Most furry mammals pant to regulate their body temperature. Other animals, like ectotherms — lizards, amphibians, and insects — have other behaviors that help keep them cool. Humans, however, are in a category of our own.
We are the only mammal that relies on secreting water onto the surface of our skin to stay cool: We call it sweating. But how did we develop this ability? When did we ditch the fur of our primate ancestors in favor of sweaty skin?