Brain expansion: different theories about rapid expansion (Evolution)

by David Turell , Friday, September 18, 2020, 23:14 (1525 days ago) @ dhw

dhw: The huge addition came from the same autonomous mechanism as the small addition. If the modern brain is capable of producing new neurons, then so was the ancient brain. The history of the brain is expansion after expansion, and we see a gradual increase in what we might call sophistication, coinciding with these expansions. We know from the modern brain (confirmed by you) that the brain changes IN RESPONSE to new requirements. Why should it have been different in former times?

DAVID: Same lame non-answer. We only know of new hippocampal neurons appearing. That should apply to ancient brains and nothing more. The response in our brain is the only fact we have on which to base theory.

dhw: And the response in our brain is always that it changes in order to meet new requirements. Sapiens brain stopped expanding. We don’t know why, though I have offered what I consider to be a feasible explanation (further expansion would have created major problems for the whole anatomy). Enhanced complexification REPLACED overall expansion, but we still have evidence that the brain is capable of adding new cells when necessary. And so…yet again…why is not feasible that the mechanism which now adds cells to the hippocampus when needed to meet new requirements, also added cells to other parts of the brain when overall expansion WAS possible and was needed to meet new requirements?

Our only proof of concept is what we know. You are supposing a mechanism that we do know naturally existed in the past based on the few enlargements in our current brain.

DAVID: Same stretch of enormous imagination.

dhw: I don’t find it any more “enormous” than the idea of your God stepping in time after time to perform operations on groups of hominins and homos to enlarge their brains, skulls and pelvises, although he knew all along that the only brain he actually wanted to design was that of H. sapiens.

DAVID: I'll stick with God while you search for a natural cause of brain enlargement.

dhw: My proposal does not exclude God. It simply takes his possible involvement back to designing the mechanism for what you call a “natural” enlargement, as opposed to having him conduct countless operations not just on hominid and homo brains, but also for every evolutionary innovation in life’s history, apart from those which he had preprogrammed 3.8 billion years ago.

We don't know if He pre-programmed or dabbled or both. The enlargements were not natural in my view.