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To: metmom
Not to mention our tremendous brain had to evolve long before it gave us any advantage. To support it, babies have zero defenses for the first couple of years of life and have no chance at all against most predators for many more years after that.

And that brain doesn't actually peak until your fifties -- long after average live expectancy at all times except that latter half of the last century.

Its survival advantage is largely found in our organization, specialization and very advanced tool making none of which were possible when the brain would have evolved. In evolutionary terms, it would have been a huge cost with no apparent advantage until it has been around a while and had time to solve problems. Gradual improvements only make the problem worse -- a person with an IQ of 50 still has a brain that is large and very expensive for the organism.

So you are left with a random baby born that is more helpless for longer and looks odd, but won't see any real advantage for at least 20 years, if it lives that long.

65 posted on 12/30/2011 7:11:40 AM PST by hopespringseternal
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To: hopespringseternal

Actually, you’re close but not quite there; the idea of gradual change is more accurate.

You see, in our present form - as I believe you noted - humans are born early compared to many other mammals. While a calf or a kitten is on their feet moments after they are born, humans take quite a bit more time. However, do note that cows and cats have decidedly sophisticated brains already.

On the far opposite end of the spectrum, you can examine insect brains to look at an amazingly functional yet extraordinary simple (compared to humans) structure.

The important thing is this: moving back quite a long time, the ancestor of humans would have been much less intelligent as we measure it and much quicker of gestation; the same changes that allowed for the survivability of the great apes set the stage, if you will, for the changes that provided for increased cranial space, accompanied by increased time spend in infancy (to allow for the head/pelvis difficulty); we arrived at tool use as a major survival trait at a point when we already were surviving via other traits too.

By way of example, did you know that humans are quite impressive distance runners? It’s a consideration that when humans began to hunt large prey, they could afford to run them down and wait for them to overheat.

You pose a good question, but one that has been answered for quite some time by our understanding of human evolution.


124 posted on 12/30/2011 12:16:33 PM PST by Muridae
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