Brain expansion: different theories about rapid expansion (Evolution)

by David Turell , Tuesday, September 08, 2020, 15:13 (1324 days ago) @ dhw

DAVID: In humans neurogenesis is mainly limited to small neuron additions to the hippocampus. Shrinkage in our brains is the result, primarily, of rearranging many of the extra neurons into effective circuits and discarding the unused. Of course the natural result is slight enlargement of some regions. Your theory is pure supposition in the face of these known facts.

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?

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.

DAVID: There is no way your 'intelligent cells' could understand how to prepare for the future.

dhw: I don’t know how often you want me to repeat that my ‘intelligent cells’ did not prepare for the future. I have bolded yesterday’s reply. Why do you persistently ignore your own description of how they work – by reaction, not by anticipation?

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" - a response which you have ignored above.

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.

DAVID: Our brain lay fallow from (current science) 315,000 years ago until about 50,000 years ago with better language. But it was ready for the new burst of activity due to advanced planning with the complexification mechanism ready to go.

dhw: Also dealt with over and over again. Yes, the complexification mechanism was ready to go. But the complexification mechanism only functions when there are new requirements to make it function. And so there was a period of stasis until new ideas resulted in new requirements. So what do you think was planned in advance?

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: So let’s forget about God’s anticipation of the many uses to which we would put our brain, and the prophecy that we would dominate the world, and what we are left with is that approx. 315,000 years ago our brain expanded to its present size. It was ready to react to new requirements whenever we came up with them.

Answered above. Stasis unexplained if enlargement is driven as you describe.

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.

Thank you, but I think God keeps hands on.