No more body hair
3.3 million years ago
Humans are the nearly-hairless apes. No one knows why, but it happened 3-4 million years ago. That’s when pubic lice evolved, which could only infest us once our other body hair was gone. Exposed to the Sun, our skin darkened. From then on all our ancestors were black, until some humans left the tropics.
See other: What Makes Humans Human?
Knowledge Guild 
I don’t recall if it was Robert Ardry (African Genesis) or Desmond Morris (The Naked Ape), who postulated a theory that during the time of near-extinction for our species, when roughly 2000 of us were divided between the Southern and Eastern Coasts of Africa, our ancestors spent sufficient time in the water, in search of food, that the water itself wore off our hair, except (generally) for that on our head.
Apropos of nothing (but then, this IS Knowledge Guild), in an interesting experiment, the video of which I’ve watched but haven’t the time to find, a mixed batch of head lice and pubic lice, were dumped onto the chest of a prone, nude man. They immediately separated, with the head lice heading (no pun intended) for the head, and their cousins for the pubic area.
“…our ancestors spent sufficient time in the water, in search of food, that the water itself wore off our hair, except (generally) for that on our heads.”
That this is possible, is evidenced by the evolution of dolphins from a dog-like land animal that found its food largely in the sea, to the smooth surface of the animals we know today.
Don’t mind the Americanism, but what’s up with the dolphin?
I was demonstrating the end product of a hairy animal evolving to a hairless one.
(Sorry it came out a little larger than I realized it would –)
What Americanism?
No problem :)
“What’s up with the…” ;)
Old joke:
Q: What do they call Chinese food in China?
A: Food
I didn’t recognize your phrase as an ‘Americanism’, as to me, it seemed a perfectly normal way of speaking. I’ve always wondered, as a native of Holland, how you seem so at ease with ‘Americanisms,’ your grasp of my language goes far beyond speaking and understanding it, you seem to grasp the idioms, as well as the American sense of humor (which, at times, can be quite bizarre!).
Surely you don’t think I’m actually writing this in Nebraska? ;)
No, but you once commented that something was ‘as big as Nebraska,’ and I found myself wondering how you knew how big Nebraska was. (BTW, it’s all corn – nothing to see there)
Speaking of corn, here’s a corny question I encountered on the interwebs recently “if you were a US State, which State would you be?”
Reminiscent of Barbara Walters’ famous, “If you were a tree, what kind of tree would you be?”
I’d be torn between California and Hawaii, with a leaning toward California, due to it’s great diversity of climate, terrain, and cultures.