Mammals Evolve Faster in Hot Weather: Study

Evolution happens faster in warmer climates, a new study finds. Researchers found that DNA changes more frequently among mammals in the species-rich tropics than among comparable species elsewhere, the BBC reports. Scientists believe the germ cells that become sperm and eggs divide more often in hotter weather, perhaps because those mammals have greater metabolic activity.

Plant species and marine mammals also exhibit the same phenomenon. But because their body temperatures are regulated by the environment, scientists attributed the finding to changing metabolic rates. The weather doesn’t affect body temperature in mammals, but they do adjust their level of activity to the seasons. “In warmer climates annual metabolic activity is likely to be greater,” explains the study’s author. (More scientific study stories.)