So Hot Right Now: Why We Love the Chile Pepper

0:00it's incredible this is you on Carolina reaper pepper it just keeps giving and giving I was 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.

0:56But 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.

1:30We, 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?

2:06The 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 encore episode was made possible thanks to generous support from the Alfred P. Sloan Foundation for the Public Understanding of Science, Technology and Economics, as well as the Burroughs Welcome Fund for our coverage of biomedical research.

2:44Gastropod is part of the Vox Media Podcast Network. Support for the show comes from Google Gemini. You know that moment when curiosity strikes? You're exploring a new city with the family and a sculpture catches your daughter's eye. What is that? Who made it? With Gemini, you can snap a picture and get a fully interactive breakdown of its history, architecture, and even hidden secrets. Gemini is built for moments like that. Whether you're learning something new, solving a problem, or looking for your next favorite thing, Google Gemini is here to help. Download Gemini, Google's AI app, or visit gemini.google.com to learn more.

3:28Hey Chicago, class it up with Crocs You know back to school is coming in fast So why wait to find your new fave footwear Step into a local Crocs store and step into your new look Try it, style it, make it yours Because the right pair doesn't just show up, it shows off First day fits, handled Walk out ready for whatever's next Visit your nearest croc store today. This might sound like a just-so story, but why is the chili pepper hot? To answer that, we spoke to Maricel Precia. 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.

4:15So 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.

4:51Birds 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 it grows into a new plant. Whereas us mammals, we can feel the heat and it passes through our digestive system. And actually our system destroys the seeds so it can't grow into a new plant.

5:30And 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.

6:09And 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, star of our recent Smoke episode, 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.

6:56And 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 galleries 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.

7:33But 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.

8:14And 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 lived nearby the site preparing food from corn, root vegetables, shellfish, and not much else. So it struck me that what elevated this type of cooking from subsistence rations to a true cuisine was the skill use of peppers. So the local ajis that I had seen women crushing into sauces. These chili peppers, they're called aji locally. Maricel says they're doing two different things.

8:49They 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.

9:25But 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 Huaca Prieta.

10:06Maricel told us that Huaca Prieta was first excavated in 1946 by an archaeologist from the American Museum of Natural History. And they started excavating this mound. 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 Huaca Prieta. So the archaeologists took samples of the fossilized poop. They had it analyzed using the new technique at the time of carbon-14 dating to get a better read on how old it was.

10:51But 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 7 ,500 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 anion, which is believed to have been domesticated in what is today Mexico.

11:30So 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 bacatum, which you mostly find in Peru.

12:08And then there's number four, frutescens, which Marisol 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 pubescence, and this one we almost never eat in the U.S. or Europe because it doesn't dry well, and so mostly people eat it fresh in South America, or it gets shipped frozen, and you might find it under the name rocoto or locoto in Latin American restaurants. 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.

12:44We had eight different dried chili peppers lined up in front of us. It wasn't the season for fresh. we decided to start with a teppin it's an annum 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 do 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 absolutely 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.

13:46It 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.

14:32heat that's above 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 somatic sensation, they experience many different kinds of injuries, sometimes fatal ones, because they simply have no ability to sense pain.

15:09Pam Dalton has been on the show before. She's 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 tapene, it felt like the very follicles on my head were starting to sweat.

15:46I 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.

16:24Your 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.

17:06It's white and a little crystalline, yes. Powdery, but a little flaky too as well. After that tapene, 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, you know, essentially cause reflex apnea.

17:50You 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 Carolina Reaper from their co-host and supposed friend. And actually, people in South and Central America used chilies in war. They'd make grenades with ground chilies in them and launch them at 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.

18:24Cynthia was taking notes, clearly. I don't know how to defend myself here, I promise. I don't have a vendetta against Nikki I've been keeping secret all these years. 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.

19:02And 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? Coming up after the break.

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22:43So 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.

23:18One 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.

23:55That'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 it's, unless it's, you know, 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, you know, cortical effect or relief of, you know, sort of anxiety about it.

24:40I 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 tippin, 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.

25:20For 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. Ooh, 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.

26:03It'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, 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 a 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 good. It's warm. It dissipates pretty quickly. Like I'm not left with this lingering burn.