One gene, the leptin receptor, is increasingly common in areas with colder winters. Leptin is important to appetite and weight gain -- something people need no help with in modern times.
"We eat a lot more, we don't exercise nearly as much as our ancestors used to do, and these adaptations that made us cope well to a cold climate now make us prone to a number of metabolic disorders," Di Rienzo said.
She said the study sheds light on why some of these variants are more common in certain populations. "It helps explain the evolutionary origins of these diseases," she said.
