"Antimicrobial Functions of Spices: Why Some Like It Hot" by Jennifer Billing and Paul W. Sherman, in The Quarterly Review of Biology (Mar. 1998), 110 Life Sciences Library, State Univ. of New York, Stony Brook, N.Y. 11794–5275.

Folk wisdom has it that people in hot climes favor "hot" food because pungent spices mask the taste of food that’s past its prime. In fact, the spices have a far more sophisticated function: killing or inhibiting bacteria and other microorganisms that can spoil food and threaten human health.

Billing and Sherman, a graduate student and a professor, respectively, in Cornell University’s Section of Neurobiology and Behavior, believe that the taste for spices is an evolutionary adaptation. They looked at how often 43 spices were used in the meatbased cuisines of 36 countries. Ninetythree percent of the more than 4,500 recipes they found called for at least one spice, and the average recipe called for about four. Onion (used in 65 percent of the recipes) and pepper (63 percent) were the most frequently used flavor enhancers, followed by garlic (only 35 percent), capsicums, lemon and lime juice, parsley, ginger, and bay leaf.

In 10 countries—Ethiopia, Kenya, Greece, India, Indonesia, Iran, Malaysia, Morocco, Nigeria, and Thailand—every meat-based recipe called for at least one spice. By contrast, in Finland and Norway, about one-third of the recipes called for no spices at all.

Not only did people living in hot climates, where the food is more likely to spoil, use many spices, and use them often, they also reached for the spices with the strongest antibacterial properties more frequently than people in cooler areas did. According to information gathered by Billing and Sherman, four spices—garlic, onion, allspice, and oregano—act against every bacterium on which they were tested.

Interestingly, lemon and lime juice and pepper, though among the most frequently used spices, are relatively ineffective against bacteria. Why are those spices used? Because they enhance the antibacterial effects of other spices, the researchers say.

The folk wisdom that spices are used to disguise the smell or taste of spoiled or contaminated foods is "seriously flawed," the authors maintain. Thousands of people are killed every year, and millions made ill, by ingesting foodborne bacteria. Even undernourished individuals would likely be better off passing up tainted meat. Using spices to disguise the danger would be evolutionary folly. Indeed, say Billing and Sherman, that may be precisely why humans are so sensitive to the smells and tastes of decaying food.