Brain expansion: different theories about rapid expansion (Evolution)

by dhw, Wednesday, September 09, 2020, 07:00 (409 days ago) @ David Turell

dhw: Yes, we know that modern expansions are small, and shrinkage is due to the efficiency or effectiveness of complexification. How does this exclude the possibility that in former times, when there were far fewer neurons, the circuits were not effective enough to meet new requirements, and therefore the SAME autonomous mechanism which adds a few cells today added lots more cells then?

DAVID: Well we know lots more cells were added all at once over several steps. I do not accept a natural cause because of all the anatomical impediments I've listed that required coordinated design. Your supposition is a straight line extrapolation based upon one small aspect of facts we have to observe.

I don’t know why you persist in using the word “natural”, as if somehow it excluded your God as designer. If he designed a mechanism which led to AUTONOMOUS complexification and small-scale addition of cells in the modern brain, as you yourself believe, firstly this is hardly “one small aspect”, and secondly the SAME mechanism might well have led to AUTONOMOUS complexification and large-scale addition of cells in earlier brains. But yes, it is a straight line extrapolation from the only facts we have.

DAVID: In our brain extra cells are already present to reorganize. Where did all the extra cells come from in past 200 cc enlargements? There had to be novel neurogenesis driven by what force? I'm with God.

dhw: The “novel neurogenesis” in past enlargements would have come from the same force as the “novel neurogenesis” today: namely, as you so rightly say, the AUTONOMOUS “adaptability to react to any and all physical and mental and emotional demands we place on it” – a mechanism for complexification and expansion (= addition of cells, whether few or many) which could have been invented by your God. NB REACT TO, and not "prepare for the future"….

DAVID: My view is a holistic approach taken from all the broad range of facts we have. Your proposal of response to demands, as above, implies to me the driving force should result in immediate production by an advanced brain, but we both agree there are thousands of years of stasis. If the needs are so strong there is massive enlargement, why are there no new results? Your theory has no logic.

The quote concerning response to demands is from you, describing how the brain works.
I don’t know how often you want me to repeat my proposal regarding stasis, but here we
go again: the brain expanded when unknown new requirements could not
be met by the existing smaller brain. Once those requirements were fulfilled, the new
sized brain did not need to change until it had to meet the next new requirements
(e.g. new ideas, ways of life, changes of environment), and we see periods of
stasis following every expansion including ours. The brain changes as required. It does
not change in anticipation of new requirements. Our own brain apparently underwent
changes after a stasis of some 280,000 years, when there was a sudden burst of new
From this repetition, we moved onto your notions of God’s advance planning and "anticipation", which had shifted from emphatically none of our inventions to maybe some of our inventions to a prophecy that we would dominate the world, and then to the following:

DAVID: What was planned in advance was our large human brain ready to go when we learned how to use it. Our God-given brain.

dhw: And that is all that your God had planned, and pre-sapiens brains would also have been ready to react to new requirements until they needed greater cell capacity (like the hippocampus today). You say he dabbled expansion 315,000 years ago. I propose that he didn’t need to dabble, because (theistic version), he had already set up the mechanism which would do the expanding, as all stages of brain expansion used the same autonomous adaptability to REACT to all demands placed on the brain. I’m happy to leave it at that.

DAVID: Thank you, but I think God keeps hands on.

Yes, I know you think your God performed a brain/skull/pelvis operation on a bunch of sleeping Moroccans, but now his great plan was simply to make their brains do what every preceding brain had always done: to adapt in reaction to new requirements, as you have said yourself. And you still haven’t found one good reason to reject the possibility that the autonomous mechanism (perhaps designed by your God) which gave Moroccans this ability, leading to complexification and the addition of a few cells, might also have enabled past brains to complexify and add a lot more cells, as required at that particular time.

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