A pleasure to burn: Why do people like spicy foods?
Spicy foods are enjoyed the world over, but scientists don't know why people partake in culinary masochism.
- Humans are the only animals known to willingly eat foods that cause irritation, discomfort, and even pain.
- Theories for why range from thrill-seeking behavior to an evolutionary adaptation for seeking foods that reduce pathogens.
- Taste results from an interplay of genes, culture, memory, and personality, a complex design that scientists are only now beginning to understand.
If a Martian anthropologist found its way to a Clifton Chili Club Chili Eating Contest, it would discover one the universe's true oddities. Here, it would witness a group of bipedal primates cheering on other primates as they torture themselves with fruits that set their mouths on simulated fire.
By extraterrestrial standards, the rules are simple. The competition asks participants to nosh a chili pepper to the stalk. If they quit, throw up, or drink a glass of milk — which sits before them with tantalizing temptation — they are disqualified. Each round introduces a new pepper of increasing "pungency," that burning heat as measured by the Scoville scale.
Things start easily enough with the dainty Padron pepper, which averages around 500 Scoville heat units (SHU). By round 3, participants enjoy a classic jalapeno (3,000-6,000 SHU). Round 9 introduces the habanero (300,000 SHU). At this point, most participants are suffering inflamed eyes and molten saliva draining into their eruptively churning stomachs. The culling has begun.
In the final round, three competitors squared off against the Carolina reaper, the world's hottest chili. Averaging 1,641,183 SHU, it is more than 250 times hotter than a jalapeno.
Which leads our Martian anthropologist to ask, why? Even setting aside the extremes of a chili eating contest, why do people all over the world enjoy spicy foods or any food that causes pain and irritation? What is going on with these funny Earth animals?
Capsaicin is for the birds
A marine undergoes pepper spray training. The ingredient that gives pepper spray its debilitating sting, capsaicin, is the same ingredient that gives chilies their beloved fire. Image source: Cpl. Neysa Huertas Quinones/U.S.A Marine Corp
The truth is scientists — human scientists, that is — don't know how people acquired a taste for tortuous cuisine. They're not even sure why peppers began to sport capsaicin, the molecular compound that triggers your tongue's pain sensors, in the first place.
Some evidence suggests that pepper plants use capsaicin as a mammalian repellent. That may seem odd, as most plants try to entice animals to spread their seeds with sweet flesh and enticing colors — not detract them with promises of a seared tongue.
But mammals' strong stomach acids break down pepper seeds, reducing the plants' fecundity. Birds' digestive tracts, on the other hand, allow the seeds to pass through unharmed and be dispersed widely. Not coincidentally, birds aren't sensitive to capsaicin. Their taste receptors don't register its pungency.
There is also evidence that capsaicin is a natural antifungal. Studies have shown that pepper plants in fungal-rich environments produce more of the compound than those from drier environments.
Both theories explain the evolutionary advantages capsaicin provides the pepper planet. We simply don't know which one, or perhaps another, was the impetus for the pepper plant to favor capsaicin-fueled fruit.
Those who favor fire
The world's hottest pepper, the Carolina reaper, features a warning red color and a malicious looking spike, practically daring thrill seekers to give it a go. Photo credit: Wikimedia Commons
Getting back to people, there are several vying theories as to how humans developed a taste for pain. One is that we simply enjoy the thrill of it. Dr. Paul Rozin, professor of psychology at the University of Pennsylvania, argues that people use spicy foods as a type of "constrained risk" or "benign masochism."
Eating spicy foods triggers a mild defense response in us. Our heart rates rise, our breathing increases, and our adrenaline starts to flow. We feel alive. It's the same thrill-seeking behavior exhibited by bungee jumping, roller coasters, and horror movies. The thrill of pain rejuvenates us, while we secretly know all will be well in the end.
The Eastnor Castle Chili Festival Chili Eating Contest seems to support Rozin's theory. While some people can get a thrill out of a roller coaster, others need to jump off a bridge with a literal lifeline tied to their legs. Similarly, while some people can get a jolt from a jalapeno or habanero, others require the Carolina reaper to jump start their heart. And as we desensitize ourselves to one thrill, a more extreme one must then take its place as evinced by the eternal quest for an ever-hotter pepper or mouth-melting hot sauce.
Add to that the sense of camaraderie and community that naturally comes with food, and our Martian anthropologist may yet understand the ritual.
"Humans and only humans get to enjoy events that are innately negative, that produce emotions or feelings that we are programmed to avoid when we come to realize that they are actually not threats," Rozin told the New York Times. "Mind over body. My body thinks I'm in trouble, but I know I'm not."
Further supporting Rozin's theory is that all other mammals avoid spicy, painful foods. In fact, we know of only one other mammal that shares a taste for peppers: the Chinese tree shrew. But tree shrews aren't nature's chili-heads. It has instead evolved taste receptors that makes it less sensitive to capsaicin, thus expanding its food options. In other words, the shrew doesn't take pleasure in a smoldering snack like we do.
An acquired taste
A spice seller in Luxor, Egypt. A survey of traditional recipes show that spices are used extensively in the cuisine from cultures in tropical climes. (Photo: Tour d'Afrique / Flickr)
Another theory points to spicy foods' antifungal and antibacterial properties. In this light, humans have culturally and genetically evolved a preference for spicy foods because they protect us from microscopic assailants. When our taste buds encounter pungency, it's a signal to our brains that the food is cleaner.
A report published in the Quarterly Review of Biology looked at "[m]ore than 4,570 recipes from 93 cookbooks representing traditional, meat-based cuisines of 36 countries," as well as the antibacterial properties of the spices used. Their report found that where spoiled food is more of a concern, spices are more frequently used. The authors write:
Countries with hotter climates used spices more frequently than countries with cooler climates. Indeed, in hot countries nearly every meat-based recipe calls for at least one spice, and most include many spices, especially the potent spices, whereas in cooler countries substantial fractions of dishes are prepared without spices, or with just a few.
Beyond peppers, the research looked at less pungent preservatives. Garlic, onion, cumin, thyme and black pepper were all found to have antibacterial properties. Paul Sherman, an evolutionary biologist and one of the report's authors, noted that lab tests on 30 common spices have shown that "at least half of them kill or inhibit 75 [percent] of the bacteria they have been tested on."
Sherman also looked at vegetable recipes and found that spices are less common in them than meat dishes. This finding bolsters the theory. If spices were only about the taste, one would expect them to be found in equal proportions. It also deflates another theory that spices are preferred for their nutritional value, as vegetables are eaten in much greater quantities.
As Sherman puts it: "Everything we do with food — drying, cooking, smoking, salting, or adding spices — is an attempt to keep from being poisoned by our microscopic competitors. They're constantly mutating and evolving to stay ahead of us. One way we reduce food-borne illnesses is to add another spice to the recipe."
These two hypothesis may prove to line up with further research. It's possible our evolution led us to enjoy pungent food, while our natural thrill seeking behavior spurred us to cultivate peppers of unnatural heat.
Why we like what we like
A baby eats a bell pepper with his father. Preference for spicy foods, like all foods, is the result of a complex interplay of genes, culture, memory, and personality. (Photo: rabble / Flickr)
Of course, this article has ignored one crucial point: Not everybody likes the same level of heat and some people don't enjoy spicy foods at all. If people evolved a taste for spice, either for the thrill or its cleaning properties, why don't all people enjoy a nice chili eating contest?
As will surprise no one, the answer is that taste is complex. The number bumps of on your tongue, called papillae, can make you a "supertaster" or a "subtaster." Genes influence how your taste preceptors perceive flavors like bitterness. A bad childhood experience can turn you off to a food for life. And the interplay between culture and taste preference, as argued by John Hayes, is a chicken and egg problem.
"Is it that cultures use a ton of cilantro have a low proportion of people who find it soapy? Or, the other possibility is it just part of the cuisine so they just learn to deal with it," Hayes, associate professor of food science at Pennsylvania State University told U.S. News. "We don't know."
Hayes's research has even shown a link between taste and personality. In a 2013 survey, he found a positive correlation between sensation-seeking and reward-sensitive personality types and those who liked spicy foods. This supports Rozin, but the antibacterial hypothesis isn't out yet.
While not everybody likes spicy food, other popular flavors display bactericidal properties, too. Sherman's study showed that mint and sour foods, like lemons and limes, are also bacteria inhibitors.
And your brain may still register a food's clean burn, even if it isn't consciously palpable. When peppers were introduced to Europe, the Hungarians cultivated them into bell peppers. Sweeter and less pungent, the bell pepper nevertheless maintains antibacterial properties. And research out of the University of Southern California found that the carbon dioxide in fizzy drinks triggers a burning sensation in our pain sensors, the same response as horseradish albeit at a lower intensity. (Soda, it seems, hurts you in more ways than empty calories.)
Taken together, our understanding of taste would give any Martian anthropologist, and our human scientists, a lot to consider. Ultimately, how one species of primates came to mix pain, pleasure, and sustenance remains a tasty mystery.
Dominique Crenn, the only female chef in America with three Michelin stars, joins Big Think Live this Thursday at 1pm ET.
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Credit: Gunawan/Nature magazine
Students who think the world is just cheat less, but they need to experience justice to feel that way.
- Students in German and Turkish universities who believed the world is just cheated less than their pessimistic peers.
- The tendency to think the world is just is related to the occurence of experiences of justice.
- The findings may prove useful in helping students adjust to college life.
The world is just? That’s news to a lot of people.<p>The study is the most recent addition to a long line of work focusing on the belief in justice, our behavior, and our reactions to evidence that might suggest injustice occasionally occurs. This study focuses on a personal belief in a just world, (PBJW) rather than a general belief in a just world (GBJW). The difference between them must be highlighted.</p><p>GBJW is the stance that justice prevails all over the world and that people tend to get what they deserve. PBJW is more focused on the individual's social environment and their belief that they tend to be treated justly. While several studies show PBJW correlates with a higher sense of well-being and a variety of other positive effects, a high GBJW is associated with less life satisfaction, negative behavior, and callousness towards the suffering of <a href="https://link.springer.com/book/10.1007%2F978-1-4939-3216-0" target="_blank">others</a>. This study controlled for GBJW, and focused on PBJW as much as possible. </p><p>To assure that culture was not a factor, the study included students at universities in both Germany and Turkey. </p><p>The researchers gave students at the four participating universities a series of questionnaires that asked if they ever cheated in class, if they perceived the world to be just, if they though that justice always prevailed everywhere, their tendencies towards socially appropriate behavior, their life satisfaction, and if they felt like they were treated justly by their teachers and fellow students. </p><p>The answers were statistically analyzed for relationships. While some of the connections seem trivially true, others were surprising. <strong></strong></p><p>PBJW turned out to only be an indirect predictor of if a student was likely to cheat. Both a belief in a just world and a lower likelihood of cheating were mediated by the justice experiences of the students, with more of these positive experiences lowering the rate of cheating and improving their belief in justice. This was also associated with higher levels of life satisfaction. </p><p>These effects existed across all demographics in both countries. </p>
What does this mean? Is a belief in justice a self-fulfilling prophecy?<iframe width="730" height="430" src="https://www.youtube.com/embed/6oMv-azHNCA" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p>In a way, it seems to be. People who have reason to think the world is just to them tend to interpret events in a way to sustain that belief and behave in a just manner. In a larger sense, the take away from this study is that experiences of justice, both from peers and instructors, is vital to student's wellbeing and understanding that the rules that exist about cheating are part of a larger, legitimate, system. </p><p>The researchers, citing previous studies on the perception of justice, note that "justice experiences (1) signal that university students are esteemed members of their social group, which in turn conveys feelings of belonging and social inclusion and (2) motivate them to accept and observe university rules and norms. These cognitive processes may thus strengthen their well-being and decrease the likelihood that they cheat."</p><p>The authors also suggest that if you want people (not only students) to act justly; consider treating them with "civility, respect, and dignity."</p><p>Sometimes, all it can take to help somebody act virtuously is to treat them well. Likewise, people treated harshly can rarely find reason to play by rules that don't protect them. The findings of this study will certainly add to the literature on how we perceive justice in the world around us, but might also help us remember that there are real consequences to our actions which can be much larger than we imagine. <strong></strong></p>
This could change how researchers approach vaccine development.
- The reason children suffer less from the novel coronavirus has remained mysterious.
- Researchers identified a cytokine, IL-17A, which appears to protect children from the ravages of COVID-19.
- This cytokine response could change how researchers approach vaccine development.
A member of staff wearing personal protective equipment (PPE) takes a child's temperature at the Harris Academy's Shortland's school on June 04, 2020 in London, England.
Photo by Dan Kitwood/Getty Images<p>Experts don't want to place kids at the back of the line, regardless of how strong their immune systems appear. At least one company, Moderna, <a href="https://www.businessinsider.com/coronavirus-vaccine-for-kids-moderna-plans-pediatric-trial-2020-9" target="_blank">hopes to begin testing</a> vaccines in pediatric volunteers by year's end.</p><p>Innate immune response is especially high during childhood (compared to adaptive immunity). This makes evolutionary sense: nature wants an animal to survive until its ready to procreate. Turns out the children in the study possessed high levels of cytokines that boost their immune response. The biggest impact is made by IL-17A, which appears to protect the youngest cohort from the ravages of the coronavirus. </p><p>While both age groups produced antibodies to fight off the infamous spike protein, adults that produce neutralizing antibodies actually suffer a <em>worse</em> fate. Herold says this "over-vigorous adaptive immune response" might promote inflammation, triggering acute respiratory distress syndrome (ARDS). </p><p>This matters for vaccine development. As Herold says, </p><p style="margin-left: 20px;">"Our adult COVID-19 patients who fared poorly had high levels of neutralizing antibodies, suggesting that convalescent plasma—which is rich in neutralizing antibodies—may not help adults who have already developed signs of ARDS. By contrast, therapies that boost innate immune responses early in the course of the disease may be especially beneficial."</p><p>Herold says current vaccine trials are focused on boosting neutralizing-antibody levels. With this new information, researchers may want to work on vaccines that boost the innate immune response instead. </p><p>With <a href="https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html" target="_blank">at least 55 vaccine trials</a> underway, every piece of data matters. </p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank" rel="noopener noreferrer">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
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