Evolution and humans: recent cave studies (Evolution)

by David Turell @, Saturday, June 17, 2017, 19:07 (177 days ago) @ dhw

dhw:It is not a matter of heavy use versus light use. The brain grew because there was room for it to grow without making the head too big for the body. Only when further expansion would have proved damaging to that balance did densifying replace growth. (I suggest that shrinkage is just a minor side effect of densification, which has become increasingly efficient.) The first manufacture of weapons would have demanded a veritable explosion of abilities: the concept of sharpening stone and attaching it to a shaft required finding the means of sharpening the stone and of making the attachment, experimenting to find the correct balance between shaft and tip, muscle coordination for the very act of throwing the spear. Of course it all seems very minor now, but we take for granted every new step taken by our ancestors. Concept first, brain "adjustment" (= expansion) second, realization of concept third.

What do the paleontologists find in their studies? They look at the produced artifacts by each hominin at a new brain size. Lucy had none we3 now of, but she still climbed trees based on anatomy and her brain size was chimp size. She was bipedal. At each of the next 200cc (average) increase the artifacts improve until we reach H. sapiens with a giant frontal lobe still in the stone age until 10,000 years ago and Native Americans in it until 500 years ago, and some remote tribes basically still there. Simple logic tells us as they received larger brains, they learned to produce more, and when the brain is intensively used it shrinks which is a small adjustment. There is no evidence to the opposite that beginning to use it enlarges it by 200cc, which based on the shrinkage size should have occurred in smaller steps, which are non-existent. Obviously, size first use second.

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