A TV chef’s casual mention the other weekend got me thinking about why regions of the world with hotter climates have cuisines that feature spicy foods.

The two most commonly accepted reasons, as cited by the New York Times:

“If you are living in a hot climate, th e increase in body temperature [from eating spicy food] can make you feel cooler by diminishing the difference between you and the surrounding air and by inducing sweating, which cools the body when the perspiration evaporates.”

e increase in body temperature [from eating spicy food] can make you feel cooler by diminishing the difference between you and the surrounding air and by inducing sweating, which cools the body when the perspiration evaporates.” “Peppery foods are also believed to stimulate the appetite by setting off the flow of saliva and gastric juices, a nutritionally important effect for people in tropical areas where the oppressive heat acts as an appetite suppressant.”

However, Cornell University researchers believe those reasons are minor compared to this one: many spices have anti-microbial properties. In other words, herbs and spices, which have been proven to inhibit the growth of bacteria and other tiny nasties, are more widely used in hotter climates because the bugs grow faster there, especially on meat and other proteins.

The scientists even found an evolutionary advantage. Said one:

People who enjoyed food with antibacterial spices probably were healthier, especially in hot climates. They lived longer and left more offspring. And they taught their offspring and others: “This is how to cook a mastodon.” We believe the ultimate reason for using spices is to kill food-borne bacteria and fungi.

To conduct their research, the scientists looked at nearly 4,600 recipes from 93 cookbooks representing traditional, meat-based cuisines of 36 countries; the temperature and precipitation levels of each country; the horticultural ranges of 43 spice plants; and the antibacterial properties of each spice. According to the researchers:

Garlic, onion, allspice and oregano, for example, were found to be the best all-around bacteria killers (they kill everything), followed by thyme, cinnamon, tarragon and cumin (any of which kill up to 80 percent of bacteria). Capsicums, including chilies and other hot peppers, are in the middle of the antimicrobial pack (killing or inhibiting up to 75 percent of bacteria), while pepper of the white or black variety inhibits 25 percent of bacteria, as do ginger, anise seed, celery seed and the juices of lemons and limes.

Their objection to the eat-spicy-to-sweat hypothesis:

Not all spices make people sweat, and there are better ways to cool down — like moving into the shade.

The final conclusion: