Some Like It Hot

Philosophers have often looked for the defining feature of humans — language, rationality, culture and so on. I’d stick with this: Man is the only animal that likes Tabasco sauce.

– Paul Bloom, Professor of Psychology, Yale University

I have often watched friends chomp down on chillies without any hesitation and wondered how and why I turned out so differently. When I try to do the same, I end up a teary, red-faced, steam-emanating-from-the-ears mess.

As a person whose spice tolerance peaks at about three tiny green chillies, I am in awe of the high thresholds of the people who seek out the spiciest chilli peppers for their sauces, as well as curious as to what made their taste buds so different.

The limited edition Tabasco Scorpion Sauce (Source: Tabasco)

The Louisiana-based McIlhenny Company, manufacturers of the iconic Tabasco Sauce that adorns many a dining table all around the world, announced a limited edition Scorpion Sauce a while ago, which is the hottest the company has to offer at present. The Scorpion Sauce is reportedly twenty times hotter than the usual Tabasco sauce. Its main ingredient is the eerily titled Moruga Scorpion Pepper, which currently holds the title of the second hottest chilli in the world.

Despite the hefty two-million-Scoville-unit tag the chilli pepper carries and the company’s warnings that it was not meant “for the wary”, the Scorpion Sauce was sold out on the website within minutes of it going up for sale.

You may want to ask why anyone would willingly seek out such an intensely painful experience. How do we explain the appeal of a food that so many people consider painful?

Sugar, Spice and Everything Nice

The perception of taste physiologically refers to five basic qualities: Sweet, salty, sour, bitter and umami. The receptors for these tastes are located on the taste buds, which are large clusters of nerve endings on the surface of the tongue. For example, if you bite into a piece of cake, the different ingredients cause some receptors on your taste buds to activate and – along with cues provided by sight and smell – tell your brain that what you’re eating is in fact cake.

Pungency, however, isn’t normally classified as a taste. When someone describes the taste of a particular food as “hot” or “spicy”, they are actually describing a sensation called Chemesthesis.

A chemesthetic sensation is one where a chemical incites a response from the nervous system that you would normally associate with pain, touch and thermal perception, and these do not fit into the traditional categories of taste and smell.

Common examples of these include the tingly feeling you get in the nose and mouth from drinking soda, the tears induced by cutting onions, the cooling sensation of menthol in breath mints and mouthwashes and the burning irritation of chillies.

Spiciness is not even detected in the same manner as the basic tastes are. The compound in chilli peppers that causes them to be spicy is called capsaicin, and there are no specific taste receptors that detect it. Capsaicin normally activates the trigeminal nerve via receptors on the tongue that respond to pain and heat, called polymodal nociceptors.

So when you chomp down on a particularly piquant pepper, a specific type of nociceptor that detects changes in temperature gets activated, which tricks your tongue into believing that it is on fire, and your body reacts to the burning sensation as you would normally react to an increase in temperature: By your skin getting flushed or by sweating and panting in order to cool off.

The nociceptors aren’t restricted solely to the tongue. They can be found all over the skin and in the throat, among other regions. This is the reason why you can feel the coolness of menthol on your skin from various pain ointments, and also why it is a thoroughly well-documented fact that a really spicy curry will “burn on the way in as well as on the way out.

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Feeling The Heat

Despite their seemingly harmless appearance, most plants have developed ingenious defences against attack and being devoured by various insects and animals. Some of these range from growing in hard-to-reach areas and producing substances that are toxic to the attackers, to coating their fruit in thorns, wax or multiple layers of armour.

Another trick up the sleeves of chilli plants in particular is the production of capsaicin in its fruit – the chilli pepper – that makes it unpalatable to fungi, insects and most mammals. The very same chilli peppers, whose pungency drives away most herbivores looking for a meal, paradoxically advertise themselves with flashy colours and sweet smells to a particular group of animals: Birds.

While mammals have receptors on their taste buds that can pick up the presence of capsaicin, the same receptors in birds are insensitive to it, and therefore birds can gobble up chilli peppers like candy, without feeling any of the heat associated with them. But why do chilli plants allow birds this liberty? What do they stand to gain from it?

Their survival, for starters. Unlike mammals, when birds eat chilli peppers, they swallow the seeds intact. This allows them to eventually disperse the seeds via their faeces, and new chilli plants spring forth where the guano graces the ground. This veritable circle of life ensures the propagation and survival of the chilli plant species.

A Sayaca Tanager is seen eating malagueta peppers, which can be 40 times as hot as jalapeños. (Source: Alex Popovkin, Bahia, Brazil/Flickr)

The chilli plant’s seemingly foolproof defence strategy has proved counterintuitive against human beings, however. Humans have been cultivating chilli peppers for consumption since 7000 BC, and show no signs of slowing down today.

Scientists are baffled as to why we have taken such a liking to a chemical that produces the same effects in our bodies as tarantula venom, but Dr. Paul Rozin, psychologist at the University of Pennsylvania, has an explanation for this behaviour. In his paper titled “The Nature and Acquisition of a Preference for Chili Pepper by Humans”, Rozin suggests that when we slather our food in, say, Scorpion Sauce, we are indulging in what he terms as “benign masochism”.

Human beings actively seek out experiences that seem unpleasant or frightening but are otherwise completely safe, solely for the thrill. Activities like rollercoaster rides and eating the spiciest chilli peppers fall in this category, where the experience itself is scary or painful, but the experiencer is constantly aware that there is no threat to his life from the activity.

Rozin explains thus:

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… Mind over body. My body thinks I’m in trouble, but I know I’m not.

This kind of behaviour is uniquely human. Other mammals avoid chilli peppers altogether, whereas humans have taken something that was so obviously meant to be painful to us and turned it into something pleasurable, wholly by accident. There is no profound evolutionary significance as to why we developed a taste for spicy food. The consumption of chilli peppers come with a long list of health benefits, and historically the addition of chilli peppers to food has been known to have antimicrobial effects, but that still says very little about why we would happily look forward to the sweat, sting and tears from eating spicy food, or why certain chilli pepper aficionados are constantly on the lookout for a taste of the hottest pepper in the world.

The exact reasons still remain elusive; however, for the time being we can take perverse pride in the fact that humans remain the only mammals that have turned a response that normally signals danger into something so enjoyable.

Mollika Maiti is an author and scientist from Bangalore. She specialises in microbiology and is an avid quizzer.

This article first appeared on her personal site.

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