Human evolution; savannah theory fading (Introduction)

by dhw, Tuesday, August 16, 2022, 09:05 (828 days ago) @ David Turell

Brain expansion

dhw: […] we don’t know why the human brain stopped expanding. You reject the idea that it might have caused anatomical problems, but you have not provided any other explanation.

DAVID: I have explained it!!! It is complex enough to handle all our needs into the future.

dhw: Thank you. I had forgotten. But I wonder why the ability to complexify was suddenly enhanced to the degree that expansion was no longer necessary. Did your God decide he’d had enough of performing all these operations on sleeping hominins and homos, and he’d leave all future “operations” to the cells themselves – apart perhaps from one final fling with the hippocampus?

DAVID: A designer knows when His design is complete.

Which brings us back to the question why your all-powerful God designed umpteen varieties of hominins, homos and brains before finally producing the only one he actually wanted to design. But of course, only God knows why, and he couldn’t possibly have been experimenting, or getting new ideas as he went along, because such a theory entails human thought patterns, and he only has those human thought patterns of which you approve.

dhw: Once more: if you believe your God gave past and present cells the autonomous ability to complexify, why do you regard it as impossible for him to have given all of them the autonomous ability to add to their number (as shown by the modern hippocampus)?

DAVID: With God in control, He did all He wished. What we see is obviously reflecting His exact wishes.

dhw: And how do you know his exact wishes, and how does this prove that he did NOT give cells the ability to multiplY?

DAVID: Cells do multiply. Why did you ask? And I have said we cannot know God's personal reasons.

You keep telling us that early brain cells could not have added to their number, and so God had to engineer their expansion (multiplication). Do you now accept that early brains might have had an autonomous mechanism for expansion as well as for complexification?

DAVID: And you have offered no answer for the pelvic problem as before.

dhw: I have given you the same answer I gave you before, but if you prefer your own theory that your God preprogrammed bigger heads and pelvises 3.8 billion years ago, or performed operations on all those women’s pelvises, that’s fine. Death in childbirth wasn’t all that uncommon in historic times, so it’s perfectly conceivable that such a problem would have caused more deaths in pre-historic times.

DAVID: You are very uncaring for our ancestors.

dhw: This has nothing to do with me “caring”! With your doctor’s knowledge of all the problems relating to childbirth, why are you so certain that our ancestors had no problems and God “arranged it so new heads fit into new sized brains all at once”? Has he been so uncaring for all those sapiens mums who never made it?

DAVID: It turns out our birth canal is still tough to navigate.

dhw: Yes indeed, so why do you think our pre-historic ancestors had no trouble back in the days when baby skulls got bigger?

DAVID: I'm sure they faced the same obstetric problems we do.

Probably a darn sight worse. So what is all this about God arranging it “so new heads fit into new sized brains all at once”?

Hemispherectomy

QUOTES: "Adults who had one half of their brain removed in childhood to treat seizures can still recognise faces and words at a reasonably high level, suggesting that the organ can reorganise itself after major childhood surgery.”
“The fact that above-chance and broadly comparable performance for face and word recognition can be achieved following childhood hemispherectomy attests to the remarkable adaptability of the juvenile brain,” says David Wilkinson at the University of Kent in the UK."

DAVID: Makes the point!!!

It certainly does. You could hardly have a clearer illustration of the way brain cells autonomously change themselves in order to meet new requirements. Or do you think your God pops in to perform additional operations after the surgeons have done their job?