they were in for.

TWILLEY: Hey, we’re good people. And it’s not like we didn’t do it ourselves. But I must admit, it was amazing how easy it was to get people to take pills without telling them what they were.

GRABER: We’ll tell you what those pills were later on, but, for now, what you need to know is that we were screwing with their taste buds.

TWILLEY: That’s right, this episode, we’re going to get to the bottom of our sense of taste: how does it work and how can we mess with it?

GRABER: Why do we taste the things we taste? And can the answers to these questions help us hack taste to tackle some of today’s biggest health problems?

TWILLEY: You’re listening to Gastropod, the podcast that looks at food through the lens of science and history. I’m Nicola Twilley.

GRABER: And I’m Cynthia Graber. And before we reveal the secrets of one of the most important ways we interact with the world, we have some sponsors to tell you about.

(PRE-ROLL)

(MUSIC)

GRABER: So this is kind of a broad question, but what is taste?

ROBIN DANDO: Yep, that’s pretty broad.

TWILLEY: That’s Robin Dando. He’s an assistant professor of Food Science at Cornell University, and he specializes in the study of taste.

GRABER: Taste is one of our five senses. You know the ones: sight, sound, touch, smell, and taste. So taste, like smell, is a chemical sense. Our taste buds are detecting chemicals.

DANDO: The taste bud sits just below the surface of your tongue. We have a few of them around the insides of our mouths as well. But most of them are concentrated in the tongue.

TWILLEY: A taste bud looks kind of like a very tiny little yellow onion. It’s a spherical clump of cells, it has a little bunch of root-looking nerves coming out the bottom, like at the bottom of an onion. And at the top, it has a little hole or pore.

DANDO: Where they branch these little fingers out into the tongue looking for these stimuli.

TWILLEY: Those are like if you left the onion to sprout—those little green shoots, they’re like the taste bud fingers waving around on the surface of your tongue waiting for a chemical stimulus.

DANDO: So a stimulus that’s in solution, something that we either drink or something that we’re consuming and is dissolved in saliva, can activate receptors on the very tips of these cells and cause the cell to light up and send the signal on towards our brain saying that we detect something.

GRABER: The taste buds catch chemicals in a liquid. That’s part of what our saliva does, it takes everything in our food and transforms it into a liquid form.

TWILLEY: Each of the cells at the tip of those little fingers is configured to grab onto different chemicals—chemicals that trigger the basic tastes.

JOHN MCQUAID: You know, you drink a Coke and a sugar molecule comes sweeping by and boom, it attaches itself to a sweetness receptor. And that activates a signal inside the taste cell in the tongue that goes into a nerve and goes into the brain. And you’ll recognize that it’s sweet and it will feel sweet.

TWILLEY: That’s John McQuaid, the author of Tasty: The Art and Science of What We Eat. Just to be confusing, John’s book is really about flavor, more than just taste. In normal conversation, we tend to use taste and flavor interchangeably, but they’re not the same thing.

GRABER: As you might know if you’ve listened to our flavor episode, flavor is much more complex than taste. It’s the whole experience of eating a food, so it includes taste. But it’s much bigger and it’s influenced by many other aspects of a dish.

TWILLEY: As you’ll know if you try to eat with a heavy cold, flavor has a lot more to do with smell than it does with plain old taste. Flavor depends on the aroma chemicals that are sensed in our nose. Also, you should listen to that episode if you haven’t! It’s called Savor Flavor.

GRABER: And if you heard our episode called Crunch, Crackle, and Pop, you’ll also know that all sorts of other things can influence the flavor we experience. Sound is another one. Check out that episode, too.

TWILLEY: Heck, check out our entire back catalog while you’re at it! I say this without any bias: it’s all great. But so taste is just one part of our experience of food. And, on the surface, it seems super simple. I mean, really kind of basic. The general consensus is that there are only five main tastes.

MCQUAID: Bitterness, saltiness, sourness, sweetness, and umami—umami being savoriness.

GRABER: There are other tastes that scientists think we might be detecting, but those are still being argued over. So taste has two primary functions in humans. The first one: it helps us survive. Paul Breslin studies taste at Rutgers University and the Monell Chemical Senses Center.

PAUL BRESLIN: Taste is really a gateway for the entire gastrointestinal tract and is a basis for making the determination whether you should eat it or not eat it. Is it nutritious, is it toxic? Will this help sustain you if you eat it and that it has calories and nutrients and minerals and vitamins, or is it poisonous, and if you eat it you’ll die and that it will end you right there with one meal?

TWILLEY: So it’s important. The second function of taste is kind of like an early warning system for your metabolism.

DANDO: When we take food into our mouths, it’s one of our first encounters with that food. So, to get our body ready to be able to digest it, we can’t just have the food placed right in our stomach. It’s not ready for it. So we have to have the right kind of gastric juices flowing inside of our stomach. We have to have some motility to actually be able to move the food down. Maybe, if we’re eating something very sweet, we’re going to have to have our body prepared for that blood sugar hit with an insulin response.

TWILLEY: Robin told us that your taste receptors will trigger all of these responses depending on what they detect. So your stomach and your pancreas and so on—they’re all gearing up, getting ready for what’s about to hit them.

GRABER: That response happens even if the food never makes it to your stomach—scientists have studied this both in animals and in people. People swish sweet solutions around in their mouths and spit them out. And their bodies get primed for sugar. Your insulin goes up, for instance, even if you just put a piece of candy in your mouth and then spit it out.

TWILLEY: So those are the two functions of taste: the conscious yes or no signal in our mouths, and the unconscious metabolic response. But why these five major tastes? Why did we evolve to detect sweet, salty, sour, bitter, and umami?

MCQUAID: Humans are omnivores so it benefits us to be able to taste as much as we can. Humans have lived in every environment on Earth. This has helped tune our sense of taste this way and that. That whole evolutionary background helps give us the great variety of taste abilities that we have today and also accounts for the great variety of food that we eat and cuisine around the world.

GRABER: John says actually pretty much all of the things our ancestors might have put into their mouths—plants and bugs and other animals—they all contain chemicals that fall within one or more of those five major tastes. But out of all the potential foods we could eat, we have a particularly strong reaction to chemicals that trigger our sweet receptors.

TWILLEY: Sugars, in other words: fructose, glucose, sucrose. Those light up our sweet receptors, and, from there, our brains. And that makes sense. Sugar is one of the most concentrated source of calories there is, and we need calories to live.

MCQUAID: Scientists think that sugar is really a primordial pleasure experience, since sweetness, which is basically the experience of sugar, goes back to the dawn of complex life. So for five hundred million years, life has been responding positively to sugar. So it’s not surprising that humans do also. And really it’s largely out of our control, our reaction to it.

GRABER: Salt is another one—we did an entire episode on salt, which of course you should also go listen to. All mammals need salt to live—we can’t make it, so we need to find sources of it in the environment. Makes sense that we’d be able to taste it.

TWILLEY: And Paul told us salt also triggers a metabolic response, the way the taste of sugar triggers your body to produce insulin. In the case of salt, Paul has managed to show that your blood vessels will actually start relaxing a little if you swish salty water in your mouth, even if you spit it out. Your blood vessels know that to keep your blood pressure constant, you’ll need to pull in more water to counterbalance that incoming salt, and they prepare accordingly.

GRABER: The relationship between salt and blood pressure is actually quite complicated—our episode on salt goes into this in much more depth.

TWILLEY: But sugar and salt are tastes that we crave because they’re things that we need. Sour is a little different. Very sour things don’t taste good, which makes sense because strong acids damage our teeth and tissues. Some people say sourness evolved as a ripeness detector, and so we don’t like really sour things because our body is telling us to hold off and wait until the fruit or berry or whatever is ripe and ready. But Paul pointed out that our response to sour is more complicated than straight up dislike.

BRESLIN: Obviously we like mixtures of acid with with sugar.

GRABER: Like lemonade. But even without sugar, sour flavors can still be appealing.

BRESLIN: People actually do like low levels of sour taste. People will put a twist into a glass of water, a glass of seltzer water.

GRABER: Scientists aren’t quite sure why we like these low-level sour tastes. One theory is that sour points us to vitamin C. Most mammals can make vitamin C, but we humans can’t. So it’s crucial that we be able to detect the ascorbic acid in fruit that gives it that puckery taste. We need that vitamin C. But there are other places we find sourness appealing.

BRESLIN: And in the case of eating virtually anything that’s fermented, whatever that may be, whether it’s dairy being processed into cheese, or cucumbers being processed into pickles, what have you, there’s acid being generated by bacteria. Or, in the case of yeasts, if you’re making wine or beer. And we seem to like that low level of acidity—a little bit of sourness is pleasing to us.

TWILLEY: Our taste for that fermented sour, that could be beneficial in evolutionary terms, too. We all know that our gut microbes appreciate fermented foods. So perhaps our sour taste receptors were guiding us toward that, too.

GRABER: That’s sour, now onto another complicated taste—bitter. And yes, we’ve done an entire episode on bitter as well.

TWILLEY: We really have made a lot of episodes!

GRABER: Which is a good thing. It means we can just tell you all to go listen to them. But bitter’s a weird one. We have more bitter receptors that can taste more bitter compounds, maybe hundreds of compounds, if not more. That’s more than for any other taste.

TWILLEY: Things that taste bitter often contain chemicals that are toxic to us, at least in large doses. Most people in most cultures around the world will not and do not eat anything that’s very strongly bitter. It’s an evolutionary response to avoid poisons. But for foods that are only mildly bitter, it’s a different story. Sometimes we even seek them out.

GRABER: Paul told us that in the real world almost all the food that’s good for us also has low levels of toxins, otherwise known as bitter flavors. We learned to enjoy, maybe even crave, some bitterness so that we can get all the other great nutrients in those bitter plants. And Paul says there’s another evolutionary reason we might like bitter: almost all medicines taste bitter, too. So our ancestors might have developed a taste for self-medicating.

TWILLEY: The fifth and final major taste is umami. And it’s the most recent addition to the canon. A Japanese chemist proposed that umami should join sweet, salty, sour, and bitter back in 1908, but it wasn’t really recognized as a distinct taste with its own unique chemical triggers until 1985.

GRABER: You may have heard of the main chemical trigger for umami that the Japanese scientist had isolated from seaweed broth. It’s called MSG, or monosodium glutamate.

TWILLEY: If you translate umami from Japanese, it means a “pleasant savory taste,” and it’s a really mild taste compared to sugar and salt and bitter. Umami never gets very strong, and we don’t even like it by itself. So why can we taste it?

GRABER: The first thing you need to know is that glutamates primarily come about through a transformation of protein. As protein breaks down, it’s transformed into amino acids and ribonucleotides. And together this is what gives you glutamates.

BRESLIN: Savory taste is about tasting amino acids and ribonucleotides together as a cocktail. So it kind of begs the question then: when are we going to be exposed to pure free amino acids and free ribonucleotides, together at the same time? And really the only time you’re going to experience those is when a food is being broken down, it’s somehow decomposing. And there’s really only three ways that that happens.

TWILLEY: Fermentation, drying, and cooking.

GRABER: You’ll find lots of awesome umami flavors in cooked meats or parmesan cheese, or, yes, seaweed broth.

TWILLEY: And when you taste umami, you’re actually detecting pre-digested protein. Although that doesn’t sound that nice, it’s really good news for your body: you need those amino acids from protein to build cells.

GRABER: Mmm. Delicious pre-digested proteins. But really, all these stories we’ve just told you about why we taste what we taste and why we’ve come to enjoy these tastes—these are just theories. We don’t know exactly what our ancestors were tasting. It’s impossible.

TWILLEY: But you can find some clues for how evolution has shaped taste by looking at other animals and what they can taste. Like, for example, cats. Cats are carnivores, they don’t eat their veggies, and all they have left is an umami receptor.

GRABER: Penguins and dolphins and whales and lots of other sea mammals also have a poor sense of taste—John says they’ve lost a lot of taste receptors over evolutionary time.

MCQUAID: It may be because they’re just swallowing fish whole, so you don’t really have a need to taste them. Most of the taste experience occurs when you’re chewing something. So there’s a lot of that in the animal kingdom, where certain animals, you know, they don’t need to taste something and so it falls into disuse and kind of is evolutionarily filtered out.

TWILLEY: And there’s been plenty of time for that filtering to happen, because the sense of taste is incredibly ancient.

MCQUAID: It goes back to the origin of complex life on Earth. Because once you have complex life, which is more than just single cells floating around, which is multi-celled creatures, they have an inside and outside, and the outside has to detect what is food and what isn’t food. So it goes back at least five hundred million years.

GRABER: And this is why animals that live in the water still have taste receptors in what might seem like strange places. In a lot of fish, taste receptors aren’t just in their mouths.

TWILLEY: Tom Finger is a professor at the University of Colorado School of Medicine who studies taste, and a lot of his work has focused on fish.

TOM FINGER: So the taste molecules are dissolved in the water, and they can swim around and detect taste because the taste molecules are contacting the surface of their skin. So catfish, for instance, have taste buds scattered across their whiskers and the whole body surface.

TWILLEY: It turns outs out that we are more like catfish than you might think. Because we have taste receptors outside of our mouths, too. They show up on a lot of the tissues that interact with these external molecules in our environment. So, in us, the equivalent of catfish whiskers is the lining of your gut.

FINGER: So anything that’s still in your stomach is not really in you. You’re sort of like a giant donut. There’s a hole running all the way through you from mouth to anus and anything inside that is in some sense not really in you. So you have taste receptors throughout your G.I. tract going all the way from your mouth through your intestines.

GRABER: Paul says these likely have an anticipatory role, like the ones in our mouth do. The taste receptors in our digestive system, they also help prime the body for the nutrients that are about to be absorbed into our bloodstream. And that’s not all.

BRESLIN: There are also taste receptors in what I would call regulatory organs or metabolic organs. And that would include the pancreas, the liver, fat tissue, adipocytes themselves, the thyroid, and the brain. And what they’re doing we really don’t know. But it’s a safe bet that in a species like ours that they’re extremely important.

TWILLEY: Back in Colorado, Tom has been working on figuring out what some of these receptors on other parts of our body do. And he says by calling them taste receptors, we’re kind of missing the point.

FINGER: So the taste receptors, actually from the standpoint of biology, you can think of them as just tools and they’re tools for detecting chemicals. So the body can use these tools anywhere. And because we give them the name taste receptors we’re confusing function with the role in biology.

TWILLEY: One of Tom’s projects has been to figure out what the heck taste receptors are doing in our noses.

GRABER: Turns out, these receptors detect chemicals put out by a harmful bacteria in the air that we breathe and then tell our body to mount an immune response. Like in our mouths, the nose taste receptors are just chemical detectors.

TWILLEY: So that’s how taste works, and how it evolved. And now here’s the cool part: as we learn more about taste, we can start to hack it—for fun but maybe also for health.

GRABER: But before we tell you how to mess with your friends’ taste buds at your next dinner party: this week’s sponsors.

(MIDROLL)

TWILLEY: So one of the many intriguing things about taste is that, although it’s one of our oldest senses, it was kind of ignored by science for a long time.

MCQUAID: It’s much easier to study the detection of light for example or sound, because these are sort of shared experiences, whereas an experience of taste or or smell also which are both components of flavor is a subjective experience. And so basically once science tried to wrap its arms around this it failed. And so a lot of scientists kind of gave up.

GRABER: And it’s not just that it’s hard to study. We also ignored taste because scientists and philosophers have looked down on it—for thousands of years. John says the ancient Greeks considered it the lowest and grossest of the senses.

MCQUAID: There’s a historical tradition in Western culture that makes taste and smell, particularly taste, second-class senses because they’re tied to eating, which is a kind of a base activity, you know, devouring stuff, putting stuff in your mouth, chewing it. You know, it’s what animals do. And, of course, we’re animals. But it wasn’t considered a higher sense.

TWILLEY: Still, throughout history people had theories—about how many tastes there were, and how the tongue detected them. But until really quite recently most of what we knew about taste was… wrong.

GRABER: The most enduring myth of the past century—and it’s one that you might even have learned when you were a kid—it’s a myth known as the tongue map. And we can lay the blame for this mistake at the feet of Edwin G Boring.

MCQUAID: He was an influential twentieth-century psychologist.

TWILLEY: And he decided to write the definitive book on the history of the senses—a big tome. And while Mr. Boring was researching the taste section of his book…

MCQUAID: He came across this study that had been done—this was I think in the 40s, he was writing this—and he came across a study that had been done about 30 years earlier by a German scientist that looked at the sensitivity of the tongue to different tastes. And this study showed that depending on where you were on the tongue, the sensitivity to these tastes differed, sometimes by a little, sometimes a little bit more.

GRABER: You know, like, one part of the tongue was more sensitive to sweetness. Another part was slightly more sensitive to salt. The German scientist published his data in the early 1900s. And then decades later, Boring drew on that data to draw his graph.

MCQUAID: But it was an exaggeration: the original data, you know, there were very limited differences. And suddenly now there were huge differences in this graph.

TWILLEY: Because Boring was so influential, this tongue map idea spread through the scientific community.

MCQUAID: And then pretty soon that morphed into maps of the tongue that showed clearly demarcated areas, you know, like on a geographical map where there’s a border, a clear border. It’s like the tip of the tongue tastes sweet and the back is bitter.

GRABER: Soon, these maps swept popular culture as well.

MCQUAID: They appeared in textbooks and they were used in children’s scientific experiments in elementary schools and it kind of became the conventional wisdom that different parts of the tongue were anatomically devoted to different tastes.

GRABER: So Boring was totally wrong. But scientists didn’t figure out just how the tongue works, how the taste receptors work, until quite recently. And that’s because of a much better understanding of genetics.

TWILLEY: Back in 2000, John actually visited scientists at the NIH when they were first isolating taste genes.

MCQUAID: Essentially they were looking for a needle in a haystack.

GRABER: They knew what taste receptors were, and they knew that there were genes to express them, but they didn’t know how to match the two.

MCQUAID: And basically through kind of a sieve like process they managed to isolate a sweetness receptor and match it with its DNA code in the genome.

TWILLEY: The scientists were working with rats, but fortunately, the human gene and receptor for sweetness is pretty similar.

MCQUAID: So once they had that, finding the human version of it was quite easy. And once you have that you can begin to experiment. You can make copies of sweetness receptors yourself, put them in a petri dish, and see how they react to different substances: to sugar, to artificial sweeteners, et cetera, et cetera.

TWILLEY: And from there, you can begin to understand how the sensation of taste is triggered, how it’s sent to the brain, and, ultimately, how we perceive it.

GRABER: One thing scientists have figured out is that, as we said, Boring was wrong. Every taste bud on our tongue has multiple receptors and those pick up many different tastes. It is absolutely not true that one section of the tongue is dedicated to sweet. There may be very slight differences in sensitivity, but everything is being sensed everywhere.

TWILLEY: But we’re not all sensing it exactly the same. There are pretty significant individual differences. And where they come from—that’s something that Linda Bartoshuk has been trying to get a handle on for decades. She’s a professor at the University of Florida and kind of a legend in the taste world.

LINDA BARTOSHUK: Well, it all started when we were doing work in New Haven, Connecticut, and we were working on—the first genetic known taste was to something called PTC. It was a bitter compound and it was known since the 1930s that some people couldn’t taste it. So I was working on that problem, and we decided that the methods that had been used on the problem up to then were very old-fashioned and we were going to do something more modern. We were going to actually see how bitter this compound was, not just whether you could taste it or not, but how bitter it was. Well, it turns out the variation was simply enormous. And some of the people got such incredibly intense bitter taste from this, that we started calling them supertasters.

GRABER: Yes, Linda is the one who coined the term supertasters. A lot of listeners have asked us to do an episode on supertasters.

BARTOSHUK: Supertasters are people who experience particularly intense taste sensations, the most intense taste sensations that are experienced by any people. Those are supertasters.

TWILLEY: Once Linda and her colleagues identified this group and started studying them, they quickly realized that it’s not just bitter PTC that supertasters taste more intensely—its everything.

BARTOSHUK: Yes, it is. Sweet is more intense to supertasters by about a factor of two or three.

GRABER: There is actually a continuum—it’s not a yes or no, super taster or not. Linda herself is in the “not” category, she’s on the non-tasting end of the taste spectrum. But a lot of people fall somewhere in the middle.

TWILLEY: Most scientists estimate that roughly a quarter of us are what they call nontasters, about a quarter are supertasters, and the rest are sort of medium.

BARTOSHUK: Part of it has to do with how many taste buds you have. Taste buds are on the human tongue in structures called papillae. And fungiform papillae, the ones on the front of the tongue, if you—under magnification they look like little button mushrooms on your tongue. And supertasters have many many more of these than people like me do.

GRABER: We decided to test some of these things out when we were on tour with Pop-Up Magazine. First, we wanted to find out who could taste PTC. We got a whole group of people in a backroom in one of the theaters and told them to put a piece of paper on their tongue.

GRABER: Why are you nervous?

KELLEY CARTER: Because I don’t really know what I said yes to at this point, so I don’t know what’s about to go down.

TWILLEY: It’s definitely not drugs.

CARTER: I’m a role model so I hope it’s not like drugs or anything.

TWILLEY: I don’t know if it was peer pressure or what, but they all did it. They put these slips of paper on their tongues without even knowing what it was.

CARTER: Just put it on the tongue.

GRABER: Yep.

TWILLEY: Paper for me.

GRABER: Really? I totally taste it.

DOUG MCGRAY: Tastes really terrible. It’s bitter, it’s really bitter.

CARTER: Paper for me.

GRABER: Paper for you too.

CARTER: Yeah.

GEOFF MANAUGH: I have a very, very bitter taste in my mouth—it tastes like aspirin or something. Yeah, it’s bitter for me too.

GRABER: It tastes exactly like aspirin. I totally agree. Oh Tim, you look like you’re in pain.

TIM BUNTEL: Yeah, it’s dreadful.

TWILLEY: In our little group we had four bitter tasters: Cynthia, Tim, Geoff, and Pop-Up boss Doug McGrey. I had a little bit of a bitter aftertaste, but not enough to scrunch up my face like those guys.

GRABER: One of our fellow contributors, Kelley Carter—she didn’t taste anything. Neither did another couple of the Pop-Up crew, Tina Antolini and Anita Badejo. No bitterness. Just paper.

TWILLEY: You can try this at home—I ordered the PTC paper off Amazon. It was kind of amazing how different all our reactions were.

GRABER: So not everybody who tastes PTC—who tastes that bitter—is automatically a supertaster. But Linda says it’s the first step. You have to be able to taste it. But then supertasters taste it super intensely.

BARTOSHUK: Supertasting is much more than this initial bitter compound we first discovered, it happens to all taste. But is there some biological utility that made—were supertasters the originals, and there was a mutation that made the rest of us? I don’t know. Very interesting question. But my picture of this, I think about the Neanderthals wandering around. Or maybe the first humans of our type wandering around. And, by the way, women are more likely to be supertasters than are men, and that gives you a clue. So maybe when they moved into new territory the chief sent his wife out to check out the local plants and if she didn’t die, they were OK. And she didn’t die, they were safe. But you’d want to supertaster to do that because the supertaster would taste the bitter more intensely and bitter is a signal for poison.

TWILLEY: This ability to taste PTC—it’s really interesting. It evolved independently in humans and, in our closest relatives, chimps. That implies that having some of your population as bitter tasters has an evolutionary advantage for the species as a whole. Otherwise it wouldn’t persist in humans over time like this, and it wouldn’t pop up separately in other species.

GRABER: Tasting PTC or not seems to be largely governed by one gene. Being a supertaster is more complex—Linda suspects multiple different genes contribute, although she hasn’t identified them yet. But there are patterns in the population as to who is likely to be a supertaster or a non taster.

BARTOSHUK: For example, Caucasians have the fewest supertasters. And men have fewer supertasters than women, and this led one of my post-docs one to say white men can’t taste. But I told her she couldn’t say that because it’s politically incorrect.

GRABER: What’s funny is that all three of the white guys backstage at Pop-Up could taste bitter—and remember, that’s the first step towards being a supertaster. But the two African-American women couldn’t.

TWILLEY: While our group was awesome, it wasn’t exactly statistically significant. But so PTC strips are the first step. The next step in diagnosing whether you are a supertaster or not is to count your taste buds. This involves dying your tongue blue. Funnily enough, our Pop-Up buddies didn’t want to do that before the show. I don’t blame them—I made Geoff dump a teaspoonful of blue food coloring on his tongue and he looked really funny.

GRABER: I think maybe you gave him a little much.

TWILLEY: Yeah, I think maybe we maybe overdid it a little.

GRABER: At least you overdid it on Geoff.

TWILLEY: It was a test run. That’s what husbands are for.

GRABER: Of course, we didn’t read the instructions—there are instructions for this experiment online—we thought you just squeezed out some dye on your tongue and then looked to see what stuck and what didn’t, because blue dye doesn’t stick to taste buds. But it’s a little more complicated than that, so after Geoff spent many minutes swishing out blue water, we decided to tackle this more scientifically back at home. We found instructions at Scientific American—we’ll link to it on our website.

TWILLEY: So it turns out we’re both basically average. At least when it comes to this. And actually, this is not a bad thing.

BARTOSHUK: Now, supertasters are going to be a little bit fussier than other people, because they’re going to notice bitter whenever it’s present. And there are going to be foods they don’t like, like leafy green vegetables that tend to be bitter. So there’d be perhaps an advantage to non-tasting if you’re in an environment with a lot of bitter compounds that are safe. But what if you’re in an environment with a lot of bitter compounds that are dangerous? Now the supertaster has the advantage.

GRABER: Supertasters generally don’t eat as many vegetables, so they seem to be at a higher risk for colon cancer. But they also tend not to drink and smoke as much, so they apparently are at lower risk for head and neck cancer.

TWILLEY: Swings and roundabouts. But all you supertasters out there, you can stop patting yourselves on the back.

BARTOSHUK: In some sense it was a poor choice of name because super implies something special, great. I’m delighted that I am not a supertaster. It just means more intense. And the truth is, I look around at extreme supertasters and I don’t think they’re having as much fun with food as I am. Let me qualify that one step. We have looked at the pleasure that supertasters and others get from food. And if you look at the favorite food of a supertaster—they really love it. And you look at something they don’t like, they absolutely hate it. So the supertaster experience is a much larger hedonic range of extremes to like and dislike. I’m sort of more in the middle. I like a lot of things but not terribly much. The supertaster may like fewer. But the ones he or she likes, they get tremendous pleasure from. Now that’s interesting. For example, chefs tend to be supertasters. More of them than you’d expect by chance. Is this that has something to do with the pleasure they get from their favorite foods? We don’t know. I’d like to see somebody study that who knows cuisine more than I do.

TWILLEY: This phenomenon of supertasters getting more pleasure from their favorite food—given how central food is to our pleasure circuits overall, this has really interesting implications, beyond food

BARTOSHUK: I mean are supertasters kind of a different group? Are they hedonically more volatile? Do they get more pleasure from a lot of things? That’s a real possibility. We just don’t know yet.

GRABER: This question of pleasure is a really complicated one—whether or not you’re a supertaster is only one factor in whether or not you’re deeply enjoying your meal. For example, research Linda’s done shows that overweight people get more pleasure from their food than thin people.

TWILLEY: And that’s complicated too. Because that brings us to the connection between our sense of taste and obesity. We live in a world where sugar is everywhere but we’re built to love sweet so intensely.

MCQUAID: The signal from sugar is, you know, give me more sugar.

TWILLEY: And that was totally fine back when we encountered sugar very, very rarely—in fresh berries, maybe, if we were lucky in wild honey. Now, of course, we have sugar at our fingertips day and night. Robin Dando—he’s the food scientist at Cornell—he’s been studying the connection between taste and obesity for a few years now.

DANDO: It’s a cruel joke really that we’ve been put together to just go after things like sweet and fat and to really like them. We’re programmed to want this in high quantities, we’re programmed to kind of put on weight for the hard winter that might be coming. Because that evolutionarily that means that we might stick around for longer. So it’s kind of a cruel joke now that this isn’t really a problem anymore, but we’re still programmed the same.

GRABER: Robin’s been studying the sense of taste in mice. One thing Robin’s found is that as the mice become obese, they lose tastebuds. And he thinks there’s a connection.

DANDO: Now, a couple of caveats in there of course. One is that these are mice, these aren’t humans. But, as I say, it’s a strong indicator. And then two is: Does losing a handful of taste buds actually do enough to change a person’s eating habits? Again, we don’t know that for sure. We’re looking into both of those questions right now.

TWILLEY: So we don’t know for sure, but you can easily imagine that if somebody has fewer taste buds, they might be getting less sensation from their food.

DANDO: So if that level of reward is decreased, then there are a couple of obvious things you could do to combat that. One is you could just eat more. And the other is you can eat more intensely tasting stimuli, so more intensely tasting usually is going to mean higher calories. So if that’s the case then, that when somebody starts to put on weight they lose tastebuds, they are driven to consume more, then that means that they’re going to put on more weight, lose more taste buds, and be driven to consume more again. So it’s kind of a dangerous positive feedback loop that we think could have something to do with the obesity epidemic that we’re living in right now.

GRABER: Supporting his hypothesis that gaining weight reduces taste sensation, and that losing weight might bring it back, Robin says there’s some evidence that people who lose weight quickly after gastric bypass surgery are more sensitive to taste afterwards.

TWILLEY: He’s also found that there are hormone receptors in your taste buds, too. They’re picking up on circulating hormones like leptin, which signals us to feel full. Those hormone levels change in obese people too. So that could also be affecting their experience of taste.

GRABER: And so maybe in there future there’ll be a way to use these taste-related phenomena to help people lose weight.

DANDO: So there are a lot of issues that happen with the body when someone becomes obese. And this would only be one of them. But if there is a portion of the process of becoming obese that could be attributed to the taste buds, then we’d really be interested in trying to kind of put that right, to kind of hack the taste bud to make it do things that we want people to do in terms of food choice, then I think that’s a really exciting idea.

TWILLEY: This is all just speculation right now—we don’t know enough to start hacking our taste buds to try to reverse obesity. But we do know that our sense of taste can be manipulated and changed, for all sorts of reasons.

GRABER: Like take pregnant women. All of a sudden things that used to taste good are suddenly disgusting. They throw up more frequently. Basically, their hormonal changes are making them more sensitive to potential toxins, more sensitive to bitter flavors. Children are the same, they’re really sensitive to bitter when they’re young. These are two super vulnerable groups, so it makes sense from an evolutionary perspective that they’d reject bitter and potentially poisonous foods.

TWILLEY: What you eat—your culture, your memory associations—that has a really strong impact on your sense of taste, too. John told us about a group of indigenous Peruvians who are all PTC bitter tasters. But where they live, one of the staple foods that they rely on is this really, really bitter potato relative. And so they seem to have reset their bitter taste perception—lowered it to the point where they can all eat and enjoy this potato, even though their genes would seem to indicate otherwise.

GRABER: So even if you are genetically sensitive to PTC, it doesn’t mean you can’t learn to enjoy bitter flavors. I taste PTC pretty strongly and I love bitter. Other tastes can be reset, too—we humans are really malleable. Robin told us about research showing that if you start eating food with less salt or less sugar in it, you become more sensitive to salty and sweet foods.

TWILLEY: There’s even some evidence that your mood affects how things taste. Robin has been working on this, too.

DANDO: So our model was we set up a stand at the hockey game at Cornell. If you’re interested in sports and going to Cornell then you’re probably going to the men’s hockey game.

GRABER: He found that enthusiastic fans whose team won, their food tasted better. But if the team lost, there went that delicious hot chocolate. Not so delicious anymore.

TWILLEY: And this makes sense, because there are those hormone receptors in the taste bud. And one of the hormones they pick up on is serotonin. Serotonin levels are connected to happiness versus depression. So there’s lots of interesting new science happening here too.

DANDO: There is a group that looked at SSRIs, so these are selective serotonin re-uptake inhibitors. So probably around about the most prescribed type of antidepressant in the country. And found that indeed people do start to perceive tastes, particularly sweet taste, as being different when they have have a lot of these antidepressants inside their body.

GRABER: All of this—mood and antidepressant research, the taste bud sensitivity and obesity research—all of this might help scientists hack our taste buds in the future to improve our health. But there are some fun ways to hack our taste buds today. Nicky had the chance to try something that I’m super curious about.

TWILLEY: It was when I was over in London.

EMMA ZHANG: Hi. My name is Emma Zhang. And we are at the Mixed Reality Lab in City University London. So we have this device over here which is a small device which you can put in your mouth and you will feel a virtual taste sensation.

TWILLEY: Basically there are two silvery plates hooked up to a set of wires. And you put the tip of your tongue in between them. Which I did. And then Emma electrocuted my tongue.

TWILLEY: Right, here goes. Oooh! Ahhh!

ZHANG: Yeah.

TWILLEY: Oh my god. That was ridiculous. Can I do it again?

TWILLEY: The taste she sent me was super sour. This is how it works.

ZHANG: So, for example, when we put something on our tongue, the chemicals will translate into electrical signal in our brain, and what we are doing here is to reproduce those electrical signals. So you will feel the same taste as if you are biting a lemon.

TWILLEY: The idea that Emma and her colleagues have is that you could build this kind of digital taste into cutlery, so your ice cream, say, would taste sweeter on an electric spoon. I don’t really know that I would sign up for getting my tongue electrocuted on a regular basis though.

GRABER: Doesn’t sounds like so much fun to me either, but I’d love to try it once. Some day. There’s another way to trick your taste buds. We used a pill—it’s an extract from a tropical African fruit called a miracle berry. What you do is you take the pill and slowly let it dissolve and coat your tongue. We handed them out to everyone in the dressing room. Then we handed them slices of lemons and limes.

DOUG MCGRAY: My new favorite food is lemon and pills.

TWILLEY: I could eat this whole lemon. Why didn’t we get more lemons?

GRABER: Oh my God, this lime is amazing.

TWILLEY: Everyone was just sticking whole chunks of lemon and lime into their mouths like they were apple slices. Then we moved on to something that’s already pretty sweet: strawberries.

TINA ANTOLINI: This is my worst nightmare. Everything is sweet.

MCGRAY: Intensely sweet.

GRABER: Oh my God, it’s way too sweet for me.

MCGRAY: Too much candy.

GRABER: Like it’s been dipped in sugar.

TWILLEY: It’s kind of disgusting.

GRABER: It’s a strange day when strawberries are so sweet that we’re calling them disgusting. So Linda says scientists don’t know exactly how miracle berries work, but here’s the leading theory: there’s a protein in the fruit that has sugar molecules on it. The protein attaches to your tongue with the sugar just out of reach. Then if you eat something acidic, like a lemon, your taste buds pucker, and they access the sugar molecules, too. So the lemon now tastes like it’s been coated with sugar.

TWILLEY: We didn’t stop at fruit, though. We tried beer and olives and blue cheese too. The olives—which, I love olives—they were just pure salt. Completely inedible. And the blue cheese was too salty and not funky and a little bit sweet.

GRABER: So that means that the scientific theory maybe doesn’t quite explain it all, because if it’s a protein with a sugar molecule attached, why would bitter and salt get so much more intense? Mysteries left to solve.

TWILLEY: This is another one you can easily try at home: we have a link to buy miracle berry pills on our website. Just be aware that if you go out for lunch afterward, like I did, your sandwich will taste disgusting.

GRABER: Linda says the effect lasts from about 15 minutes to about an hour and a half, depending on how strong your saliva is.

TWILLEY: So hacking your taste buds is possible. It works. But can we use it to achieve our health goals?

GRABER: There’s some evidence that this doesn’t work as intended. One way many of us hack our taste buds on a regular basis already is by consuming artificial sweeteners: these are non-sugar chemicals that trigger our sweet taste receptor, but our bodies don’t get any calories from them. Scientists have been showing that replacing sugar with artificial sweeteners isn’t helping people lose weight. In fact, with artificial sweeteners, people might actually be eating more. Maybe because our body is primed for sugar but we’re not getting those calories—and that triggers a whole set of reactions.

BARTOSHUK: You know and we should pay more attention to that. And by the way, that could be true of everything we do. For example, when you make acid stay sweet with miracle fruit the body’s expecting sugar. If we were really eating a lot of it, would that have consequences? It probably would. We ought to keep an open mind about that. Because when we come up with these things, it’s not nice to trick Mother Nature. She sometimes has her ways of getting even. And it’s very, very important to try to think of how things could go wrong. That’s our job as scientists.

TWILLEY: So we need to be careful. But this uncertainty—this is what makes the science of taste really exciting. It’s still such an open field. Robin told us that scientists are still trying to figure out exactly how sour works, for example. And there are lots of scientists trying to show that we have more than five basic tastes.

GRABER: We’ll write about that in our sustaining supporters email—that’s for folks who give $5 an episode or $9 a month. You can sign up at Patreon or on our website. In any case, there is a lot more still to learn about taste.

TWILLEY: It’s funny—taste is one of the oldest tools we have to make sense of the world, and one of the least well understood.

(MUSIC)

(POST-ROLL)

TWILLEY: Thanks this episode to all the people we spoke with: John McQuaid, Linda Bartoshuk, Paul Breslin, Robin Dando, Tom Finger, Emma Zhang —we have links to their books and research on our website.

GRABER: And a huge thanks to our partners Tim and Geoff and our friends and colleagues who were on tour with us with Pop-Up Magazine. The backstage taste hacking was ridiculously fun, and you all were great sports.

TWILLEY: We’ll be back with a new season in four weeks. In the meantime, catch us on tour: our Boston Museum of Science show is sold out, but the Michigan State University Science Festival performance is first come, first served, no tickets necessary. See you there!