These examples suggest a twist on “You are what you eat.” More accurately, you are what your ancestors ate. There is tremendous variation in what foods humans can thrive on, depending on genetic inheritance. Traditional diets today include the vegetarian regimen of India’s Jains, the meat-intensive fare of Inuit, and the fish-heavy diet of Malaysia’s Bajau people. The Nochmani of the Nicobar Islands off the coast of India get by on protein from insects. “What makes us human is our ability to find a meal in virtually any environment,” says the Tsimane study co-leader Leonard.

Studies suggest that indigenous groups get into trouble when they abandon their traditional diets and active lifestyles for Western living. Diabetes was virtually unknown, for instance, among the Maya of Central America until the 1950s. As they’ve switched to a Western diet high in sugars, the rate of diabetes has skyrocketed. Siberian nomads such as the Evenk reindeer herders and the Yakut ate diets heavy in meat, yet they had almost no heart disease until after the fall of the Soviet Union, when many settled in towns and began eating market foods. Today about half the Yakut living in villages are overweight, and almost a third have hypertension, says Leonard. And Tsimane people who eat market foods are more prone to diabetes than those who still rely on hunting and gathering.

Manoel Davi Carneiro