Frans Lanting Studio / Alamy
Mammals that hibernate for part of the year tend to have smaller brains than those that can feed all year round.
The finding may help explain why big-brained primates like us mostly evolved near the equator. It may be that our species arose in Africa, rather than neighbouring Europe, because Africa lies on the equator and much of it has only weak seasons.
Sandra Heldstab of the University of Zurich, Switzerland and her colleagues compiled data on 1104 mammalian species. They …