Brain expansion: different theories about rapid expansion (Evolution)

by David Turell @, Wednesday, September 23, 2020, 20:17 (395 days ago) @ dhw

DAVID: Feasibility simply means possible. But we can't accept anything is possible. Facts: London cabbies enlarged the hippocampus. Illiterate Italian women rewired their brains and used deep structures, the thalamus and the brain stem rewiring to the cortex, not enlarging. The hippocampus is a highly conserved ancient part of the brain deep in the temporal cortex going back in evolution about 200 million years. It is specific to memory and emotional states. Our brain enlargement involved 200cc more of frontal and prefrontal cortex. I assume the previous brains set up the current usage, accepting common descent. For me using hippocampal enlargement to explain prefrontal cortex growth is a non-starter. You are explaining apples by using cranberries.

dhw: Thank you for all these disjointed fragments of information, but none of them explain why the theory is not feasible, and your conclusion entirely misses the point. 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.

Totally connected. 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.


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.

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

dhw: It is not clear that enlargement LED TO advances. The modern brain shows that it RESPONDS to new needs; it does not anticipate them.

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.

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

DAVID: You have forgotten the error discussion.

dhw: I wish I could.

DAVID: The problem for me is simple. Cells make molecular errors. Therefore God has to have hands-on control of each step in evolution.

dhw: Errors are mistakes, i.e. something goes wrong. This is self-evident when we talk about disease-causing errors. But if the behaviour of cells deviates from established behaviour in evolution, either the behaviour is an “error”, in which case goodbye to the organism, or it will produce something different and functional (hence speciation), in which case it is not an “error”... 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.

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

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