Originally posted by TrueLies
monkey's are still monkey's if we all evolved from monkey's why aren't we seeing them even today trying to walk upright?
Why would a monkey try to walk upright?
if we did why can't they?
Think of it like this. You have a large population of chimp-like animals in east africa, over a wide geographic area. The environment is more or
less junglelike. Then the climate starts cooling (and we have evidence that it did), the jungle starts receeding, breaking up into smaller groups of
trees seperated by grasslands (and we have evidence that it did) and even the ground itself, due to plate tectonics, is rifting (and we have evidence
that it did). So the environment is slowly changing from jungle to grasslands. The environment is what supplies 'selective pressure'. The
'needs' to surivive in a jungle are different than in an open grasslands, so the pressure is different, so mutations and variations that are
favourable in that 'changing into grassland' environment are
beneficial. Whereas in a jungle they'd be
detrimental.
So what you end up with is something like east africa today, with a large grassy land in the east, then a huge rift, mountains, deep valleys, in the
middle, and then jungles again in the west. In the western jungles, the chimp-like ancestors ended up being under 'selective pressure' that favours
jungle-living adaptations, so that lineage didn't change much at all, since they were already adaptde to the jungle. But in the east, the
adapatations that were favoured were things like walking upright (instead of swinging arm by arm thru trees, because there weren't enough trees to
get around) which is a really efficient way of getting around on the ground,
and some added benefits. On the one hand, you'd have a higher
vantage point that a knuckle-walker, andon the other hand, you now have free hands, and then can carry stuff, and throw stuff, and hit rocks together
until they break in such a way that they have a sharp edge, and that edge can be used to scrape meat off a carcass quickly, and having lots of fatty
meat to eat means lots of calories and that means you can afford to 'waste'biological resources in order to support a big thinking brain.
So there's all these weird sort of unexpected things that can happen when the environment is changed and there are different selective pressures.
And teh selection pressure is why chimps still look like chimps, even tho a group of chimps, slowly, over generations, became like australpithecus,
and then homo habilus, and then erectus, and then cro magnon, and the like. Different pressures. There is no
benefit for a chimp that has
some weird mutation or just a natural variation in its bones that allows it to stand more upright for longer periods of time.
Another advantage of walking upright is the illusion of looking bigger than we are.
I hadn't even thought of that. That seems like another thing that could be beneficial, especially if you can't scamper off into the trees when
threatened.