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

by dhw, Thursday, July 25, 2024, 07:22 (119 days ago) @ David Turell

DAVID: No one assumed the extra neurons were totally inert!!!

dhw: This is the problem when one is dealing with a schizophrenic. You agreed with me when I wrote that the early cells were able to meet all new demands: […]

Thank you. That does not mean they were superfluous for 290,000 years!

DAVID: Of course they were.

dhw: If they were superfluous, they were “inert”. But then you went on to agree that they WERE used - “in a minor way”. Another of your self-contradictions which for some reason you think make sense because you are schizophrenic.

DAVID: Not inert, slightly used, available for major complexification later on! You can't have complexification without cells available!

Of course you can’t. But if you say the extra cells were superfluous, it means they were not needed. “Slightly used” tells us nothing. They were used, and it would be totally pointless for the brain to take on additional cells if they were not needed. This applies throughout the history of brain expansion. You agree that your God plays no role in complexification. So it is absurd to argue that your God plonked the new cells into the first sapiens brain in order to prepare them to write, build cities, invent motor cars, fly to the moon, question his existence etc. He would simply have given them the ABILITY to do all these things. And the same principle could apply to the whole of evolution: speciation, lifestyles,strategies, natural wonders etc.

DAVID: Brain cells are very especially different types of cells. God designed evolution by Himself, not your weird secondhand design theory.

dhw: So your all-powerful God provided brain cells with the autonomous ABILITY to respond to future requirements, but he could not have done the same for other types of cell. Why not?

DAVID: Neurons are very specialized cells, not equivalent to other cells.

dhw: How does that come to mean that other cells which perform different functions cannot have been given the same autonomous ability to complexify and to process and respond to new information. The brain could hardly perform all its functions if it did not cooperate with other cell communities.

DAVID: The brain is the only organ which can complexify. Everything else is stable.

So how come that legs can turn into flippers or light-sensitive cells into eyes or gills into ears?

“De novo”

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.

dhw: First of all, “de novo” creation in the Cambrian remains a theory.

DAVID: What theory? Isn't the gap real?

dhw: Yes, but the proposal that an unknown, eternal, sourceless mind created species “de novo” is just as theoretical as the proposals that the fossil record is incomplete, or that intelligent cells are capable of major jumps if new conditions require or allow them.

DAVID: All theories are theories, never fact.

dhw: Correct. So “de novo” creation remains a theory, although the gap is real.

DAVID: A 'real' Cambrian gap makes the animals de novo no matter the cause.

The gap is real because we cannot fill it. It may remain real if there are no fossils, or if it can be proved that intelligent cells are capable of innovative jumps, or if it can be proved that there is a God who created species de novo. Otherwise, it simply remains an unsolved mystery.

dhw: 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?

DAVID: Sure, we evolved from earlier forms, which did not have five layers of pyramidal cells, a giant new phenotypical change.

dhw: Thank you. “De novo” means starting afresh from the beginning. But every expansion of our ancestral brains entailed the addition of cells that were not there before, and every evolutionary innovation (= something new) required changes to existing structures.

DAVID: True.

dhw: Thank you. We now agree that sapiens brains evolved from earlier brains, as opposed to their having been designed “de novo”.

DAVID: And accept our frontal lobes are a gigantic jump in form.

Yes. I only objected to the claim that sapiens brain had been designed “de novo”.