Introducing the brain: why so big? Part two (Introduction)

by dhw, Sunday, July 21, 2024, 08:19 (49 days ago) @ David Turell

dhw: We are in complete agreement on the fact that the new cells which met the new demands 300,000 years ago have also been used to meet the new demands for the last 10,000 years. You have agreed that your God does not intervene in the process of complexification. And, wonder of wonders, here is your conclusion:

DAVID: God gave our brain the ability to complexify with the extra neurons only slightly used.

dhw: “Only slightly used” does not mean they were superfluous when – I suggest – they arrived in order to meet new requirements and succeeded in doing so. My theistic version of the brain’s evolution (as of evolution in general) is precisely what you have said: he would have given our brains (and cells in general) the ABILITY to make changes to themselves in response to new requirements. 300,000 years ago, he did not preprogramme the brain cells to read, write etc. Those were the complexifications resulting from the brain’s (perhaps God-given) ability to complexify. Agreement at last.

DAVID: We only agree upon how God handled it.

That is the whole point of the discussion. If he exists, he would have given our brains the ABILITY to change themselves in response to new requirements, as opposed to gazing into his crystal ball and preprogramming them 290,000 years in advance. Your agreement should also open the way to the possibility that the same applies to all of evolution: instead of a 3.8-billion-year-old book of instructions for every speciation, lifestyle, strategy and natural wonder, or countless ad hoc operations and courses on how to do this, that and the other, he might have given all cells the same autonomy as he gave our brain cells.

“De novo”

DAVID: You ignored the point: five layers of pyramidal neurons in our frontal lobes is entirely new. Our pyramidal neurons differ from mouse:
file:///C:/Users/pacemaker/Downloads/s41467-021-22741-9.pdf
Very complex article shows huge differences from mouse type.

dhw: All species have differences from other species! But all mammals have frontal lobes. The one fact that ours are different from theirs does not alter the other fact that there are multiple similarities between their brains and ours, and so our brains were not designed afresh from the beginning, as we inherited them from our mammal ancestors.

DAVID: This makes rubbish of the Cambrian Explosion gap being de novo. Those marvelous animals used DNA from former Ediacaran's genomes. Nothing is de novo by your tight definition of evolution.

First of all, “de novo” creation in the Cambrian remains a theory. Secondly, what are you claiming here? All DNA consists of biochemicals. You can use the same materials to create any number of new things from the beginning. The question is whether there is a direct line from species to species, or in this case, from brain to brain. From hominids to homos, there is a continuous expansion, through the addition of new cells. Do you or do you not believe that our brains, together with their additional "layers of neurons", evolved from earlier brains?