Science Vs - Presenting Gastropod: How Chilis Conquered the World

Episode Date: November 25, 2021

This week we’ve got a spicy treat for you: a show called Gastropod. Hosts Nicola Twilley and Cynthia Graber dig into the world of food and serve up a forkful of science, plus a dash of history. In this episode: chili peppers! Why do we love spicy things when they set our mouths on fire? Plus, where did chilis come from — and how did they take over the world? Find more Gastropod here: https://gastropod.com/ Gastropod thanks: the Somerville, Mass., store Christina’s Spices, which ships all around the country—they have the best selection of chiles Cynthia has found anywhere online, even compared to places that specialize in chiles. 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. Thanks also to Maricel Presilla, Danise Coon, Harold McGee, Pam Dalton, and Edward Wang.  Science Vs is hosted and executive produced by Wendy Zukerman; our producers are Michelle Dang, Rose Rimler, Meryl Horn and Ekedi Fausther-Keeys. Editing by Blythe Terrell. Mix and sound design by Bumi Hidaka. Music by Peter Leonard, Emma Munger and Bobby Lord. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hi, I'm Wendy Zuckerman and you're listening to Science Versus from Gimlet. This week, we're serving up a special spicy treat for you. We're sharing an episode from the podcast Gastropod. It's hosted by two food nerds, Nicola Twilley and Cynthia Graber. And over at Gastropod, they spend their time exploring food and science and history. In this episode, they are slicing and dicing the chili pepper, trying to find out why we love this thing that sets our mouths on fire. And also, where did chilies come from? And how did they manage to conquer the world of food?

Gastropod is coming up just after the break. It's season three of The Joy of Why, and I still have a lot of questions. Like, what is this thing we call time? Why does altruism exist? And where is Jan 11? I'm here, astrophysicist and co-host, ready for anything. That's right. I'm bringing in the A-team.

So brace yourselves. Get ready to learn. I'm Jan right. I'm bringing in the A-team. So brace yourselves. Get ready to learn. I'm Jana Levin. I'm Steve Strogatz. And this is Quantum Magazine's podcast, The Joy of Why. New episodes drop every other Thursday, starting February 1st. What does the AI revolution mean for jobs, for getting things done. Who are the people creating this technology? And what do they think? I'm Rana El-Khelyoubi, an AI scientist, entrepreneur, investor, and now host of the new podcast, Pioneers of AI. Think of it as your guide for all things AI,

with the most human issues at the center. Join me every Wednesday for Pioneers of AI. And don't forget to subscribe wherever you tune in. It's incredible. This is you on Carolina Reaper Pepper, huh? I know. It just keeps... It keeps giving and giving. It's just like, oh, no. Anyway, I was just like, can you imagine if I rubbed my eyes? I'd be in the emergency room.

Oh, dear. Anyway, kids, don't try Carolina Reaper at home. Do not. Do not even open the jar. Do not even have a friend ship you the jar. I promise I was not trying to unleash a chemical bomb on Nikki and her husband, Jeff. The lid to the jar of Carolina Reaper chili powder apparently came off in the mail. She was coughing throughout our entire next recording session. 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.

I do still feel bad about it. I mean, the guy who sold me all the chilies 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. I do literally know how he feels, sadly. Yes, this episode, we are deliberately subjecting ourselves to the chili pepper burn. And not just any chili pepper burn, but the hottest chili pepper in the world. 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. And I'm Nicola Twilley. And normally, I really like chili peppers. I have lots of different dried ones in my spice cabinet and all kinds of fun fermented hot sauces, chili crisps, salsa matcha in my fridge. So I was looking forward to this episode. Unsurprisingly, I have pretty much the same setup in my kitchen as Nikki 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? The chili is botanically a berry, for heaven's sake. Why is it so hot and

spicy rather than just sweet and fruity? How did this rather assertive berry spread from its home in South America and conquer, well, almost the entire world? To the point where I can't even imagine Indian or Chinese or Nigerian food without it. And why was the U.S. and Northern Europe so slow to catch on? All that plus the rise of the superhots. Is there a limit or will chilies finally actually kill us? This might sound like a just-so story, but why is the chili pepper hot? To answer that, we spoke to Maricel Prasia. She's a chef and a culinary historian, and she wrote an incredibly beautiful book called Peppers of the Americas, which traces chili peppers all the way back to their South American origins. So the forebears of today's peppers and tomatoes split off from a common ancestor about 20 million years ago in South America.

Maricel says back then, millions of years ago, peppers looked and smelled like a tasty snack to the animals in the region. Which was a problem because the chili peppers' precious seeds would get destroyed in most animal guts and chili peppers want to have baby chili peppers. And so chilies developed a defense strategy. 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. 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. Joining the chili chorus is Denise Kuhn.

She's a chili pepper researcher at New Mexico State University, home to the one and only Chili Pepper Institute. And so they can eat lots and lots of these tiny hot little berries and pass it through their digestive system unarmed and 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 chili pepper plant evolved capsaicin was to keep mammals from eating them. But then look at what we go and do.

Denise told us chili peppers are the only plants in the world that produce capsaicin. And because chilies are making capsaicin to protect their precious seeds, they put most of that protection right around those seeds. And if you cut a 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 chili plants is found in that supporting material in the placenta. Listen up. This is Harold McGee, author of Nosedive 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 chili pepper is in the seeds, but he says no, it's mostly in the white placenta stuff. 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 chilies have been dried. So this is why and where chilies are spicy.

But if the point was to put us off from eating them, then why did early humans in what's now Peru and Bolivia give them a try? Prehistoric hunter-gatherers must have been curious about these beautiful scarlet pots, and they experimented with the specimens that they found close to their own settlements. 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. 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. 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. And Maricel thinks there was another reason that early humans in South America were so attracted to peppers. She visited the archaeologist's 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. So it struck me that what elevated, you know, this type of cooking from subsistence rations to a troupe we've seen was the skilled use of peppers. So the local ajillas that I had seen women crushing into sauces. These chili peppers, they're called ají locally. Maricel says they're doing two different things.

They make the 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 chilies make starchy foods less boring to eat and easier to digest. Honestly, the pep from the heat, in addition to all the great flavors in chilies, that spice can kind of make food more exciting. It really does literally add some zinc. I mean, how many terrible sandwiches and on-the-road breakfasts have you rescued with some hot sauce?

All of them. 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. 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 dark colored mound called Huacaprieta. Maricel told us that Huacap Prieta was first excavated in 1946 by an archaeologist from the American Museum of Natural History. And they started excavating this mount. They found 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 jewels, because organic matter is very difficult to combine. But there was plenty of it at Huacaprieta. 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 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. 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. Probably then and still today, there are around 30 species of wild peppers. At some point around the time the El Brujo people were eating chilies, or since then, nobody really knows, we domesticated five species that we still enjoy today. Now the most important of these species is Capsicum annum, 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. Maricel compares the five domesticated chili pepper species to the five alliums, garlic, chives, onions, leeks, and shallots in terms of how different they can be in their flavor personalities. Anam is the most common domesticated chili, and so, unsurprisingly, it's the most diverse. Basically, all the dozens of peppers you might eat in Mexico are anams. Jalapenos, poblanos, bell peppers, all anam. Then there's chinense, of which the most famous is probably habanero.

Number three is picatam, which you mostly find in Peru. And then there's number four, frutescens, which Maricel says is the most one note of the chili pepper family. It's just kind of sharp and hot. The most famous frutescens is Tabasco. 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, and you might find it under the name rocoto or locoto in Latin American restaurants. 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. We had eight different dried chili peppers lined up in front of us. It wasn't the season for fresh. We decided to start with the tapin. It's an anum. 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 the closest to the wild chili pepper. And because it was dried, we had to rehydrate a few with boiling water. So shall we try one? Yeah. Okay, here we go. Here we go. Oh my god. Oh my god. Why did we start with this? Oh, my God, Nikki. Why? Why? Why? I just, I had to just swallow it. Why?

I think my digestive tract is burning. You know that? Okay, so, Cynthia, I think it's good. Now I feel, like, really pretty good about having had the Reaper yesterday because this is nothing. This is nothing. Yes, it's spicy. Oh, my God, it's spicy. It has some nice flavors to it, but it's smoky.

It has some smokiness. It has some fruitiness. It's quite sharp. I swallowed that really quickly. I couldn't let it spend too much time in my mouth. I was trying to let it spend time in my mouth. And now I feel like that might have been a mistake. 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. 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. The capsaicin molecule is triggering a receptor in our mouths, or 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 water or tea in your mouth. It's part of something called the somatosensory system. 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. Pam Dalton is a scientist at the Monell Center in Philly, and she works with capsaicin in the lab.

Pam told us that we can, in fact, feel capsaicin anywhere on our body, as long as our skin isn't too tough. 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. No kidding. Another thing I noticed personally, after I ate that tapin, 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. 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. 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.

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. And this is one of the reasons, and of course, it's borne out by, you know, 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. Meanwhile, back in non-tropical Philly, Pam actually works with neat capsaicin in the lab. It's white and a little crystally, yes. Powdery, but a little flaky, too, as well. After that tapin, the powdered pure capsaicin sounds a little terrifying to me. We wondered if Pam ever tried it neat.

Of course. 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 form, 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. You 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. Or, you know, unpacking a shipment of attackers and leave their enemies basically choking and blind. Another tactic was to put the chilies in what were kind of like water balloons. So they'd ferment and then burst on impact, releasing all their noxious, painful gases.

Long story short, capsaicin is a powerful 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 chili grenade as a non-lethal but very effective weapon. But of course, as we've already said, the chili peppers burn is something that a lot of us find pleasant and exciting in somewhat smaller doses. 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 chilies.

And you can also train yourself to feel less heat just by eating hotter chilies regularly. Scientists think your receptors get less receptive if you're constantly feeling the burn. But what if you've accidentally gone a little too far in your chili pepper training regimen and the burn feels, well, really burny? What do you do? That answer and more from gastropod cynthia and nicola are walking us through the world of chili and when we left them they asked if you are feeling the burn what can you do about it food writer Food writer Harold McGee gave them an answer.

For the most part, the way you quench the burn of chili peppers is with time. So you quench it with suffering. You can 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. 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. 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. 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. 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. And if you want to combine all three, a milk product, lots of fat, and something really cold, I recommend ice cream. That's what worked for me after our tasting was done. What's more questionable in its efficacy is the classic accompaniment to a spicy curry, beer. Capsaicin is soluble in alcohol.

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. 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 cortical effect or relief of, you know, sort of anxiety about it. 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. After the tapin, we spooned yogurt all over our burning tongues and commiserated. 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 good for them. Good for them. 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. Capsicum chinense has cultivars all over, different colors, different shades, different levels of heat. For example, one of the favorite peppers of Peruvian cooks is something called aji panca. So we each opened up our jar of aji panca. Smells really good.

Oh, that's lovely. We shouldn't have done the other one first. No, because now I can't tell if this is spicy or not. Yeah. At the moment, it has no spice to me. I think it has a tiny bit of heat. I'm having a little more of this. It's really good. I'm starting to be able to taste again.

And it's nice. It was fruity, a tiny bit earthy, and it had just a little hint of heat. It was a really mild and lovely pepper. Staying in Peru, but with yet another different species of chili pepper, we moved on to aji amarillo. It's a bacatum. The aji amarillo is amarillo. It's definitely yellow.

It is indeed. It's very yellow. You're going to feel a little heat with this. This is one of my favorites. Okay. Oh my gosh gosh this tastes like peru to me while aji panca might be popular in peru aji amarillo is probably peru's national chili i had it on dishes all the time when i was traveling there it's really common in a sauce for

potato dish and also in ceviche i even had an aji amarillo ice cream there that i still dream about it's delicious it's rounded so. So good. It's warm. It dissipates pretty quickly. Like I'm not left with this lingering burn. No, that's true. I like it. This is my favorite so far by quite a long shot. So good. And finally, species number four. Capsicum frutensens. And just think of Tabasco. Tabasco sauce is made with capsicum frutensens. Very specific in terms of flavor and it's 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 frutensens know that it's fantastic for table sauces. Our frutescens. No, that is fantastic for table sauces.

Our frutescens chili that we'd bought was weary, weary. There are 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. So this is from Guiana. It's a staple spice from the South American region. So common that most Guianese kids grow up eating them.

Delicious tangy flavor, it says. Delicious tangy eating them delicious tangy flavor it says delicious tangy flavor delicious tangy flavor plus a lot of heat okay you just sing the kid stuff to make me feel like a wuss here but anyway oh my god oh wait i have to oh swallow it oh i don't think i can no oh i couldn't swallow it oh come on you have to swallow it i haven't tried yet i spit it out and swallowed just some of the seeds i have to to tell you, my head is sweating. Like, my scalp is sweating. My nose is running. Oh my god, Nikki, my mouth hurts so badly. Now my mouth hurts. I'm going to have some yogurt.

I'm like writhing standing here. Did you get a flavor? I didn't really get a... Oh god, my mouth hurts. What am I supposed to do? It hurts so much. Why won't the yogurt... Make it stop. Wow. Yeah, that was something. It's not really stopping. 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 chili take over the world? 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 a he with their food by the natives in the Caribbean. And so Columbus brought some of these precious berries back to Spain with him. 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. And when he landed in Spain, besides 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. And he wasn't wrong. Chili 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 chili peppers were a smash hit with all sectors of society. If you had a hot pepper plant growing in your garden, then you wouldn't have to spend a lot of money on pepper corns, which were very expensive. And there is a point that everybody was using it. You couldn't grow black pepper in your garden in Spain, but you could grow chili peppers pretty much anywhere.

And 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. Like the women Maricel saw using the aji to make a very Spartan diet into a delicious cuisine in Peru, Spanish peasants started relying on chili peppers to do the same thing. Chili peppers became so popular in Spain that the Spaniards even developed their own varieties, like the pimentón and padrón peppers. And every region, you know, has a different predilection for particular peppers. For example, if you go to the Rioja, is something called pimiento choricero, which translates as the pepper for chorizos, for sausages. Spain's neighbors, the Portuguese, also got into the chili pepper action early, and they were really the ones that spread chilies around the globe.

Portuguese sailors brought chilies to West Africa and to the Middle East and to Southeast Asia. The Portuguese brought peppers to India Middle East and to Southeast Asia. The Portuguese brought peppers to India, where they quickly became essential. Chili is central to the cuisines of Bhutan and Korea, but arguably the largest country that today is the most closely identified with the chili pepper among all the many nations that couldn't possibly imagine eating without chilies, I'd say maybe, probably, the winner is China. Like everywhere, the chili pepper first came into China through port cities, and it was quickly adopted, at least in certain regions. From the 17th century onward, then there was pretty systematic records about

the food people eat in these regions. Guizhou, Hunan, Hubei, and Sichuan were spicy. Edward Wang is head of the Asian Studies program at Rowan University, and he says those regions adopted chilies 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. And particularly that region lacks salt. So before chili peppers, they actually use vinegar to spice up their food.

That was one of the reasons that people use chili peppers, the taste of like hot, to replace the shortage of salt. The chili 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. And then in China, chilies were even more of a hit because of their color. That definitely has an impact because red is a festive color, right? So in weddings and New Year, major holidays,

people hang dried chili peppers at their doors. That definitely brings a certain type of happiness to their household. Yeah, that possibly also adds some reason to the popularity of chili peppers in those regions. So chili peppers were pretty inauspicious 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. So that's why initially that's why chili pepper was adopted as like a salt. Because if you

just eat the grain food, then it became, I mean, it was maybe too bland. So you need to have something else to consume them, right? And so in Chinese language, you have words like called xiafan means down the grain. Down the grain, like literally get it down you. So they will use chili peppers or salt or pickles to down the food. But in China, even among people who could afford more than just grains, chili spit into a certain way of thinking about food, a culinary style that valued combining lots of different tastes to make a meal. At one point in time,

Europeans ate richly spiced foods too, but by the time the chili 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. Chili 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. In China, though, spicy chilies became so deeply entrenched in some regions that many Chinese think the plant is native. Most of the people would answer that,

well, that's from Sichuan, from Hunan. They would consider it just like the tomato, right? Tomato, people wouldn't think that it was like from the Americas. So it was so become, I mean, so adopted into the Chinese cooking. Chili peppers have become entwined with Chinese identity. They show up in poetry

and slang. They embody all sorts of positive qualities. Hot tempered and courage, manhood, maybe masculinity. For girls, you have a term called a la-maids. La means spicy. And la-maids is also, I would say it's pretty positive to describe a woman who is more kind of adventurous

and not shy, not like a 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, right? And those are all, I would say, mostly positive images. There was no negative associations with eating chili peppers. And even in regions of China that had a tradition of blander foods that didn't adopt the chili pepper originally, well, today they're getting

spicy too. In the 60s, I mean, in the 1960s, 70s, when I grew up, chili peppers were not that popular among certain regions. They might be popular in Sichuan, in southwestern regions, like Guizhou, like Hunan, those provinces. And we know that these people love spicy food. But now, of course, my relatives, my friends in Shanghai are becoming addicts to spicy food. This is why my interest became inspired. I would say why over the last 30 years, spicy food has become so popular. 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 chilies to get the grain down moved to richer cities to work, and they brought their peppers with them.

And now, of course, even in Guangdong, Guangdong's cooking was very mild, I would say. They emphasized on 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. 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. Honestly, in general, the North American chili scene was pretty mild. Don't comment me Texans with your chili queens, etc. I'm talking in general compared to, say, China or south of the border in Mexico. The U.S. was just not especially spicy. That's been changing. In 2004, hot sauce and salsa finally conquered ketchup, mustard, and mayonnaise to become the very two top condiments sold in the U.S. Congrats, America. Good job. And you know, America, we're in it to win it. All those lovely chili peppers developed elsewhere in the world are nice, but we want the hottest of them all. Speak for yourself. I am not part of that we.

I'm channeling the chili heads, and there are a lot of them out there. You are embarking on a culinary journey. I love the pain of spicy food. That will probably not rest well with you. It awakens the soul. It's hell night, baby. 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. which means Bhutanese pepper in the local language. It is a mix of a frutescens and a chinense, and it had been growing in Assam and 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. Denise is a breeder at the Chili Pepper Institute, as we mentioned, and she pays very close attention to what people want to eat. And then 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 chilies. And it blows my mind because I prefer flavor. And when it gets to like one million Scoville heat units, it's nothing but pain. And you don't care what it tastes like at that point. Just as a point of reference, that Weary Weary that set our mouths on fire was about 225,000 Scoville. And a jalapeno maxes out at a puny 8,000 Scoville. But what do those thousands even mean? Where does the Scoville thing come from? 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 give people an understanding of how hot chili peppers were.

So he set up a human subject 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. So if you had to dilute the chili pepper solution 5,000 times before you couldn't feel the burn, you'd end up with a pepper that was rated at 5,000 Scoville units.

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. But there's a larger issue that Pam pointed out, desensitization. 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 experience as before. And so you can do some pretty interesting challenges with people if you kind of pregame 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. 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. 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. Even though today, scientists like Denise 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.

Because Scoville units are what the chili heads are chasing. Before the 1990s, there were only a couple of known chili peppers that were rated above 300,000 Scoville heat units, the Scotch Bonnet and the Habanero. But now the Guinness 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 superhots. And it all started when Denise's colleague at New Mexico State collected the butchulochia or ghost pepper near Assam in India and brought it back to test and study it. Turns out superhot peppers are botanically different from regular peppers. The capsaicin isn't confined to just the white placenta stuff. 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 chilies and produce a lot of capsaicin. So that's the biology of the super hotshots are really, really hot chilies and produce a lot of capsaicin. 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. Yeah, so the hottest anything can be is actually 16 million Scoville heat units, and that's pure capsaicin.

But actual chili 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. 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. Because chili heads love it. And they are also in a competition for who can eat the spiciest pepper of all. Come on down. I salivate for hot food. We create some of the hottest food in the world. Hot food, please. Okay, but a weary weary 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? 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 roller coaster 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.

Unsurprisingly to me, chili competitions tend to be a kind of chest-beating macho type thing, not my speed. 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-chili vomiting. Another reason to skip the chili head competition. But unfortunately, Nikki and I had our own tasting to do, and the Weary Weary 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 Nikki. Are you ready? Will I ever be ready? Do you have some? I have some. I'm going to just take the tiniest bit on tiny bit of my tongue okay are you ready yeah one three two two one now before our big reveal we were warned by the owner of christina'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 weary

weary or rather spitting it out, I wasn't taking any chances. I wanted to minimize the coming pain. After inhaling it the day before, I too was a little weary. I took like a forensically tiny amount on my pinky and put it in my mouth. Oh! Okay. It just... Like it's... My throat hurts. At first I first i was like there's nothing and now there's

and i'm not putting the rest of what's on my um my finger into my mouth because i'm i touched my finger to my lips on the way out and that is burning like i did not do that and i'm not going to don't i think i'm gonna rinse my finger you're smart you're a smart lady oh but but it does hurt my throat my throat hurts my nose is running we went and washed our hands and ate some yogurt and coughed and blew our noses my mouth hurts really badly it really hurts like it actually hurts still yeah. Still. Yeah, it's pain. No, like, it's like serious pain in my mouth. I mean, this Carolina Reaper, I'm never going to touch this Carolina Reaper again. I don't know why it even exists. It's horrible.

This pain went on for many minutes. Why is it still burning? Okay, this is, I'm just going to go spin some yogurt into my mouth for a while. I'm going to go lie down. Okay, bye. Bye. That was bye. Bye. That was Gastropod. If you love food, science, and history, you've got to tune in.

We'll be back next week with Science Versus. And for full credits of this episode of Gastropod, and to find out where you can buy those very spicy chilies, check out our show notes. I'm Wendy Zuckerman. Back to you next time.