Homo sapiens has no shortage of distinguishing features: We alone among primates are furless (that most mammalian of characteristics); we are the only species clever enough to ponder why that might be; and we can ponder such matters while pacing back and forth on two legs. Our cleverness, however, hasn't helped us determine why we have these qualities, but as recent developments in the hirsute-less debate reveal, they make for interesting pondering.
A mammal needs a good reason to discard its woolly coat. Fur shields the sun, barricades the cold, and protects the skin from abrasion. Of the few mammals that have dispensed with it--whale, elephant, walrus, pig, dugong, manatee, rhinoceros, hippopotamus, naked mole rat, and humans--most live in water, where fur is useless.
Unable to see a furless survival advantage for terrestrial humankind, Darwin ascribed it rather vaguely to sexual selection, whereby competition for mates drives the evolution of ...
