Human evolution: savannah theory fading; big brain (Introduction)

by David Turell , Wednesday, March 19, 2025, 16:29 (14 days ago) @ dhw

The human brain

DAVID: God guided brain enlargement and complexity as needed by the new environmental changes. (dhw’s bold)

dhw: At least you now agree once more that complexity and enlargement occur IN RESPONSE to environmental changes, and not in anticipation. How does one “guide” enlargement and complexification? Did your God pop round to each pre-sapiens in the group with his X-Ray machine and scalpel, making sure the cells were arranging themselves in the right order?

As usual, you have ignored my question.

I have no idea how God enlarges brains or increases the complexity. But each increase provides for the present and future needs.

DAVID: Just because I didn't mention anticipation our 315,000 brain shows just that.

dhw: “As needed by the new changes” does not mean “as will be needed by changes that will not happen until two or three thousand years later”. […]. Once more: A response to new requirements does not entail anticipation.

DAVID: Our 315,000-year-old brain seems to handle all new requirements from its appearance when little was required of it. Of course that is anticipation.

dhw: What is anticipated? You have said that your God enlarged and complexified all stages of brain “as needed by new changes”, and that he does not intervene in complexification. So did he look into his crystal ball 315,000 years ago and decide he’d better give us a bigger brain so that we could invent writing, railways and rockets? I agree with you that each enlargement, including our own, arose out of need for a response to new conditions, and of course each enlargement would have led to future complexifications and future enlargements for the same reason. But in our case, further enlargement was replaced by an increased capacity for complexification. Your God may have designed the mechanism for complexification and enlargement, but it would hardly require divine “anticipation” to realize that each new brain would be used in the future!

The Erectus brain covered many complex problems, but could not handle today's requirements. Even though ours is 315,000 years old it works just fine. That is anticipation of needs.

The savannah theory

dhw: May I take it that you now agree that the savannah theory concerning the origin of sapiens is as logical as any other theory, including your own, in which your God operated on a group or groups of legs, pelvises and brains?

Yes the savannah theory is logical. But the real story is unknown.