Evolution and humans: recent cave studies (Evolution)

by dhw, Saturday, June 17, 2017, 12:24 (2714 days ago) @ David Turell

dhw: Of course they were hides. And they were acquired by hunting. A quick google suggests that the first spears may even go back as many as 500,000 years. Name me one other animal that invents and makes weapons. Later came the use of hides as protection against the climate. Name me one other animal that cuts off the skin of another to protect itself. New concepts are new concepts, no matter how primitive they may seem to you, and each one may demand specialized use of the brain. Reading was a new concept to the illiterate women, and their brains responded to the new need by rewiring themselves, and so just as muscles respond to exercise by expanding, the brain would have done the same until it could no longer expand. Then, when it needed new abilities 12,000 years ago, it densified instead of expanding. I'm only theorizing of course, but can you fault the logic?

DAVID: Somewhat logical. Of course we are not like any other animal. Just think about it. Heavy use results in shrinkage; light use results in 200cc jumps in size every 1.5 roughly million years. Size first use second. Reading is way more complex than chipping a flint point and attaching it to a stick to throw. Of course the brain adjusted to this, but it grew instead of shrinking.

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.