This is a transcript of the third “Ask Gastropod” episode, Why Are Kids Dipping Cookies in Ranch, Are Food Comas Real, and What’s Inside the Mummy’s Stomach?, first released on December 18, 2024. It is provided as a courtesy and may contain errors.

JOSH: Hi, my name is Josh Goslowsky. I’m from Chattanooga, Tennessee. And I have a question for you about ranch, ranch dressing. I’m curious about why it’s so popular, and where it comes from.

LAURA: So, hi, I’m Laura calling from Salt Lake City, Utah, and my question for Gastropod is, what is a food coma? And is there anything I can do about it once I have one, other than taking a nap?

NICOLA TWILLEY: Gastropod listeners are a curious bunch, and we say that in the fondest possible way.

CYNTHIA GRABER: Because we ourselves are endlessly curious, that’s why we launched Gastropod. We love hearing your questions, too, and this episode, we’re here with some answers!

TWILLEY: Gastropod is, of course, the podcast that looks at food through the lens of science and history. I’m Nicola Twilley.

GRABER: And I’m Cynthia Graber, and our end of the year gift to you is the answer to some of the mysteries that have been keeping you up at night. Like—why is everyone dipping everything in ranch dressing these days? And also what is ranch?

TWILLEY: Plus some seasonally appropriate science: what’s actually going on biologically when you eat too much at a holiday meal and fall asleep drooling on the couch?

GRABER: And finally, another seasonally appropriate topic: it’s not quite a snowman, it’s an ice mummy! Or rather, Ötzi the Iceman. We’ve got the story of what’s in his stomach, what that tells us, and why it took scientists two full decades to find his stomach in the first place.

TWILLEY: But before we dive headfirst down these fascinating rabbit holes, we’ve got a request for you. Gastropod is just me, Cynthia, and our producer Claudia, we are a tiny team, and we work really hard to bring you every single episode.

GRABER: And when we say really hard, we mean it. We read books and scientific papers and we find people to talk to and figure out how to tell their stories. There is a huge huge amount of behind-the-scenes work that you don’t see, but I can promise it is always going on.

TWILLEY: And to make that work possible, we need funding. We make some money from advertising, and we have grants from a couple of generous foundations, but we also rely on you, our listeners, to give us the support we need to keep going.

GRABER: We know a lot of people are asking for support these days, and we also know it’s not possible for everyone to give. But if you enjoy the show and if you can, we’d deeply appreciate it. There are perks at every level of giving, but really no amount is too small—or too large! Gastropod.com/support or find us on Patreon. And thank you. We so appreciate every single one of you.

TWILLEY: This episode is supported in part by the Alfred P. Sloan Foundation for the Public Understanding of Science, Technology, and Economics, as well as by the Burroughs Wellcome Fund for our coverage of biomedical research. Gastropod is part of the Vox Media Podcast Network, in partnership with Eater.

[MUSIC]

AYELET: My name is Ayelet and I am from Cambridge, Massachusetts.

GRABER: Our first question this episode comes from one of our teenage listeners. Ayelet really enjoys listening to Gastropod episodes—often more than once.

AYELET: My favorite gastropod episode is The Queen of Kiwis, which I listened to for at least two full weeks on repeat at 3-4am when I would wake up in pain after my tonsil removal surgery.

TWILLEY: This was confirmed for us by Ayelet’s long-suffering mother, Aviva.

AVIVA: And it is a fabulous episode, but one has to admit that at a certain point one has listened to it many, many, many times.

AYELET: I never got tired of it.

GRABER: Ayelet’s question is not about kiwis, we had that covered. Instead, she had a question about Ötzi the Iceman, who as it happens was discovered before Ayelet was even born.

BROADCASTER: It’s been hailed as one of the century’s most important archaeological finds: the body of a Bronze Age mountaineer, which scientists believe could be 4,000 years old.

AYELET: He’s an old dead guy. So yes, that falls right into my category of interest. ….I would like to clarify that what I mean by old dead guy means pre-historic old dead people. [LAUGH] It doesn’t have to be a guy. But I don’t mean, like, I’m interested in Thomas Edison, he’s actually frankly quite boring. But if you give me an archaeologic mystery I will sit reading about it for days

TWILLEY: We are not here to judge, we also love old dead people of all sorts. So Ayelet had lots of questions about Ötzi, but the big thing she wanted us to answer was: what was in his stomach?

AYELET: I want to know what he ate. If it was like a rabbit that lived in the mountain, or like a wildflower, or if it was rations that he had.

GRABER: So we called up Frank Maixner, he’s a scientist at the Institute for Mummy Studies in Italy, which is an amazing thing. And for those of you who aren’t familiar with Ötzi, Frank had an introduction.

FRANK MAIXNER:. The Iceman, what—Tyrolean Iceman it’s also called, or he, he has a nickname Ötzi. Is actually a, a glacial mummy, which was discovered in the year 1991, by German hikers here in the border between Austria and Italy.

TWILLEY: We don’t know Ötzi’s real name of course, but his nickname comes from the particular mountain range where he was discovered, the Ötzal Alps.

MAIXNER: It was discovered still sticking in the ice, a mummy, which originally was thought that it was maybe a hiker who died up there. But, over some days then, radiocarbon dating told us that he’s actually 5,300 years old.

GRABER: Ötzi is Europe’s oldest known mummy, which made finding him incredibly exciting. You’ve probably heard about Egyptian mummies, but Ötzi is different. In Egypt people mummified the dead on purpose, and they did it by removing a lot of the internal organs and then slowly drying the bodies out.

MAIXNER: Yeah, in contrast to Egyptian mummy, the Iceman is a so-called natural mummy. So the Iceman, actually, was somehow freeze-dried up there. Then the cold temperature, the glacier surrounding him, kept all the tissue, the organic tissue around him, and this resulted in this very exceptional preservation, actually.

TWILLEY: Finding Ötzi was like winning the old dead guy lottery! And scientists immediately set about trying to find out all sorts of things about him. They found out he was probably about 45 years old when he died, that he was about five foot three and 110 pounds, and that he had lots of tattoos—which are some of the earliest tattoos that have ever been found.

GRABER: What they didn’t find, at least at first, was his stomach. But they wanted to know what he had been eating. So some scientists analyzed his hair to find evidence of nutrients from food, and from that they thought he was a vegetarian.

TWILLEY: That conclusion was quickly revised though, because other researchers were analyzing samples from his lower intestine. So that’s like, proto-poop? Digested matter that’s on its way out the door. And they did DNA analysis on this stuff and found red deer DNA, so it seemed like Ötzi definitely ate meat too.

GRABER: But there were two problems. One, the tools they were using to analyze the intestinal remains didn’t work very well. Ancient DNA is really degraded, and at the time scientists were using tools that needed pretty long chains of intact DNA, so they weren’t great at figuring out what those fragments meant. And two, a lot of food is absorbed by the time the food makes its way from the stomach all the way to the lower intestines, so a lot of stuff was lost.

TWILLEY: But then Ötzi got a new CAT scan in 2009 and the radiologist spotted… a stomach! It was there all along, but it had been kind of hidden. Part of that is that internal organs in a mummy do not look the same as the ones in normal dead bodies.

MAIXNER: Yeah, the mummification for sure changes also the inner organ structures. And, lungs, for example, get—they shrink, to a size where they hardly can be found anymore. And this, upper part under the ribcage was then, where the stomach was found, so in an anatomically unusual position. So it moved upwards. It was not anymore at the position where you would expect a stomach.

GRABER: But they found it, and it turned out that it was full of food. So obviously they wanted to sample the stomach to get at that food. But this was a big deal, Ötzi had only had physical samples taken twice in the 20 years since he’d been uncovered.

MAIXNER: And then it was decided to do another sampling campaign. Which was not as easy since the Iceman is frozen. You need to defrost him also to get access to this samples.

TWILLEY: One thing to bear in mind here is that Ötzi is very, very fragile. Sure, he’s amazingly well preserved for a 5,000 year old guy, but like Frank says he has to be kept frozen and he has to be spritzed with distilled water on a daily basis to keep him from drying out. And if you destroy any tissues while you’re sampling—well then, those are gone forever, and future scientists with even better tools will never have the chance to study them.

GRABER: So scientists have to balance what they might learn with what they might destroy. Like for example, in theory the researchers could have maybe learned more about Ötzi’s diet from his teeth. It’s common to look at the plaque on teeth and maybe some fossilized bits of food that were stuck in someone’s mouth, but Ötzi’s mouth was frozen shut, and the scientists didn’t dare try to pry it open. But they were willing to give the stomach a try.

MAIXNER: Luckily, there was already an access point. People in Innsbruck, where the Iceman was initially stored, they made some also sections on the Iceman. And here was a small cut already present on the belly.

TWILLEY: To understand the contents of Ötzi’s stomach, Frank basically needed biopsies of the food itself and of the stomach wall. And getting those biopsies was super intense, he and his colleagues had to gown up and sterilize themselves, and then just be really, really careful.

MAIXNER: It’s very… it’s very, it’s a special moment for sure.

GRABER: After they got the samples, even before they did any molecular analysis on the DNA of the plants or animals in his stomach, they could figure out some of what he was eating just by looking at a bit under the microscope.

MAIXNER: You see initially already, that he was not vegan. He was not vegetarian. He had an omnivorous diet. Because we saw, on the one hand, plant remains, but we also saw—clearly, signs for animal fibers, muscle fibers present in his diet. So these two things already told us quite a lot. And then an archaeobotanist, if he’s very skilled—and we had one which is very skilled—could already tell us based on the plant remains, that it’s einkorn, actually.

TWILLEY: Einkorn is an ancient type of wheat. It’s one of the oldest cultivated grains.

GRABER: But of course Frank and his colleagues wanted to make sure that their visual analysis was accurate, and they also wanted to figure out what meat was in there. Luckily, not only were there more intact food bits than had been found in his intestines, but there were better tools to analyze ancient degraded DNA.

TWILLEY: Frank sequenced the ancient DNA and then the team compared it to genetic databases of European animals and plants to look for matches, and they came up with a menu for Ötzi’s last meal.

MAIXNER: I think the Iceman had a very balanced diet, I would call it. Having on the one hand cereals, then having also plant remains we would not have expected. Like the bracken fern, which is a toxic, actually, plant. And then it was supplemented by animal protein diet coming from the Ibex, but also from the red deer.

TWILLEY: An ibex is a kind of wild goat, with big curvy horns.

MAIXNER: On top it was lipid rich, so fatty diet. Which definitely makes sense in this altitude where he was walking to have an energy rich, also, diet.

GRABER: The one thing that did surprise them was that bracken fern, the one Frank said was poisonous.

FRANK: So this fern, which normally—yeah, it’s, it’s growing here in, in, in this area. It’s widely distributed in the woods. However, it’s toxic. And it was initially also assumed maybe this was just unintentionally ingested. Maybe he just wrapped his food with these fern leaves.

TWILLEY: But then they realized that there was too much of the leaf matter for it to just be a trace of a food wrapper. Ötzi must have chosen to eat it.

MAIXNER: And, over time we realized, okay, this is not the first case which is reported. There are other indigenous populations also, which are known that they eat the young spruces of this fern, which is less toxic also.

GRABER: Some scientists speculate that maybe he was eating it as a form of medicine, but there’s no way to know.

TWILLEY: This is not the only thing that Frank doesn’t know, even with his fancy new DNA analysis.

MAIXNER: So for example, the archaeobotanist also saw, saw some plant remains he could not address.

GRABER: They couldn’t find a match for those remains in the DNA database they have. They just don’t have every plant sequenced.

MAIXNER: In best case, for example, we would have a dataset of all wild plants present in the Alps. Ideally, this would be the reference dataset one would need. We are far away from this yet.

TWILLEY: But even though they couldn’t get a full ingredient list, they did gather some clues as to how the meat—the deer and ibex in Ötzi’s last meal—was prepared.

GRABER: They figured this out by doing some experiments themselves, they cooked meat and then they also dried meat to see how each process changed the muscle fibers.

MAIXNER: So one thing we realized is, for example, in the, in the, in the muscle fibers, that we don’t see any evidences for cooking or harsh heat treatment. So it seems to be that he more maybe air dried this meat. Similar to beef jerky.

GRABER: With the einkorn, they don’t know. Maybe it was eaten as bread, maybe as porridge, they couldn’t tell.

TWILLEY: Another thing this stomach analysis did shed light on is one of the biggest mysteries about Ötzi: how he died. We already knew he was killed, because radiologists found an arrowhead buried in his back, right below his collarbone.

MAIXNER: And this arrowhead ruptured an important arteriole. And led to an immediate, deep bleeding, actually, of the Iceman. So the Iceman was actually murdered up there.

GRABER: Scientists didn’t know if he’d been chased up the mountain, if he was running away from someone at the time. But then they found his stomach, and they saw that it was completely full when he was killed. So they realized that he wasn’t on the run, he was relaxing and enjoying a pretty substantial meal.

MAIXNER: We think that at that time when he ate his last meal. He felt quite safe. Otherwise you would not eat a complete meal, let’s say. This, at least, is our current hypothesis that at the time he felt quite safe and then he was shot to death.

TWILLEY: The plot thickens. But since Gastropod is not a true crime podcast, let’s get back to food and more specifically what this one man’s single meal can possibly tell us about how his community in Europe ate in general.

GRABER: Frank pointed out that sure, this is just one guy, it’s a snapshot of a single moment for a single person, but his stomach contents can give us some clues.

MAIXNER: For sure he lived in a time where- where it was not a pure farmer lifestyle. So it was, on the one hand, domesticated plants for sure. So we have the einkorn present. For the animal. We do not see any domesticated animals now in his, in his meals or in his diet.

TWILLEY: Frank’s colleagues have analyzed Ötzi’s clothing and found that his loincloth was made from leather from a domesticated sheep, and his shoe strap was made from cow leather. So his community did have livestock as well—but they clearly supplemented herding and farming with hunting and gathering. That’s kind of what scientists thought was going on food-wise in this part of the world at this time, but there isn’t a lot of evidence to go on, so it’s nice to have Ötzi to confirm it.

GRABER: Ötzi’s been with us for a few decades now, but we haven’t learned everything there is to know about him. He still has some secrets that Frank and his colleagues are trying to reveal.

MAIXNER: Currently we are working on the gut microbiome actually. So we see microbiome structures still, we can compare this also to modern microbiomes and, and this is very fascinating. He definitely has a more diverse microbiome. And there’s a big difference between our microbiome.

TWILLEY: The other thing Frank’s planning to do is use the more sensitive DNA tools he used on Ötzi’s stomach on other mummies that also have intact stomachs. Not all of them do, but Frank said there are some bog bodies from Ireland and freeze-dried mummies from South America that would be good to look at again with these new tools.

MAIXNER: So I think this is very exciting. So that we can even use old extracts, reanalyze them. So the whole field actually needs to do this. Because we are very limited in material, in samples also. And the samples are very precious.

GRABER: We’ll wait and see what food secrets those mummies have to reveal.

TWILLEY: I am here for more mummies. But in the meantime, buck up kids, it’s time to get into food comas! Are these medically real comas or just an excuse for not helping with clean-up? All will be revealed after this word from our sponsors.

[BREAK]

GRABER: We told you that Ötzi probably felt pretty safe when he was killed because he had a full belly, he had time to enjoy his meal. But what we don’t know is how he felt after the meal, like did he feel as lazy as our listener Laura?

LAURA: Especially around the holidays with lots of delicious food, and big family meals, I experience a food coma [LAUGH] after these large meals. And sometimes that interferes with other things that I want to be doing, right? Like I want to be going out or interacting with my family, playing games, going for a hike, whatever that may be. But I mostly just want to lie on the couch.

TWILLEY: So, a coma coma is a real medical condition. But is a food coma? We figured we should ask a scientist.

NIKOLAI KUKUSHKIN: A food coma is a behavioral response to eating food. When the animal, whether it’s human or another animal, slows down and relaxes after taking in a meal. So it’s exactly what it sounds. It’s not a literal coma, obviously. It’s a, it’s a relaxation. Another way to put it is: rest and digest. That’s a phrase that we use to describe that in maybe more scientific terms.

GRABER: Nikolai Kukushkin, he goes by Niko, he’s a life sciences professor at NYU. And we also turned to two other researchers who’ve also looked at food comas. Justine Hervé is a professor of economics at the Stevens Institute of Technology, and Subha Mani is a professor of economics at Fordham University.

JUSTINE HERVÉ: Basically it’s a decrease in alertness that happens, like within an hour, to two hours after ingestion of a meal.

SUBHA MANI: It’s just simple feeling of lethargy and fatigue. And usually associated with eating a nice big meal.

TWILLEY: One important thing to know is that a food coma is different from just feeling full.

HERVÉ: I think food coma is more associated with this idea of like, you know, a slowing down of your cognitive abilities. Or a feeling of drowsiness.

GRABER: And not all meals are equal when it comes to food comas. Researchers believe that larger meals, and meals that are heavier in carbs and fats, they’re more likely to lead to a food coma.

KUKUSHKIN: It depends on the person. It depends on the meal. It depends on the time of day. It might depend on your physical activity, if you went to the gym the day before. So as most things in our lives, it’s very hard to predict whether something like that will happen or not, just because our life is so full of many, many variables.

TWILLEY: But that feeling—you’re lethargic, you don’t want to get off the couch, you’re kind of glazed over—it’s a feeling. You feel like you’re more tired and kind of slowed down. But are you actually? Can you really not think or move?

HERVÉ: Much less is known about the possible consequences of that phenomenon, right? If there is like, a feeling of drowsiness and reduced alertness, does it mean that it actually leads to lowered cognitive or reduced cognitive abilities?

GRABER: Justine and Subha decided to look into this. Science has already shown that when we’re tired, we do more poorly on tests. And obviously, we feel tired when we have a food coma. But do they have a similar impact? Is a feeling of being tired after a big meal the same as being tired from lack of sleep? To find out, they did a study that involved more than 4000 students in India who were between the ages of 12 and 22.

TWILLEY: The students took a bunch of tests: tests in their native language, tests in English, math tests and a logic test. They all took them at slightly different times, whenever the test team came to their houses, which meant that some of them ended up taking the test soon after a meal, and some ended up taking it hours after they’d last eaten.

19:42 GRABER: Each student told the researcher when they had their last meal, and they also described how tired they were feeling. And then Subha and Justine and their colleagues sorted them into post-prandial, or after meal groups, based on whether they’d eaten within the past hour, or within the past two hours, or more.

TWILLEY: And it turned out that students who’d eaten within the past hour, wow, they suffered.

HERVÉ: Testing in the postprandial period reduced their, like, cognitive ability by like five to up to nine percent across the board. Like for all of these, you know, these types of tests. It’s a substantial reduction in your ability to perform.

GRABER: The results varied, but in general the students who had eaten within the past hour did even worse the harder the test was.

MANI: So, for instance, we find that the effects on you know, talking about levels of difficulty, we find that the effects are much smaller on their ability to read a letter and read a word. This effect is much larger for your ability to read a paragraph. So, you know, there’s quite a bit of gap between how food coma impacts your ability to read a word vis a vis your ability to read a paragraph.

TWILLEY: So Justine and Subha found that taking a test after a meal does cause a pretty big dip in performance, and the harder the challenge, the bigger the dip. Then they looked into why.

HERVÉ: Like one possibility could be that, you know, In the postprandial period, students just like feel more fatigue and though they exert less effort on the task. Another possibility is that they do exert effort, but they just they lack the cognitive ability to solve the question. You know, it’s like your brain is foggy. And even if you try, you just don’t manage to do it.

GRABER: Researchers usually use the amount of time a student takes to complete a test as a stand-in for ‘effort,’ and in this study, the students on average took roughly the same amount of time on the test, regardless of when they’d eaten. So Subha and Justine say that that ones who took their test within an hour after their meal, they did try as hard, they just didn’t have the juice.

HERVÉ: The idea that the problem is not about them exerting less effort. It’s about… you know, individuals having less capacity, cognitive capacities or like—like that, you know, there’s a depletion of their cognitive capacity to solve that question.

TWILLEY: In other words, the food coma is real. From their data, it seems as though the effect is stronger in adolescents than older teens. It also wears off after that first hour post meal—and sorry, Subha and Justine didn’t have any solutions for our listener Laura, to speed up that recovery.

GRABER: So there’s nothing we can do individually to get rid of a food coma, but is there something schools should maybe do if a food coma affects a student’s cognitive abilities?

MANI: We have clear evidence that timing of tests matters, digestive fatigue matters. So you maybe, after a meal, you give children a short break, or a nap, to restore their cognitive fatigue. Or at least, change the schedule in a way that easier sections are done after meals. And more harder sections, on math or language or something, is kept for early parts of the day or later parts of the day. When children have greater cognitive alertness.

GRABER: But Subha told us we shouldn’t assume this research holds true for all students around the world. The students they studied are particularly poor, and they don’t have high levels of education.

MANI: So I think the reason we’re seeing these big effects is because this is where there is very poor learning outcomes to start with as well. Which is why even a small, you know, food coma, fatigue, and cognitive resource depletion that comes from eating a meal has all these bigger effects that we see.

TWILLEY: Subha pointed out that it could easily be that for higher income students in richer countries, the effect of a food coma on test performance wouldn’t be nearly as big. That’s something Justine said they still want to study.

HERVÉ: I think one first question is, do these results hold in other contexts? A second question could be, does it have an effect on your learning ability? Not even just your ability to test, but your ability to learn also in that time period.

GRABER: And then also, the biggest question of all is, why do we get them in the first place, what’s going on?

TWILLEY: Over the decades researchers have proposed a variety of mechanisms that might lie behind the food coma.

HERVÉ: The medical literature started with, explaining food coma as like a diversion of the blood flows, like away from the brain and towards your digestive system. And that’s why you would feel more sleepy after eating.

GRABER: I heard this all the time when I was a kid, I had this mental image that like the blood had all pooled around my stomach. But that doesn’t seem to be the main thing that’s going on.

KUKUSHKIN: Another one to mention is tryptophan, in turkey. There’s this long standing idea that turkey has the special property of inducing a food coma, because it is rich in tryptophan. Which is a basic amino acid, so any food would have some amount of tryptophan. But turkey does happen to have a little more of it.

TWILLEY: The idea here is that when your body digests tryptophan-rich foods, it turns them into melatonin, which works with your circadian rhythms to make you feel drowsy.

KUKUSHKIN: But I think that theory has also been disproven. It doesn’t appear to have that much of an effect, and even very tryptophan rich foods might not necessarily induce a food coma.

GRABER: There are even theories that food comas aren’t really a thing, it’s just a natural circadian rhythm and you’d tend to feel more tired in the late afternoon anyway, at about the same time as you might finish eating a large lunch. But Subha and Justine’s study shows that’s not true.

HERVÉ: Because what we show in the paper is that this phenomenon exists at different hours of the day. So whether, like, after a meal in the morning, after a meal in the afternoon, or after a meal in the evening, we do find this decrease in performance everywhere.

TWILLEY: It’s so funny, this sensation we all know, we’ve all experienced, but up until now science has kind of drawn a blank.

HERVÉ: What’s very interesting is that so far, there’s no definitive answer on the cause of this phenomenon. We just know it happens.

GRABER: But recently, Niko thinks he may have found a biological explanation for food comas, and he started looking into this kind of by accident—when he was studying how memories form in sea slugs.

KUKUSHKIN: Sea slugs are much simpler animals. Their brains are much simpler. Their memories are very simple. And so we can get access to the most basic components of what makes a memory in an animal. And that’s why we’re interested in sea slugs.

TWILLEY: Sea slugs look like the blobby gelatinous sea creatures of your nightmares. But they are very useful to researchers. Kind of amazingly Niko used to get his from a guy who had a boat called Slugger, but now he just buys them from a couple different companies.

GRABER: When he gets the sea slugs into his lab, Niko puts them in aquariums, and to keep them contained, but still give them something to wander around, he buys them pasta colanders.

KUKUSHKIN: Pasta colanders supported by some foam, so they’re, they’re floating. And that’s where they hang out. They mostly just run around in circles around that pasta colander.

TWILLEY: Run might be an overstatement here. Things are very low energy in sea slug world.

KUKUSHKIN: They’re not… super exciting animals. They they don’t have a huge behavioral repertoire. They move around, they wave their head. And they wait for us to bring them seaweed. They prefer red seaweed. But we don’t always have that, so we usually feed them sushi nori. So our lab smells, often, like sushi. We had students who could not eat sushi after doing a PhD project in our lab.

TWILLEY: Sometimes you have to suffer for science.

GRABER: So Niko knew from other research that there’s a particular insulin-like hormone that a rat makes, and if you inject that hormone into their brain, you can strengthen their memories. He wanted to know if this same hormone would strengthen the memory of a sea slug.

TWILLEY: Wait up just one moment there: I am curious exactly how you would know if a sea slug’s memory was strengthened? It’s not like you can give them a test!

KUKUSHKIN: This has been studied for many decades and we understand precisely how that memory is formed at the level of individual neurons. So what we can actually do is pull out those individual neurons and have them in a petri dish.

GRABER: When sea slugs have their neurons in their bodies, and you give them a little shock, they pull in their tail. If you shock them again, they pull it in faster, which means they remember the shock. And you can mimic this in a petri dish with a dose of serotonin. You might have heard serotonin is sometimes called the feel-good hormone in humans, but it does a lot of different things in humans, and in other animals. And in sea slugs, it’s the chemical their brain produces when they’re shocked.

TWILLEY: Okay, so that’s the sea slug memory test. And so then what Niko did was get hold of that insulin like hormone that boosts memory in rats. He added that to the mix, and he waited to see what happened.

KUKUSHKIN: And we saw that if you add an insulin-like peptide into that petri dish, and simultaneously put that splash of serotonin, this danger chemical—the connection between the neurons gets enhanced more strongly. It’s a, it’s a stronger formation of a memory between those two neurons.

GRABER: That’s great, it worked! But as we said this is an insulin-like hormone, so it makes sense that it’s released when the animal eats. Niko wanted to know if maybe it would slow the animal down, literally give it a kind of food coma.

TWILLEY: So Niko set up an experiment where he did two things. Some of the slugs just got their regular nori rations, and some got their seaweed dinner plus an injection that blocked their receptors for this particular insulin-like hormone. And then he waited again.

KUKUSHKIN: It takes them a long time to eat that. It takes them like an hour to even find it in that colander. And then another few hours to munch on it. It’s, it’s an interesting thing to watch.

GRABER: Niko’s being more than slightly sarcastic. Because here’s the problem: he wanted to find out if they slow down after eating, but it sounds like sea slugs are already so slow, that like, how would you even know if they’re slower than usual, if it already takes them hours to eat? How do you figure out if they have a food coma if they pretty much look like they’re experiencing a food coma all the time?

KUKUSHKIN: One thing that I’ve learned about these animals is that if you want to understand an invertebrate, you have to, you have to speed it up. Twelve to 20 times for sea slugs. And then, suddenly, they start making sense.

TWILLEY: Their lives just happen at a slower pace than ours. So Niko had six colanders full of slugs, and he installed cameras above them, and he recorded many, many hours of footage of the sea slugs doing their thing, very, very slowly. And then he compressed all of that into just one hour

KUKUSHKIN: And then, I sit there. And I watch those six colanders and I mark on my keyboard what each slug is doing. This is the single most boring experiment that I ever did in my life. It was incredibly difficult not to fall asleep.

TWILLEY: That’s called a science coma, folks!

GRABER: I would not want to try this at home. But luckily he found what he thought would probably happen. When they ate, they slowed down even more.

KUKUSHKIN: They literally become sluggish. More sluggish than they normally are. They’re always sluggish, but they’re extra sluggish when you give them those, those chemicals.

TWILLEY: This one insulin-like molecule—Niko and his colleagues showed that it not only enhances memory, but it also helps the slugs digest glucose. And during that digestive process, they’re in the slug version of a food coma.

GRABER: So if you’re a sea slug, your gut makes a molecule that helps you digest food. But why would that same molecule make you slow down, and also help you remember things? Niko says, though, that it makes sense that this insulin-like molecule would be so powerful.

KUKUSHKIN: It’s not just to take in the nutrients from the food. It is simultaneously to take in those nutrients and to reallocate the energy into storage of memories. And what we sometimes forget is that memory is from the past, but it is for the future. The point of memory is to change the behavior in the future. So, if we approach it from that standpoint, then it makes sense that the goal of creating this food coma would be to enhance the events that led to it. And make them more likely to happen again. You found some food, you want to remember where you found it. You want to store the state of your brain for later, and access it in the future. Find more of that food. So it makes sense to slow down, stop exploring. Invest that energy that you’ve just acquired into forming a memory.

TWILLEY: This is a very elegant theory. But there is a caveat. Niko doesn’t yet know whether the memory that is being strengthened by that food coma molecule is a memory about food. It could be a memory about a particularly attractive fellow sea slug.

GRABER: This seems like it would be really hard to test, but Niko told us that sea slugs find their food by the chemical traces in the water, kind of like smells. And so in theory they would test if a sea slug was quicker to find a similar meal the next time. Quicker is relative, of course.

KUKUSHKIN: We haven’t done that study, but I think it’s a reasonable thing to ask. After consuming a certain type of meal, would the sea slug become more sensitive to that particular food and seek it out more efficiently than another type of food?

TWILLEY: But also not to be totally anthropocentric here, but does finding out what triggers a food coma in a sea slug have any relevance to humans?

KUKUSHKIN: The short answer is we don’t know. We know that we have related molecules.

GRABER: We have related molecules, but they’re slightly different. Over the course of the millions of years of evolution that separate us from our sea slug cousins, we’ve developed a couple of different hormones that are released after we eat that mimic what the insulin-like hormone does in the sea slug.

KUKUSHKIN: And so what works in the sea slug… will not necessarily work the same way in a human.

TWILLEY: But Niko says that it is also possible that this ancient connection between digestion and memory is still functional in humans

KUKUSHKIN: It’s possible that it’s a vestige of something that used to have a functional purpose and no longer does. But, evolution is pretty smart. And usually if there was something that didn’t help us, that purely slowed us down, with—without any flipside to it, evolution would have probably gotten rid of it over millions of years. So I think it is very reasonable to assume that if we so consistently get tired and fatigued after a meal that there’s something useful about it. We can’t always make that assumption, but I think it’s a pretty reasonable hypothesis.

GRABER: This is all super interesting and might just be the answer to why we get a food coma. But one thing is bothering me: Justine and Subha’s study showed that the kids were doing worse on tests after they ate, when they felt tired. If their memory was being enhanced by the meal, surely they’d be doing better?

TWILLEY: When we asked Niko about this, he said Justine and Subha’s results actually makes sense: because if those post-meal digesting students are using their cognitive resources to strengthen a memory, those resources wouldn’t be as available for other cognitive challenges like reading a paragraph. Their brain is otherwise occupied.

GRABER: Niko and Justine and Subha say we have most definitely not solved all the mysteries around food comas, but these are some intriguing studies, and at least, Laura, we know that you’re not just being lazy! Food comas are real.

TWILLEY: But so is a dessert stomach, and so I am guessing we all still have room for one more mystery this episode: what up with ranch? That story after the break.

[BREAK]

GRABER: We’ve had two courses so far in this listener-inspired episode, and now, finally, for dessert, you guessed it: you get some ranch dressing!

ABBY REISNER: There were a few people who were experimenting with ranch ice cream. I thought that a ranch birthday cake could work, because buttermilk, and frosting. Doesn’t quite work, I would say.

TWILLEY: Abby Reisner is the author of Ranch: An Ode to America’s Beloved Sauce. And she loves ranch, unsurprisingly.

GRABER: Our listener Josh is the one who asked us to investigate this pressing topic, and he has also seen the dessert connection.

JOSH: As a middle school assistant principal, I see kids dip all kinds of things in ranch dressing, not just put it on their salads. I’ve seen things like pickles, and cookies, and… I mean, it’s, it’s like, gross actually, but fascinating at the same time.

TWILLEY: Josh wanted to know what on earth is going on with this ranch on everything trend. But I’m actually coming at this with a much more basic question: what is it? As you listeners will know, I’m British and I grew up in England and the dressings that you could buy in bottles when I was kid were blue cheese, italian, thousand island, and of course that British speciality, salad cream. Which is like a weird, pourable mayo? Ranch was not a thing.

GRABER: I’m obviously American, I grew up here, and Nicky we overlapped on everything but that odd sounding salad cream. We did, though, have access to plenty of ranch. But I didn’t spend a lot of time reading the ingredient list.

REISNER: Well, at its core, ranch dressing is some dairy—you know, that could be buttermilk, it could be sour cream, it could be coconut milk, you could make a vegan ranch. Or any combination thereof. And mayonnaise, often. And then herbs and spices. So a combination of dried herbs, and that can really vary by, by the chef, or by whoever is in charge of Hidden Valley. And often dried onion. Dried dill. Some really pungent things. And that really contrasts the cooling nature of all the dairy.

TWILLEY: OK, that gives me some sense of what we’re dealing with here. But I also asked Abby for some tasting notes, just to help me get in the ranch headspace.

REISNER: I would say it’s almost a—a parabola of an experience. The first thing you get is really the creamy coating of your mouth. And then you get the spices, the alliums of it all. And then afterwards, the dairy comes back in.

GRABER: So Nicky, you might never have tasted ranch before, but Abby says you’ve probably tried some of its culinary cousins from around the world.

REISNER: The basic combination of this, we see it all over the place. There’s a Polish white, creamy dairy sauce. There’s aioli that people know. I think every—not, not every culture, but a lot of cultures across the world have something that’s very similar. So I think it’s a situation of: same good core idea manifesting in different ways across the world.

TWILLEY: Lovely, now I have a handle on the basics, so let’s get into this. Who manifested ranch?

REISNER: So it was a guy named Steve Henson. He went up to Alaska. He was a plumber. We’re talking 1940s, 1950s.

GRABER: At the time, contractors in Alaska made a lot of money, that’s what Steve went up there for. And he also occasionally served as a cook for construction crews.

TWILLEY: Veggies weren’t necessarily super fresh on job sites out there, and so Steve would attempt to make them more appetizing with a creamy, herby dressing. But there weren’t a lot of fresh herbs either, so he used dried.

REISNER: And then after making it big in Alaska as a plumber, he said, you know, what I really want is to own a ranch in Santa Barbara. So he moved just outside of Santa Barbara, bought a place. It was originally called Sweetwater Ranch. He renamed it Hidden Valley, which you know, is where we get, eventually, to the Hidden Valley of today.

GRABER: At their California Hidden Valley ranch, he and his wife Gayle opened a restaurant. It was kind of a restaurant night club combo, there wasn’t much around there, in the evenings Gayle would play the organ for entertainment.

TWILLEY: The food was pretty basic, sort of steakhouse fare. And everything came served with Steve’s house dressing.

REISNER: There was an account from both his son and then also someone who had worked and lived at the ranch for a while, and they said it was really very popular served on the steak and on potatoes. Sometimes with the vegetables as well.

GRABER: That ranch dressing—that’s what he called it—the dressing itself was probably *the* most popular food Steve made. People started taking it home in jars. Another nearby restaurant started serving it, too.

TWILLEY: Eventually Steve realized that more people wanted this dressing than he could sell it to in liquid form, so he made a mix of dried herbs and onions and garlic, so people could recreate it at home.

REISNER: He ended up doing a mail-order product of the little ranch packet. And for, you know, I think less than a dollar or so you could write in and get this packet mailed to you. And all you’d have to really do is mix it up with, you know, some, some mayo and some dairy, and it was like a cake mix, but for ranch dressing.

GRABER: The mail-order ranch packet business ballooned, and it eclipsed the steakhouse dude ranch. They shut everything down so they could fulfill orders. And then big business came calling.

REISNER: In the 70s, it was bought by Clorox for $8 million. And was really—had a lot of advertising behind it at that point. And I think that’s what really got it out to the masses. I don’t think that Steve Henson’s mail-order business would have been long term sustainable enough to really popularize it. But it is funny to me to think that, of all things, it was Clorox that bought it. It’s just not an association I would put in my head.

TWILLEY: This is also confusing to me. Clorox I associate with cleaning the bathroom, not with making a salad. But it turns out that at the time, Clorox had recently been spun out of its parent company, Proctor & Gamble, and they were on a mission to copy the very successful P&G playbook

GRABER: P&G owns a ridiculous number of brands—today none of them are food brands, but back in the ‘70s they owned a lot of food companies, ones like Folger’s coffee and Jif peanut butter. And Clorox thought they should get in the food game too.

TWILLEY: Weirdly, they pretty much stopped after ranch, but anyway, that was the business thinking at the time.

GRABER: And as Abby said, Clorox threw a bunch of money into advertising their new product.

REISNER: It’s comical almost. Slow motion videos of young girls walking their cows through the fields. And someone squeezing Hidden Valley Ranch onto a single stalk of broccoli and then biting down.

WOMAN: Hidden Valley ranch: how could anything so fresh and delicious come from anywhere else? True, not everyone can live in Hidden Valley, but you sure can get a taste of it.

REISNER: There really was some hefty marketing budget behind it. And it was kind of, you know, it was phrased as a healthy alternative to blue cheese originally. Whether or not that’s true.

TWILLEY: It was also positioned as sneaky secret ingredient behind homemade deliciousness.

WOMAN: Terrific salad.

MAN: Especially the dressing.

WOMAN: Ever gonna tell us how you get this special taste?

GRANNY: Got a secret recipe!

VOICEOVER: Hidden Valley Ranch. Nobody else has our secret recipe! Nobody else has our special taste.

GRABER: Packet salad dressing wasn’t unusual at the time, you could even find packets of Italian dressing herbs and spices that you’d mix with oil and vinegar. But you could also find bottles of fully made salad dressing on the shelves. The problem with ranch was the dairy.

TWILLEY: But by 1983, the whiz kids at Clorox had figured out how to make the buttermilk component of ranch shelf-stable too, and bottles of Hidden Valley ranch dressing hit the shelves.

GRABER: And ranch’s popularity skyrocketed.

TWILLEY: At this point, ranch dressing was popular enough that Kraft and other companies had introduced their own versions, to compete with Hidden Valley. But ranch really got a boost in 1986 when it transcended the dressing sector and became a … chip flavor.

VOICEOVER: Introducing new Cool Ranch flavored Doritos! A creamy blend of tangy spices and cheese flavor.

[CRUNCH, MAN FALLS]

REISNER: It’s a little before my time, but I think about my older siblings, and to them, that’s just such a part of the late ‘80s and early ‘90s. It’s just fun, and you’ve got people eating it in lunch rooms, and it just becomes a core memory for people that grew up during that time. Further cementing the ranch flavor as more of a thing, rather than just ranch dressing.

GRABER: A few years later, in 1992, ranch reached another milestone: it became THE most popular salad dressing in America.

REISNER: The nineties, that’s when, to me, a few things happened. You’ve got Cool Ranch Doritos taking on a cultural phenomenon. You’ve got Domino’s. It’s, it’s believed that Domino’s pizza spearheaded the wedding of pizza and ranch. They were selling ranch with their chicken wings, and found that people were actually dipping their pizza into it.

TWILLEY: The 90s were good for ranch, but the 2000s, and 2010s—that’s when ranch truly exploded, so to speak. At one end of the spectrum, you had McDonalds and Taco Bell serving ranch as a sauce for fries and nuggets and nachos. But at the same time, high end chefs were embracing it and making their own haute cuisine versions.

GRABER: There’s a famous Chicago restaurant called Alinea. The chef is Grant Achatz, and they served their own particular high end version of a salad with ranch.

REISNER: And I think it really was truly a leaf on top of some dressing sprinkled with ranch powder, which is just kind of funny. That is about as high as you can raise ranch.

TWILLEY: And then ranch started showing up in pop culture.

REISNER: You have Melissa McCarthy dowsing herself with Hidden Valley Ranch on SNL.

PRODUCT TESTER: Okay. The products we’re going to be testing today is a new line of dressing from Hidden Valley Ranch.

MELISSA MCCARTHY: Awesome. Woo! Awesome! Hidden Valley Ranch!

GRABER: In the skit, Melissa McCarthy is one of three taste testers. She’s wearing a sweatshirt with Spock’s face on it and she’s clearly already a huge ranch fan, she keeps whooping and cheering.

MCCARTHY: There’s a Hidden Valley Ranch party in my mouth! [AUDIENCE LAUGH] There’s a Hidden Valley Ranch party in my mouth. Write that down for your—there’s a Hidden Valley Ranch party in my mouth!

TWILLEY: Homer Simpson is another pop culture ranch superfan. He would rather have ranch than belly dancers.

HOMER SIMPSON: Enough! I grow weary of your sexually suggestive dancing. Bring me my ranch dressing hose! [CLAP]

[HOSE STARTS, HOMER GURGLING]

GRABER: Hidden Valley really leaned into all of this. They made a ranch dressing keg, they made a special bottle for Megan Markle and Prince Harry’s wedding.

REISNER: I think around 2017 or so you start to see some really, out there ranch merchandise. You have sapphire and diamond encrusted bottles. You have ranch Christmas ornaments, even. Something very simple, but just taking over everywhere and really getting ranch top of mind for people, and these kinds of novelty gifts.

TWILLEY: Abby was always a ranch lover herself, but in writing her cookbook, she ended up going really deep into ranch culture.

REISNER: I watched a video that I’d like to unsee, but it was someone taking a literal bath in ranch dressing and putting it on TikTok.

GRABER: Abby does not suggest in her cookbook that you bathe in ranch, which I do appreciate. But she does have a whole variety of recipes: there’s ranch biscuits, ranch grilled cheese, ranch arancini, a ranch frittata, and of course, a recipe for homemade ranch powder itself.

TWILLEY: Which you can use to make homemade ranch Doritos.

REISNER: Well, I do love the homemade Cool Ranch Doritos. They take a little bit of time because you have to fry tortillas, but it is an amazing party trick to pull out. I made them for co-workers six years ago at this point, and they still talk about it to this day.

GRABER: Ranch’s popularity isn’t a thing of the past, we’re still riding that wave. It’s the thing that Josh’s middle school students dip pickles and cookies in, you can still find it in all sorts of restaurants, and it’s still the number one salad dressing in America.

TWILLEY: But to Abby, ranch dressing is more than just a delicious salad dressing and dip—it is the ultimate American food.

REISNER: My favorite fun little thing to think about with Cool Ranch Doritos is how everywhere else in the world it’s called Cool American, because that is equating ranch with America.

GRABER: To Abby, it’s not just that Europeans see ranch as equivalent to America, but also ranch as a story, that’s what makes it really American.

REISNER: Maybe this is a little philosophical. But to me, it comes down to its origin story and how it’s coming from a man who really… did the American dream. And, you know, it then goes into capitalism and all this. And to me, everything that ranch has been through is a very American story. So, not just, is it paired with foods that are also typically consumed by a high number of Americans—like pizza, like chicken wings. But it’s the backstory of it all. That it really fought for its life out there. And it, and it came out being purchased by billionaires.

[MUSIC]

TWILLEY: Thanks this episode to Abby Reisner, Frank Maixner, Justine Herve, Subha Mani, and Nikolay Kukushkin, whose research was conducted at the Carew lab. We have links to their research and books on our website, gastropod.com. And thanks of course to all you delightful listeners who wrote in with fascinating questions.

GRABER: Thanks as always to our amazing producer Claudia Geib. This is our last episode of 2024. We hope you all have a wonderful end of the year, and we’ll see you in 2025!