TRANSCRIPT So Hot Right Now: Why We Love the Chile Pepper

This is a transcript of the Gastropod episode, So Hot Right Now: Why We Love the Chile Pepper, first released on April 27, 2021. It is provided as a courtesy and may contain errors.


CYNTHIA GRABER: LAUGHTER. This is you on Carolina Reaper pepper, huh?

TWILLEY: I know, it just keeps COUGH

GRABER: It keeps giving and giving.

TWILLEY: I was just like: Oh, no. LAUGHTER. Anyway, I was just like, can you imagine if I rubbed my eye? I’d be in the emergency room. Oh dear. Anyway, kids, don’t try Carolina Reaper at home.

GRABER: Do not. Do not even open the jar.

TWILLEY: Yeah, do not even have a friend ship you the jar.

GRABER: I promise, I was not trying to unleash a chemical bomb on Nicky and her husband Geoff. The lid to the jar of Carolina Reaper chile powder apparently came off in the mail! She was coughing throughout our entire next recording session.

TWILLEY: I’m this close to reporting you to HR, Cynthia. Except that we don’t actually have HR at our two-woman show. But really. However mad I sometimes make you, that was not acceptable behavior in the workplace.

GRABER: I do still feel bad about it. I mean, the guy who sold me all the chiles we bought for this episode, INCLUDING the Carolina Reaper, he told me we have to be so very careful with it; he was in pain for 20 minutes just from pouring it into jars for sale, from inhaling the dust!

TWILLEY: I do literally know how he feels. Sadly.

GRABER: Yes, this episode, we are deliberating subjecting ourselves to the chile pepper burn—

TWILLEY: —and not just any chile pepper burn, but the hottest pepper in the world.

GRABER: That’s what we do for you dear listeners. We of course are Gastropod, the podcast that looks at food through the lens of science and history, I’m Cynthia Graber—

TWILLEY: And I’m Nicola Twilley, and, normally, I really like chile peppers. I have lots of different dried ones in my spice cabinet and all kinds of fun fermented hot sauces and chile crisp and salsa macha in my fridge. So I was looking forward to this episode.

GRABER: Unsurprisingly, I have pretty much the same setup in my kitchen as Nicky does—I have hot sauce on the table for nearly every meal, including breakfast! But I started to get a little nervous hearing her cough. Which made me wonder—why do we humans love something that sometimes feels like it’s trying to kill us?

TWILLEY: The chile is botanically a berry, for heaven’s sake! Why is it so hot and spicy, rather than just sweet and fruity?

GRABER: How did this rather assertive berry spread from its home in South America and conquer, well, almost the entire world?

TWILLEY: To the point where I can’t even imagine Indian or Chinese or Nigerian food without it.

GRABER: And why was the U.S. and northern Europe so slow to catch on?

TWILLEY: All that plus the rise of the super hots—is there a limit? Or will chiles finally actually kill us?

GRABER: This episode was made possible thanks to generous support from the Alfred P. Sloan Foundation for the Public Understanding of Science, Technology, and Economics, as well as the Burroughs Wellcome Fund for our coverage of biomedical research.

GRABER: This might sound like a just-so story, but: Why is the chile pepper hot?

TWILLEY: To answer that, we spoke to Maricel Presilla. She is a chef and a culinary historian and she wrote an incredibly beautiful book called Peppers of the Americas, which traces chile peppers all the way back to their South American origins.

MARISEL PRESILLA: So the forebears of today’s peppers and tomatoes split off from a common ancestor about 20 million years ago in South America.

GRABER: Maricel says that back then, millions of years ago, peppers looked and smelled like a tasty snack to the animals in the region.

TWILLEY: Which was a problem because the chile peppers precious seeds would get destroyed in most animal guts. And chile peppers want to have baby chile peppers.

GRABER: And so chiles developed a defense strategy.

PRESILLA: A devilish, you know, non-poisonous thing in the form of capsaicin, which is an alkaloid, so it’s painful to most animals’ taste buds, and they avoided them, but birds didn’t.

DANISE COON: Birds have this amazing ability to not feel the heat sensation because they don’t have the same heat receptors in their mouths or their skin the way we do.

TWILLEY: Joining the chile chorus is Danise Coon. She’s a chile pepper researcher at New Mexico State University, home to the one and only Chile Pepper Institute.

COON: And so they can eat lots and lots of these tiny hot little berries and pass it through their digestive system unharmed and it grows into a new plant, whereas us mammals, we can feel the heat and it passes through our digestive system and actually our system destroys the seeds so it can’t grow into a new plant. And that’s kind of why we think that the chile pepper plant evolved capsaicin, was to keep mammals from eating them, but then look at what we go and do.

GRABER: Danise told us chile peppers are the only plants in the world that produce capsaicin. And because chiles are making capsaicin to protect their precious seeds, they put most of that protection right around those seeds.

HAROLD MCGEE: And if you cut pepper open, even if it’s a bell pepper with no capsaicin at all, you notice that the seeds on the inside are attached to a white tissue, which the botanists call placenta because it supports the developing embryo as it develops. And it turns out that most of the capsaicin in chile plants is found in that supporting material in the placenta.

TWILLEY: Listen up, this is Harold McGee, star of our recent smoke episode, author of Nose Dive and On Food and Cooking, and all round food science whiz kid. And he is correcting a common misperception—a lot of people think that most of the heat in a chile pepper is in the seeds, but he says no. It’s mostly in the white placenta stuff

MCGEE: The thing that happens, though, is that if there is a lot in the placentas, during the drying process, as the fruit shrinks, it’s easier for the capsaicin in the placenta to spread around the interior of the fruit. And so it’s much more difficult to kind of pick out the placenta and minimize the heat once the chiles have been dried.

GRABER: So this is why and where chiles are spicy. But if the point was to put us off from eating them, why did early humans in what’s now Peru and Bolivia give them a try?

PRESILLA: Prehistoric hunter gatherers must have been curious about these beautiful scarlet pods. And they experimented with the specimens that they found close to their own settlements.

TWILLEY: Some of these wild peppers would have been more spicy and some less—different plants and even different fruits on the same plant can have more or less capsaicin.

GRABER: But there’s one particular reason that ancient hunters might have preferred the spicy ones—capsaicin naturally repels insects. But sometimes those insects might mistakenly take a bite of a pepper. But even with insect bite holes in them, the damaged berries wouldn’t have gone bad. And that’s because capsaicin also fights off fungus.

TWILLEY: A fungus-free pepper will last longer, which is great for a human that wants to eat it, and the capsaicin in it might even prevent other food from going moldy. That’s even better. The researchers who discovered this connection between insect bites and capsaicin levels, their theory is that humans might have deliberately sought out and added the spiciest peppers to their foods as a kind of early preservative. Kind of like garlic.

GRABER: And Maricel thinks there was another reason that early humans in South America were so attracted to peppers. She visited the archaeologists’ site where some of the very earliest pepper seeds from food were found, and she saw villagers who live nearby the site preparing food from corn, root vegetables, shellfish—and not much else.

PRESILLA: So it struck me that what elevated, you know, this type of cooking from subsistence rations to a true cuisine was the skilled use of peppers. So the local ajíes that I had seen women crushing into sauces.

TWILLEY: These chile peppers—they’re called ají locally—Maricel says they’re doing two different things. They make bland starchy food more interesting, for sure—more flavorful and spicy. And the irritation of the capsaicin—that stimulates your mouth to produce more saliva, and saliva contains an enzyme that breaks down starchy foods. So chiles make starchy foods less boring to eat, and easier to digest.

GRABER: Honestly, that pep from the heat in addition to all the great flavors in chiles, that spice can kind of make food more exciting. It really does add some literal zing.

TWILLEY: I mean, how many terrible sandwiches and on-the-road breakfasts have you rescued with some hot sauce? All of them.

GRABER: All of this explains why we might have been attracted to peppers. But it’s been hard for scientists to figure out how long we’ve been eating spicy peppers. Mostly that’s because in the hot, humid regions where many of the earliest peppers grew, the seeds and all the rest of the plant disintegrate really quickly. Which made one site in Peru really exciting.

PRESILLA: The site is called El Brujo, the shaman. And it has been occupied continuously for as long as we have evidence of human beings in western South America. So you find temples and subterranean dwellings, burial chambers, the remnants of successive civilizations. But to me, one of the most important sites in the complex is a huge, a dark color mound called Huaca Prieta.

TWILLEY: Maricel told us that Huaca Prieta was first excavated in 1946 by an archaeologist from the American Museum of Natural History.

PRESILLA: And they started excavating this mound, they found, you know, dwellings and kitchens, they found ancient garbage dumps and latrines in the stages of their exploration, so they were peeling layer by layer of history. But the refuse heap was actually much more exciting to them than any, you know, jewels, because organic matter is very difficult to come by.

GRABER: But there was plenty of it at Huaca Prieta—so the archaeologists took samples of the fossilized poop. They had it analyzed using the new technique at the time of carbon-14 dating to get a better read on how old it was—but even more exciting, they sent that poop to a guy who founded an entire new field of research that uses ancient poop to figure out what ancient people ate.

TWILLEY: And this guy concluded that seven and a half thousand years ago, the people who lived at this site were eating not just one but a few different kinds of spicy peppers.

GRABER: Probably then and still today, there are around 30 species of wild peppers. At some time around the time the El Brujo people were eating chiles, or since then, nobody really knows, we domesticated five species that we still enjoy today.

PRESILLA: Now, the most important of these species is Capsicum annuum, which is believed to have been domesticated in what is today Mexico. So these five species basically have their niches historically, there were places where they were domesticated first.

TWILLEY: Maricel compares the five domesticated chile pepper species to the five alliums—garlic, chives, onions, leeks, and shallots—in terms of how different they can be in their flavor personalities.

GRABER: Annuum is the most common domesticated chile and so unsurprisingly it’s the most diverse—basically all the dozens of peppers you might eat in Mexico are annuums: jalapeños, poblanos, bell peppers, all annuum.

TWILLEY: Then there’s chinense, of which the most famous is probably habanero. Number 3 is baccatum, which you mostly find in Peru, and then there’s number 4, frutescens, which Maricel says is the most one-note of the chile pepper family—it’s just kind of sharp and hot. The most famous frutescens is Tabasco.

GRABER: The fifth and final species is called pubescens, and this one we almost never eat in the U.S. or Europe because it doesn’t dry well, and so mostly people eat it fresh in South America, or it gets shipped frozen and you might find it under the name rocoto or locoto in Latin American restaurants.

TWILLEY: All of the five have different heat profiles and different flavor notes as a species, and then there’s obviously a huge amount of variety within the species and, really, we just needed to try them.

GRABER: We had eight different dried chile peppers lined up in front of us—it wasn’t the season for fresh. We decided to start with the tepin—it’s an annuum, it’s  a tiny little round pepper, like the size of a little wild blueberry. It’s the one you can buy in the stores that’s closest to the wild chile pepper. And because it was dried, we had to rehydrate a few with boiling water.


GRABER: So shall we try one?


GRABER: Okay, here we go.

TWILLEY: Here we go.

GRABER: Oh, my God. Oh my God, why did we start with this? Oh, my God, Nicky. LAUGHTER Why? WHY. Why! I had to just swallow it. Why! I think my digestive tract is burning. COUGHING

TWILLEY: Okay, so Cynthia. I think it’s good. Now I feel like really pretty good about having had the reaper yesterday. Because obviously, this is nothing. This is NOTHING. Yes, it’s spicy.

GRABER: Oh my god, it’s spicy. And it COUGH has some, it has some nice flavors to it.

TWILLEY: But it’s smoky.

GRABER: It has some smokiness, it has some fruitiness. COUGHING.

TWILLEY: It’s quite sharp. It’s quite sharp.

GRABER: I swallowed that really quickly. I couldn’t let it spend too much time in my mouth.

TWILLEY: I was trying to let it spend time in my mouth. And now… WHISPERING I feel like that might have been a mistake.

TWILLEY: So obviously we were in a fair amount of pain. And like we said, that pain is the plant trying to get us not to eat it, so that a bird will eat it instead.

MCGEE: The most obvious effect of capsaicin on the body is the pain. And it turns out that, you know, we call the sensation that capsaicin causes “heat.” And that’s for a very good reason because it turns out to activate a receptor in our body that responds to what’s called noxious heat: Heat that’s above a temperature that our bodies should be encountering.

GRABER: The capsaicin molecule is triggering a receptor in our mouths—and maybe in my esophagus—that has a lot of other work to do. It’s the same receptor that would be kicked into high gear if you put some boiling hot coffee or tea in your mouth. It’s part of something called the somatosensory system.

PAM DALTON: It’s our danger sense. If people are born with—and it’s a rare condition—but if they’re born without the ability to detect somatosensation, they experience many different kinds of injuries, sometimes fatal ones, because they simply have no ability to sense pain.

TWILLEY: Pam Dalton will be familiar to those of you who came and saw us in person in Philadelphia, at our live show at the Franklin Institute. She is a scientist at the Monell Center in Philly and she works with capsaicin in the lab.

GRABER: Pam told us that we can in fact feel capsaicin anywhere on our body, as long as our skin isn’t too tough—

DALTON: But it’s especially sensitive to the mucosa. And in the oral cavity, we have a lot of receptors that are sensitive, that are essentially the receptors for the capsaicin molecule. And so it’s a very sensitive place to actually experience it.

TWILLEY: No kidding.

GRABER: Another thing I noticed personally—after I ate that tepin, it felt like the very follicles on my head were starting to sweat. I was literally hot. Which is a weird reaction, because the temperature in the room hadn’t changed at all.

MCGEE: That’s because our body thinks it’s hotter than it actually is. And so it’s putting into effect all these cooling mechanisms so that it can maintain our temperature appropriately. But our temperature hasn’t changed. So that’s the interesting thing.

TWILLEY: It’s really weird. A good dose of capsaicin triggers all the same responses in your body as if you were literally getting a third degree burn, EXCEPT the actual tissue damage of a third degree burn. You sweat, you get flushed, your blood vessels dilate—your tongue literally turns redder when you eat spicy foods, all its blood vessels dilate to try to cool things down.

GRABER: This whole process is weird, yes. But it’s also kind of useful in parts of the world where you might want to sweat, even while you’re sitting around eating.

DALTON: And this is one of the reasons—and of course it’s borne out by sort of anthropological data—but this is why hot, spicy foods containing capsaicin have been used a lot in very tropical, warm environments as a way to promote cooling of the body and reducing the body heat by this evaporative cooling that occurs.

TWILLEY: Meanwhile, back in nontropical Philly, Pam actually works with neat capsaicin in the lab.

DALTON: It’s white and a little crystally. Powdery but a little flaky too, as well.

GRABER: After that tepin, the powdered pure capsaicin sounds a little terrifying to me. We wondered if Pam ever tried it neat.

DALTON: Of course! LAUGHS I’m one of those scientists that likes to put things in my nose and in my mouth, you know, depending on what I’m doing. But mostly we have used it in solutions. And once we were doing it in aerosol forms, so we had an aerosol generator and we were using that. That was a little dangerous because you would walk into a room where it had been aerosolized and it was completely invisible. But it would essentially cause reflex apnea. It would take your breath away. You would almost stop breathing as a reflex. Which is clearly what happens when people are getting sprayed with pepper spray.

TWILLEY: Or you know, unpacking a shipment of Carolina Reaper from their co-host and supposed friend. Ahem.

GRABER: And actually, people in South and Central America used chiles in war. They’d make grenades with ground chiles in them and launch them at attackers and leave their enemies basically choking and blind. Another tactic was to put the chiles in what were kind of like water balloons so they’d ferment and then burst on impact, releasing all their noxious, painful gases.

TWILLEY: Cynthia was taking notes. Clearly.

GRABER: I don’t know how to defend myself here. I promise, I don’t have a vendetta against Nicky I’ve been keeping secret all these years.

TWILLEY: Long story short, capsaicin is a potential weapon in the hands of your enemies, thank you, Cynthia. This is not even just a historical curiosity: the Indian army has been working on a chile grenade as a non-lethal but very effective weapon.

GRABER: But of course as we’ve already said, the chile pepper’s burn is something that a lot of us find pleasant and exciting—in somewhat smaller doses.

TWILLEY: Although the right dose varies by person—some people genetically have fewer receptors that get triggered by capsaicin, so they feel less pain from hot chiles. And you can also train yourself to feel less heat just by eating hotter chiles regularly: scientists think your receptors get less receptive if you’re constantly feeling the burn.

GRABER: But what if you’ve accidentally gone a little too far in your chile pepper training regimen and the burn feels, well, really burny. What do you do?


MCGEE: For the most part, the way you quench the burn of chile peppers is with time. So you quench it with suffering. You can’t ameliorate the effects while the burn is subsiding, because, unfortunately, the burn is occurring because the molecules have gotten into the cells of your mouth. And once they’re in, you can’t really get them back out again. So you have to deal with the consequences of their being in there.

TWILLEY: Thanks Harold. But yes, his doom and gloom is true: the bits of capsaicin that have already bound to your receptors—there’s not much you can do. Pam says you can get some very temporary relief by drinking something cold—cold obviously counteracts the sensation of heat. But capsaicin isn’t water soluble, so cold water won’t help for long.

GRABER: But there will be more capsaicin molecules and bits of pepper still floating around on your tongue and in your mouth. And you can cut them off before they manage to bind with the receptors in your mouth. One way is to wash them away with something fatty, because capsaicin is soluble in oil.

TWILLEY: And you can even break the chemical bonds of these free floating bits of capsaicin using one of the proteins in milk. So dairy is your friend—it’s fatty and it has this magic protein.

DALTON: And, you know, if you look at cuisines where they use a lot of that, it’s often the case that they will have a milk-based drink. Like in India, a lassi, or a yogurt dip somewhere nearby to sort of quell the burn of the capsaicin.

GRABER: And if you want to combine all three—a milk product, lots of fat, and something really cold—I recommend ice cream. It’s what worked for me after our tasting was done.

TWILLEY: What is more questionable in its efficacy is the classic accompaniment to a spicy curry: beer. Capsaicin is soluble in alcohol.

MCGEE: The problem with beer is that, unless it’s a British ale, it’s going to be more or less carbonated and carbonation triggers acid sensations. And it turns out that acidity is another thing that can actually aggravate the receptor that reports that capsaicin is there.

DALTON: And perhaps if you drink enough beer, you stop worrying about the capsaicin burn. And that’s really where the relief comes from. It’s a much more a cortical effect or relief of anxiety about it.

GRABER: I definitely wanted to be distracted from the burn in my mouth. But I didn’t pick up any booze, because we had more tasting to do.

TWILLEY: After the tepin we spooned yogurt all over our burning tongues and commiserated.

TWILLEY: I feel personally if I had been the ancestral person who had encountered those in the wild I would have been like, wow, I’m never putting that in my mouth again, but…

GRABER: But good for them!

TWILLEY: Good for them!

GRABER: After cooling down, we decided to take a step back and taste a mild pepper, we followed Maricel’s advice and moved on to taste another one of the five species, a chinense.

PRESILLA: Capsicum chinense has, you know, cultivars all over: Different colors, different shades, different levels of heat. For example, one of the favorite peppers of Peruvian cooks is something called ají panca.

TWILLEY: So we each opened up our jar of ají panca.

GRABER: Smells really good. Ooh, that’s lovely.

TWILLEY: We shouldn’t have done the other one first.

GRABER: No, because now I can’t tell if this is spicy or not.

TWILLEY: Yeah. At the moment, it has no spice to me.

GRABER: I think it has a tiny bit of heat.

TWILLEY: I’m having a little more of this.

GRABER: It’s really good.

TWILLEY: Mm. I’m starting to be able to taste again. And it’s nice.

GRABER: It was fruity, a tiny bit earthy, and it had just a little hint of heat. It was a really mild and lovely pepper.

TWILLEY: Staying in Peru, but with yet another different species of chile pepper, we moved onto ají amarillo. It’s a baccatum.

TWILLEY: The ají amarillo is amarillo. It’s definitely yellow.

GRABER: It is indeed, it’s very yellow. You’re gonna feel a little heat with this. This is one of my favorites. Oh my gosh, this tastes like Peru to me.

GRABER: While ají panca might be popular in Peru, ají amarillo is probably Peru’s national chile. I had it on dishes all the time when I was traveling there. It’s really common in a sauce for a potato dish and also in ceviche. I even had an ají amarillo ice cream there that I still dream about.

TWILLEY: It’s delicious. It’s rounded.

GRABER: So good.

TWILLEY: It’s warm. It dissipates pretty quickly. Like, I’m not left with this lingering burn.

GRABER: No, that’s true.

TWILLEY: I like it. This is my favorite so far by quite a long shot.

GRABER: It’s so good.

TWILLEY: And finally, species number 4.

PRESILLA: Capsicum frutescens. And just think of Tabasco. Tabasco sauce is made with Capsicum frutescens. Very specific in terms of flavor, in a sharp… It does not have that muskiness of the Capsicum chinense, but it does have this almost vinegary quality. And most people who work with the Capsicum frutescens know that it’s fantastic for table sauces.

GRABER: Our frutescens chile that we’d bought was wiri wiri, they’re these wrinkly dried peppers that are about the size of a very large plump raisin. I had to look them up online because I’d never heard of them.

GRABER: So this is from Guyana, it’s a staple spice from the South American region. So common that most Guyanese kids grow up eating them. Delicious, tangy flavor, it says, delicious, tangy flavor. Delicious, tangy flavor, plus a lot of heat! Okay.

TWILLEY: Are you just saying that kid stuff to make me feel like a wuss here? But anyway.

GRABER: Oh, wait, I have to… swallow it. Oh I don’t think I can. No, I couldn’t swallow it.

TWILLEY: Oh, come on. You have to swallow it. I haven’t tried it yet.

GRABER: No… COUGH I spit it out and swallow just some of the seeds. I have to tell you my head is sweating. Like my scalp is sweating.

TWILLEY: My nose is running.

GRABER: Oh my god, Nicky, my mouth hurts so badly.

TWILLEY: Now my mouth hurts, I’m going to have some yogurt.

GRABER: I’m like writhing standing here.

TWILLEY: Did you get a flavor, I didn’t really get—oh god, my mouth hurts! What am I supposed to do? It hurts so much. Why won’t the yogurt… Make it stop! Wow.

GRABER: Yeah, that was something.

TWILLEY: It’s not really stopping.

TWILLEY: I have a lot of respect for Guyanese children now, and also a question: how did a spicy South American berry that I really regretted eating become such a staple in West Africa? I mean, how did the chile take over the world?

GRABER: This unsurprisingly will take us back to when Europeans showed up in Central and South America. Columbus and his crew, on their very first voyage in 1492, they were served ají with their food by the Natives in the Caribbean. And so Columbus brought some of those precious berries back to Spain with him.

TWILLEY: When Columbus set sail on the ocean blue, he was supposed to actually be figuring out a new supply chain for black pepper, which Europeans relied on and loved to spice up their food. That’s why he called these new hot berries peppers—they were like peppercorns, but on steroids, and peppercorns were a super valuable spice.

PRESILLA: And when he landed in Spain, besides you know, bringing samples of other foods even like turkeys, he gave a glowing report of the potential of the ají. You know, he called it a spice for large commercial possibilities

TWILLEY: And he wasn’t wrong. Chile peppers caught on quickly in Spain. Other new world crops like tomatoes and potatoes were initially thought to be a little suspect, chocolate was popular but only for the elite. But chile peppers were a smash hit with all sectors of society.

PRESILLA: If you had a hot pepper plant growing in your garden, then you wouldn’t have to spend a lot of money on peppercorns, which were very expensive. And there was a point, you know, that everybody was using it.

GRABER: You couldn’t grow black pepper in your garden in Spain, but you could grow chile peppers, pretty much anywhere.

PRESILLA: In fact, in literature, Spanish literature, there’s a reference that with peppers, the lord ate as well as a slave. So there was a democratization of the use of peppers in Spain.

TWILLEY: Like the women Maricel saw using the ají to make a very spartan diet into a delicious cuisine in Peru, Spanish peasants started relying on chile peppers to do the same thing.

GRABER: Chile peppers became so popular in Spain that the Spaniards even developed their own varieties, like the pimenton, and padron peppers.

PRESILLA: And every region, you know, has a different predilection, you know, for particular peppers, for example, if you go to Rioja, is that something called pimientos choriceros, you know, which translates as the pepper for chorizos, for sausages.

TWILLEY: Spain’s neighbors, the Portuguese, also got into the chile pepper action early. And they were really the ones that spread chiles around the globe—Portuguese sailors brought chiles to West Africa and to the Middle East and to South East Asia.

GRABER: The Portuguese brought peppers to India, where they quickly became essential. Chile is central to the cuisines of Bhutan, and Korea. But arguably the largest country that today is the most closely identified with  the chile pepper, among all the many nations that couldn’t possibly imagine eating without chiles—I’d say maybe, probably, the winner is China.


TWILLEY: Like everywhere, the chile pepper first came into China through port cities. And it was quickly adopted, at least in certain regions.

EDWARD WANG: From the 17th century onward, then, there were pretty systematic records about the foods people eat in these regions. Guizhou, Hunan, Hubei, and Sichuan were spicy.

GRABER: Edward Wang is head of the Asian Studies program at Rowan University. And he says those regions adopted chiles for a number of reasons—first and most importantly, because the people who lived there were poor. Like in Hangzhou, one of the poorest regions in China.

WANG: And particularly that region lacked salt. So before chile peppers, they actually use vinegar to spice up their food. That was one of the reasons that people used chile peppers, that the taste of like hot to replace the shortage of salt.

TWILLEY: The chile pepper is a remarkably adaptable and unfussy plant and it grows well in all kinds of different environments—humid, dry, mountainous, coastal. So that helped it spread.

GRABER: And then in China, chiles were even more of a hit because of their color.

WANG: That definitely has an impact because red is a festive color. Right, so in weddings and New Years, major holidays, and people hang dried chili peppers at their doors. And that definitely brings a certain type of happiness to their household. That possibly also adds some reason to the popularity of chili peppers in those regions.

GRABER: So chile peppers were pretty and auspicious, and they were relatively free, since you could grow them yourself. And Edward says this last advantage was particularly key, because poor people in China, like in South America, they had a pretty bland, starchy diet of a lot of grains. Edward said food was divided into grain food, and non-grain food.

WANG: So that’s why initially chile pepper was adopted as like a salt, because if you just eat the grain food, then maybe it was too bland, right. So you need to have something else to consume them. And so in Chinese language, you have words like [CHINESE], it means “down the grain.”

TWILLEY: Down the grain like literally, get it down you.

WANG: So they will use chile peppers or salt or pickles to down the food.

TWILLEY: But in China, even among people who could afford more than just grains, chiles fit into a certain way of thinking about food—a culinary style that valued combining lots of different tastes to make a meal.

GRABER: At one point in time, Europeans ate richly spiced foods, too, but, by the time the chile pepper came around, this wasn’t a strong tradition, Europeans had started to focus more on the essence of the meat or fish itself, rather than combining sour and spicy and sweet in one dish, in a way that was particularly valued in some regions in China.

TWILLEY: Chile peppers didn’t really catch on in Northern Europe at all, and in Italy they were carefully bred to remove all their spiciness, to become bell peppers.

GRABER: In China, though, spicy chiles became so deeply entrenched in some regions that many Chinese think the plant is native.

WANG: Most of the people would answer that, “Well, that’s from Sichuan, from Hunan.” Just like the tomato, right? Tomato, people wouldn’t think that it was like from the Americas. I mean, it was so adopted into the Chinese cooking.

TWILLEY: Chile peppers have become entwined with Chinese identity—they show up in poetry and slang, they embody all sorts of positive qualities.

WANG: Hot-tempered and courage. Manhood, maybe. Masculinity. For girls, you have a term called lamei right? La means spicy, and lamei is, I would say pretty positive to describe a woman who is more kind of adventurous. And, not shy, not like timid. So that’s the opposite to the traditional type of Chinese woman. And they will regard those women who became like entrepreneurs or say, “Oh, well, she’s from that region. She’s so risk-taking.” And those are all, I would say, mostly positive images. There are no negative associations with eating chile peppers.

GRABER: And even in regions of China that had a tradition of blander foods, that didn’t adopt the chile pepper originally—well, today, they’re getting spicy, too.

WANG: In the 1960s, 70s when I grew up, chile peppers were not that popular among certain regions. They may have been popular in Sichuan, in Southwestern regions, like Guizhou, like Hunan, those provinces. And we had known that “these people love spicy foods.” But now of course, my relatives, my friends in Shanghai are becoming addicts to spicy food. This is why my interests became inspired, I would say: why over the last 30 years did spicy food become so popular?

TWILLEY: Edward’s theory is that it’s because of mass migration in China in the last couple of decades. Poorer people from regions that relied on chiles to get the grain down moved to the richer cities to work and they brought their peppers with them.

WANG: And now, of course, even in Guangdong—Guangdong’s cooking was very mild. I would say they emphasize freshness and a lot of fish and so on. But again, if you go to Guangzhou today, then you will find a lot of spicy food.

GRABER: Everywhere feels like it’s getting spicier today. Food in America used to be thought of as pretty bland. Although I do have a point of pride here that the first ad for hot sauce in America was published in a Massachusetts newspaper in 1807. Not that it had a huge impact on traditional New England cuisine.

TWILLEY: Honestly, in general, the North American chile scene was pretty mild—don’t come at me, Texans, with your chile queens etcetera—I’m talking in general, compared to say, China, or south of the border in Mexico, the U.S. was just not especially spicy.

GRABER: That’s been changing. In 2004, hot sauce and salsa finally conquered ketchup, mustard, and mayonnaise to become the very top two condiments sold in the U.S. Congrats, America, good job.

TWILLEY: And you know America: we’re in it to win it! All those lovely chile peppers developed elsewhere in the world are nice, but we want the hottest of them all!

GRABER: Speak for yourself. I’m not part of that “we.”

TWILLEY: I’m channeling the chileheads. And there are a lot of them out there.


EMCEE: You are embarking on a culinary journey…

WOMAN: I love the pain of spicy food.

EMCEE: …that will probably not rest well with you.

WOMAN: It awakens the soul. Wooooo!

EMCEE: It’s hell night, baby!

COON: It is absolutely a trend. And I don’t think it’s a trend that’s going to end anytime soon. I thought when we first discovered the ghost pepper, back in 2006, I believe, we were like, Okay, this thing’s really hot, people are really interested in it.

TWILLEY: The ghost pepper is known as the bhut jolokia, which means Bhutanese pepper in the local language. It’s a mix of a frutescens and a chinense and it had been growing in Assam in India, no one knows for exactly how long. But it wasn’t widely known outside the region at all, until the 1990s. And it’s credited with starting the super hot revolution.

GRABER: Danise is a breeder at the Chile Pepper Institute, as we mentioned, and she pays very close attention to what people want to eat.

COON: And then, you know, four or five years later, we discovered the moruga scorpion, and it was twice as hot as the ghost pepper. And we’re like, okay, people are really interested in this too. And then just, you know, hundreds of thousands of hot sauces out there that are made with these super hot chiles. And it blows my mind because I prefer flavor. And when it gets to like 1 million Scoville Heat Units, it’s nothing but pain, and you don’t care what it tastes like at that point.

TWILLEY: Just as a point of reference, that wiri wiri that set our mouths on fire was about two hundred and twenty five thousand Scoville, and a jalapeño maxes out at puny eight thousand Scoville.

GRABER: But what do those thousands even mean? Where does this Scoville thing come from?

COON: So it was actually developed in the 1950s by a scientist. His name was Wilbur Scoville. And he wanted to figure out a way to kind of give people an understanding of how hot chile peppers were. So he set up a human subjects taste panel and gave them samples. And every time they tasted it, he would dilute it. And then they’d taste again. And then he’d dilute it again. Every single time they felt heat, he would dilute it, and that would be a single Scoville Unit.

TWILLEY: So if you had to dilute the chile pepper solution five thousand times before you couldn’t feel the burn, you’d end up with a pepper that was rated at five thousand Scoville Units.

GRABER: If this seems like a weird and kind of arbitrary measuring system to you, it is. People have very different sensitivities. Scoville did try to get around individual differences by having a panel of five people—

TWILLEY: But there’s a larger issue that Pam pointed out. Desensitization.

DALTON: One interesting thing about capsaicin is that you can have this acute desensitization where you eat it and you consume for maybe five or 10 minutes, and then you stop and you wait about 15 minutes. And when you go back to it again, it will not have anywhere near the same burn or experiences as before. And so you can do some pretty interesting challenges with people, if you kind of pre-game and then pick up like a buffalo wing or something very spicy when they haven’t had the opportunity to pregame. Because you will be acutely desensitized and you can eat it with absolutely no effect. Whereas that person will be screaming at that point in time.

GRABER: So pranks aside, what this means is that Scoville Units are kind of ridiculous. The original setup Wilbur created relies on the tester knowing when they can’t taste the spice of the pepper anymore, but the pepper is making it harder to taste pepper!

MCGEE: And so I think people are moving to simply giving capsaicin levels, which is something that’s objective and easily measurable. But Scoville Units are still much referred to.

GRABER: Even though today scientists like Danise and her colleagues do measure the actual capsaicin in any given new variety of pepper and then they can convert that to existing Scoville Units using a formula.

TWILLEY: Because Scoville Units are what the chileheads are chasing. Before the 1990s, there were only a couple of known chile peppers that were rated above three hundred thousand Scoville Heat Units—the Scotch bonnet and the habanero.

GRABER: But now the Guiness Book of Records has a couple dozen varieties competing for the absolute hottest, and they are all over a million Scoville Units. These are called super hots.

TWILLEY: And it all started when Danise’s colleague at New Mexico State collected the bhut jolokia or ghost pepper near Assam in India, and brought it back to test it and study it. Turns out, super hot peppers are botanically different from regular peppers. The capsaicin isn’t confined to the white placenta stuff.

COON: We discovered probably about six or seven years ago at New Mexico State University that a lot of these super hot varieties like the ghost pepper, and the scorpion, they actually produce these vesicles that house the capsaicin in their walls as well. So that’s why a lot of these super hots are really, really hot chiles and produce a lot of capsaicin.

GRABER: So that’s the biology of the superhots, but now superhots have become a competitive sport. On the plant side, breeders are racing to see just how hot they can get a pepper to be.

COON: Yeah, so the hottest anything can be is actually 16 million Scoville Heat Units. And that’s pure capsaicin.

TWILLEY: But actual chile peppers are nowhere near that yet, and they never will be—capsaicin is a costly molecule for the pepper to manufacture and a plant can’t produce more than a certain amount without failing at all the other things they need to do to survive as a plant.

GRABER: But breeders don’t know what that limit is, and they don’t think they’ve reached it yet, they’re still pushing the limits of plant-induced pain.

TWILLEY: Because chileheads love it. And they are also in a competition for who can eat the spiciest pepper of all.


ANNOUNCER: Come on down!

MAN: I salivate for hot food.

VO: We produce some of the hottest food in the world.

ANNOUNCER: Hot food, please!


EMCEE: What we have got in front of us… is a basket of hatred. Each person will be given a pepper from this basket. Then you will have a maximum of 15 seconds to eat that pepper.


MAN: It’s time to reach for that jug.

SHAQ: You lied to me and you—Oh!!! Ohhh. This one got me. COUGHS

TWILLEY: OK but a wiri wiri was already too hot to even taste the flavor for me, why on earth are people setting their mouths on fire with a million Scoville pepper? Why would you even want to do that?

DALTON: This is an area of research where people have looked at the degree to which people who like capsaicin in large amounts have a tendency to be sensation seekers. It’s almost like you are exposing yourself to something that is dangerous but not really dangerous, right? So it’s like a rollercoaster ride. If you assume that they’ve maintained the roller coaster properly, it’s going to be scary but you’re pretty sure that you’re going to come out okay on the other end. The same thing with capsaicin. It’s sort of triggering the brain into, “I’m doing something dangerous here.” And then you have this post-danger euphoria from having survived the experience with nothing more than maybe a little bit of soreness on your tongue.

GRABER: Unsurprisingly to me, chile competitions tend to be a kind of chest-beating macho type thing. Not my speed.

TWILLEY: Plus it’s not all fun and games. One guy who ate ghost pepper puree at a contest in 2016 ended up in hospital with an inch long tear in his esophagus from the irritation. The doctors who treated him said it was because of all the post-chile vomiting.

GRABER: Another reason to skip the chilehead competition. But, unfortunately, Nicky and I had our own tasting to do. And the wiri wiri we tried wasn’t the hottest. The Carolina Reaper is considered the hottest pepper available today. It’s about a million and a half Scoville Units. And as you listeners already know, I bought two jars from a local store and I shipped one to Nicky.

GRABER: Are you ready?

TWILLEY: Will I ever be ready? BAG RUSTLING. Do you have some?

GRABER: I have some. I’m gonna just take the tiniest bit on a tiny bit of my tongue. Okay, are you ready?

TWILLYE: Yeah. 3-2-1.


GRABER: Now before our big reveal, we were warned by the owner of Chistina’s Spice store that we should just dip the tiniest edge of our pinky finger into the powder and taste just the tiniest few grains of it. And after eating the entire wiri wiri—or rather spitting it out—I wasn’t taking any chances. I wanted to minimize the coming pain.

TWILLEY: After inhaling it the day before, I too was a little wary. I took like a forensically tiny amount on my pinkie and put it in my mouth.


GRABER: My throat hurts.

TWILLEY: RASPY At first I was like there’s nothing, and now there’s… COUGHING

GRABER: And now I’m not putting the rest of what’s on my finger into my mouth because…

TWILLEY: I touched my finger to my lips on the way out and that is burning.

GRABER: I did not do that. And I’m not going to.


GRABER: I think I’m going to rinse my finger off.

TWILLEY: You’re smart. You’re a smart lady.

GRABER: Ooh. But it does hurt my throat. Wow.

TWILLEY: My throat hurts, my nose is running.

TWILLEY: We went and washed our hands and ate some yogurt and coughed and blew our noses.

GRABER: My mouth hurts really badly.

TWILLEY: It really hurts. Like it actually hurts. Still.

GRABER: Yeah, it’s pain. No, like, it’s like serious pain in my mouth.

TWILLEY: I mean this Carolina Reaper, I’m never gonna touch this Carolina Reaper again. I don’t know why it even exists. It’s horrible.

GRABER: This pain went on for many minutes.

TWILLEY: Why is it still burning? Okay, this is just… I’m going to go spoon some yogurt into my mouth for a while.

GRABER: I’m gonna go lay down. Okay, bye.



GRABER: Don’t worry, our experience with the wiri wiri and the Carolina Reaper did not put us off chiles, we still enjoy hot sauce and chile crisp and mole and harissa and aleppo and urfa flakes and more, liberally. We are committed chile lovers.

TWILLEY: Just not chileheads.

GRABER:  A quick shout out to the local Somerville store Christina’s Spices, which does ship all around the country—they have the best selection of chiles I’ve found anywhere online, even compared to places that specialize in chiles. We’ll have a link if you want to do a tasting yourself on our website,

TWILLEY: And if you want to do a tasting, you’ll want the New Mexico State University Chile Pepper Institute chile tasting wheel, which Danise helped develop. It’s got heat profile notes and flavor notes and it’s a lot of fun to use.

GRABER: Thanks this episode to Maricel Presilla, Danise Coon, Harold McGee, Pam Dalton, and Edward Wang, we have links to their books and research on our website,

TWILLEY: There’s a bunch of chile stories we couldn’t tell this episode—and we saved the forgotten story of the man whose work founded the Hatch chile phenomenon for our special supporters newsletter, which you can sign up for on our website, gastropod dot com slash support. And we’ll be back in a couple of weeks.

GRABER: Till then!