posted on Jun, 20 2012 @ 08:16 AM
Originally posted by Barcs
Originally posted by swan001
reply to post by Barcs
A pressure does trigger evolution.
This pressure came from the Ice Ages. If I remember correctly, the last one was in -100 000. We started to cloth, hunt, stay warm (and that meant we
had to build tools).
But why only "we"? Why this pressure didn't trigger that same evolution unto other human-like mammals?
Why were evidences found that our ancestor's brains literally outgrew its skull capacity?
I'm not trying to be a smart alec, but a brain can never outgrow its skull capacity. The skull can change, and the brain size is directly
proportionate to cranial capacity. Looking back at our ancestors, brain size shows slow change over time as well. Last "ice age" (glacial period)
was from around 10,000 BC to 110,000 BC give or take. That's about a hundred thousand years. Humans aren't the only ones. We once shared the
earth with several hominid species with similar intellect as us. We survived while they did not.
For reasons unknown, too. I personally don't buy the "we forced them out", "we invaded them", "we killed them off" or whatever. Those other
hominids were here long before we got here and had survived several ice ages/interglacials/interstadials so they were clearly adapted to the
Toba, around 74,000 years ago, pushed all hominid species to the brink. That's what created the genetic bottleneck. The world was already heading
into the most recent ice age (cold period) and Toba pushed the global temps into the freezer. By some estimates it took the populations 20,000 years
to recover. We were that close to checking out for good.
My guess is that we simply outbred them. All you'd need is just a slight drop in the birth rate in the other hominids, combined with a slight rise in
the Cro Magnon birth rate, and in pretty short order you could replace an entire population by default. No violence needed.
And let's not forget H. floresiensis, which was totally unknown till just a few years ago. They survived right down to about 12,000 years ago.
We are the only animal who achieved high technology... just because of an Ice Age?
Certainly not JUST because of an ice age. For the past 2.5 million years we have been in an ice age that has bounced back and forth between warm and
cold. We are in a warm interglacial period right now. Humans are the sole survivor out of all the hominids, probably because of our
Well, I don't know about that. Neanderthals had a larger brain volume than Cro Magnon, and both of them had larger brain volumes than we do now.
You don't evolve a big brain unless you're going to use it. Big brains require lots of energy--half of the calories you take in every day go to feed
it. Your body will shortchange every other organ just to keep it running. Those energy requirements mean lots of food and calories (meat in
particular), which means a big expenditure of energy to get it.