Chilli is spicy so that the chilli “pods” will not be eaten by mammals… and along comes the mammalHomo sapiens sapiens(i.e., we humans) and decides to enjoy the pain.

One has to wonder how this ever happened. Give a chilli to just about any mammal – dogs, cats, monkeys… all except for one species of tree shrew – and they will not eat it. Same with small children. But somehow, thousands of years ago in South and Central America, people started using chilli as a spice and then even began to grow it. Then, with and after Columbus, the chilli spread around the world and was welcomed in many places – and in recent decades, more and more people who had been holdouts on the chilli have also acquired a taste for it.

But why?

There are two better-established (and complementary) hypotheses about the popularity of the chilli, one psychological, one practical-evolutionary.
Sherman & Billing (1999) researched the use of spices, including chilli, in different kinds of recipes and in different climates. They found that hot spices used more in tropical and subtropical regions than in temperate ones.

This has been observed before, and people argued, for example, that the chilli perhaps promotes sweating, which helps to cool down. Sherman & Billing followed a different idea, though: They looked at the antimicrobial effect of the chilli, which may help keep people who eat more chilli safe from the pathogens (disease-causing organisms) that are common in meat, and especially problematic where temperatures are higher, so that meat spoils more quickly (i.e., in the tropics).

Fittingly, their study found that recipes with meat include considerably more spices than vegetable recipes. Thus, this may well be the underlying reason for the popularity of chilli in the world’s sub- and tropical regions: Those people who ate more chilli were healthier, and the practice spread like that.

Such an evolutionary effect works over generations and is quite possible, but it cannot fully explain what happened when Europeans and Americans, over a few years, started eating less ketchup than hot sauce.

Paul Rozin found two things in his research which help us understand more.

For one, he observed that children in places where lots of chilli is eaten are not born with a like for hot tastes, either. They react to hot chilli the same as all other mammals, and they are fed non-spicy foods. As they grow up, however, they will want and get more and more “adult food”, like children everywhere. Only that in such places, this means more and more spicy food.

With the regularity and normality of such spicy food, with the social pressure this means, it just becomes normal and okay to eat the usual spicy foods. (European children also learn to like smelly cheeses and other such delicacies which are not immediately appealing.)

The chilli has one more psychological ace up its… pod, however. Paul Rozin argued that eating spicy (and then spicier-again) foods also works as a form of “benign masochism.” That is, someone who eats chilli does something that is a bit painful, a bit uncomfortable, but still safe. And in this combination – which he compares to getting on a rollercoaster – it is a little thrill. One’s body releases dopamine and other hormones as it reacts to the “danger,” and those make one feel good.

So, think spicy, stay spicy – get happy! 

Paul W. Sherman and Jennifer Billing. Darwinian Gastronomy: Why We Use Spices: Spices taste good because they are good for us. BioScience 49(6): 453-463. 1999.

Paul Rozin and Deborah Schiller. The Nature and Acquisition of a Preference for Chili Pepper by Humans. Motivation and Emotion 4(7): 77-101. 1980