Narrator: This is Science Today. If you don't eat like your ancestors did, maybe you should. According to Douglas Wallace, a professor of Molecular Medicine at the University of California, Irvine, our metabolisms are optimized to our ancestral climates, suggesting that people from different climatic ancestries should eat different diets - regardless of where they live today.

Wallace: If an individual's lineage is adapted to a colder climate then a lot of the calories that they eat will go to be making heat. Since we need a constant amount of ATP to live, those people will need to eat more calories.

Narrator: But unlike our ancestors, today many of us change climates quickly, and adopt the local lifestyle - a practice that may increase our risk for developing obesity and diabetes.

Wallace: When people move from a tropical region, say in Africa, to a colder region like New York City and then adopt the lifestyle of the temperate people and start eating a higher fat diet, they are going to have an excess of calories.

Narrator: For Science Today, I'm Larissa Branin.