In a lineup of primates, humans are easy to spot. We’re the naked ones.
While all our living evolutionary cousins sport fur coats, Homo sapiens alone are naturally nude, aside from diminutive body hairs and dense tufts over our heads, underarms and genitals.
This has vexed scientists since Charles Darwin. In his 1871 The Descent of Man, Darwin asserted that fur loss is “an inconvenience and probably an injury to man.” Dismissing the possibility that nakedness evolved via natural selection — as a trait that improved survival — he attributed it to sexual selection — a trait fancied by mates. By this view, ancestors with less body hair were more attractive and reproductively fruitful.
Today most scholars lean the other way. They contend fur loss was not for sex, but survival — specifically, survival of the sweatiest. Reduced body hair enhanced the cooling capacity of sweat, a crucial adaptation in our ancestors’ hot, savanna-like environments.
“Humans can dump heat … whereas other mammals, when you chase them, overheat,” says Harvard University evolutionary biologist Daniel Lieberman.
