Two of the longstanding questions of human evolution are: Exactly when did our body hair become so fine as to render us practically bare-skinned compared to the other great apes? And why did we shift to walking truly upright rather than stay with the quite practical means of locomotion still used by chimps and gorillas? There's a tendency to think that posture preceded the hair thing, but it has occurred to me that if it were the other way 'round, one could very well be a contributing cause to the other. I'm aware of Hardy's aquatic ape theory ... it's unfortunate that the man undermined his credibility by taking it to silly extremes trying to make it account for EVERY feature of human physiology, and psychology as well, because there are certain things about it that make sense. We're the only great apes with webbing between our fingers, with a significant amount of subcutaneous fat, with relatively "hairless" skin ... all traits associated with decent-sized critters hanging about in wet spots in a warm climate. And there were significant amounts of wetlands and marshes in Africa way back when, in places that are savannahs today. So if a primate were having to face existence in a somewhat damp and squishy, not-to-many-trees-around environment, those with a tendency to insulate under the skin instead of on top of it and a slightly improved ability to maneuver in the deeper spots would, in the fine tradition of natural selection, last a little longer and so would their offspring who inherited those traits, increasing their percentage of the population bit by bit. A little more length in the hind legs would also be useful as well ... even if you're still doing the chimp-like version of upright, longer legs make wading easier.
The downside of this adaptation, of course, is that ape infants hang on by clinging to momma's body hair, leaving all her limbs free for maneuvering. So here's the actual ponder of the thing ... did that shift to modern posture eventually come about because the survival edge was just a little better for balding swampdwellers who were good at using their upper limbs to hang onto their kids instead of for locomotion?
Disclaimer: The writer of this post is fully aware that she hasn't laid eyes on a decent palaeo-journal in ages and is woefully behind on a ton of current knowledge. But what better way to fill the gaps than to throw this thing out to my multi-knowledgeable buddies so that they can let me know where my gaps, in logic or in knowledge, are? :-)
And yeah, re the userpic ... this is nothing to do with censorship (not where I live, anyway) but much to do with chimplike entities trying stuff out. ;p