Brain expansion: different theories about rapid expansion (Evolution)

by dhw, Thursday, September 24, 2020, 11:14 (31 days ago) @ David Turell

dhw: If we know for a fact that one section of the brain adds new cells when complexification cannot cope with new requirements, it is perfectly feasible that other sections of the brain could have done so in the past, when there were far fewer cells, which therefore had far less scope for complexification.

DAVID: We only know of the adult hippocampus in an existing form of the evolved brain, adding neurons for a specific purpose. The enlargement in humans was almost entirely in the frontal and prefrontal cortex, whose function is conceptualization and understanding the sensory inputs. I'm not discussing complexification with surplus neurons which can be added as needed to small areas. You are again hoping 'anything is possible' based on a distorted comparison.

There is no distortion. All compartments of the brain consist of cell communities with different (though often interconnected) functions. If one cell community can add neurons, so can they all. And they did! But according to you, it was your God who operated on the earlier brains and added the cells – but he didn’t have to operate on the modern hippocampus, whose cell community was able to do the addition all by itself. You simply refuse to acknowledge the possibility that the SAME mechanism which gives modern brain cells their autonomous ability to CHANGE in response to new requirements could have performed the same function in earlier brains, whether complexifying or expanding.

DAVID: The apes do/did just fine without this development, so why did it happen? My answer is God.

dhw: We can only speculate why ANY of evolution happened, because bacteria did and do just fine without it. But if you want a specific theory about humans diverging from apes, I would suggest that in some local area(s) our ancestors descended from the trees – maybe because of changing conditions – and their new way of life placed new demands on their brains, while other apes in other areas continued to live quite happily as they had always done. And I would suggest that this is the key to all evolution: that organisms (i.e. cell communities) responded in different ways to new requirements, just as the cell communities of the brain also responded and respond to new requirements.

DAVID: I know and reject your theory and stick with God, as that makes better sense to me.

You asked why the development happened, and I have offered you a theory. What does “I’ll stick with God” explain? The theistic version of my theory is that your God endowed all cell communities - including brains - with the ability to meet new requirements, and adapt to or exploit changing conditions. Your theory is that he either preprogrammed all the adaptations/exploitations (and the changing conditions?) 3.8 billion years ago, or he kept stepping in to perform operations on every organ (including brains) and organism he wanted to change – not to mention giving courses to every organism that produced a natural wonder.This is what you “stick” with.

DAVID: My view is that God provided the larger brain in anticipation of its future use.

dhw: I know that is your view. Please tell us of any proven instances in which the brain is known to have altered its structure in anticipation of new requirements.

DAVID: I think in every hominin enlargement when new artifacts are found, as before.

I asked you for proven instances, and all you can come up with is a repetition of your unproven theory that your God enlarged the brain in anticipation of the hominin producing new artefacts, whereas my theory is that the hominin’s brain expanded through the process of producing new artefacts! By contrast with your theory, I have the proven example of the modern brain, which changes IN RESPONSE to new requirements and not in anticipation of them.

dhw: In my theory, these changes are designed by an intelligence which your God may have designed at the beginning of the whole process. They are not "errors"!

DAVID: Again you want errors to run evolution. Why do the advances of evolution look so purposeful and designed? Your God gives up control, mine doesn't.

dhw: Read the bold! I have just stated explicitly that evolutionary changes are NOT “errors”. It was you at the beginning of the discussion on errors who told us (a) that God could not prevent them, and (b) that they changed the course of evolution! I have just said that in my theory evolutionary changes are DESIGNED (i.e. by intelligent cells), and elsewhere I have even specified the purpose: to improve chances of survival. But yes, my God does exactly what you have said he does in your muddled argument: namely, he gives cells the freedom to do their own thing instead of automatically following his instructions. See the other thread for further discussion.

DAVID: I don't accept your strange version of why errors occur. I have God in control.

Having told me I want errors to run evolution – the exact opposite of what I have said – you now refer to an explanation of why errors occur, whereas I keep repeating that in the context of evolution there are NO errors! You are the one who keeps harping on about evolutionary errors! In my theory, the changes are designed (by the cells). And how can your God be in control if he has given molecules the freedom not to follow his instructions? See the “errors” thread for further discussion.


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