Brain expansion: different theories about rapid expansion (Evolution)

by David Turell @, Thursday, September 17, 2020, 18:30 (38 days ago) @ dhw

DAVID: And I answer stasis does not present new requirements as the Moroccans. New uses 35,000 years ago shrunk the brain! Your theory is inconsistent with fact.
And later:
Stasis in the Moroccans disproves your theory.

dhw: It does no such thing. Stasis relates to the period AFTER the expansion of the brain, when there were no new requirements. My theory concerns the CAUSE of the expansion. Nobody knows, but what we DO know is that the modern brain complexifies and in some areas expands bbin response to new requirementsbb. This process, as you have agreed, takes place without any intervention from your God. And so I keep asking you why it is not feasible that the same process would have taken place in the past, with the brain producing more cells, as these were then required, though we do not know specifically what these requirements were. The shrinkage in the modern brain, as we have agreed, was due to the enhanced efficiency of complexification, which made some cells redundant. You have agreed to every single one of the above points.Now please answer my repeated and bolded question.

DAVID: You are making a mountain out of a molehill looking at the slight enlargements from complexification. Using what we know (not theory) the only new neurons in adults are in the hippocampus from added memories. Using the rule, we agree to, that previous brains followed the same patterns of development, where did the huge additions of neurons (200 cc volume) come from? Your theory is apples to oranges of extrapolation.

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?

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.


DAVID: Your narrow view keeps ignoring the hippocampus, a center for memory which does add neurons to a small degree as we age and add memories. For you that means an entire brain can make 200 cc enlargements in evolution.

dhw: The hippocampus is integral to my theory! If the modern brain can add neurons, no matter how few, how does that demonstrate that earlier brains could not have added neurons?????

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.

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


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