Brain expansion (Evolution)

by dhw, Sunday, July 26, 2020, 11:17 (1579 days ago) @ David Turell

On the subject of expansion:

dhw: Do you or do you not agree that the modern brain complexifies when implementing new requirements? Our subject here is why the earlier brain expanded. The modern brain complexifies in response to requirements and even performs minor expansions. I argue that the same process may have been in action before sapiens, though in those times the brain needed greater capacity to cope with requirements, and so it was the mechanism for expansion that came into operation. You argue that the brain expanded BEFORE there were any new requirements.

dhw: As you have not commented on this, I will take it as read that you agree with my summary of our different approaches and have no issue with the logic of my own approach.

DAVID: I always have an issue with your theory if brain expansion. Fully explained many times.

Then please humour me. The modern brain implements thought by means of complexification and small-scale enlargement. Why is it illogical to propose that earlier brains also implemented thought by complexification, but when the brain did not have the capacity to implement thought by complexification, it added new cells, thereby leading to large-scale enlargement?

On the subject of shrinkage, and why David’s God would have given us 150 cc more than we needed.:

DAVID: We go 'round and 'round. I'll simply give you what is clear above: 'To allow us to use the brain as we wished so that the eventual brain would exactly fit our uses'.

dhw: “Clear”? It makes no sense! Why did he give us more brain than we needed for our uses? We didn’t need the extra brain for thoughts we didn’t have during the 270,000 years of stasis. And when we had our new thoughts, we still didn’t need the extra, so it disappeared. What wishes did the useless 150 cc fulfil?

DAVID: Please read carefully what I express, as it makes perfect sense to me. The larger brain allowed us through the mechanism of plasticity to tailor it for our exact future uses. And we did it.

That is the bit I do not understand. I’m sorry if you think I’m being obtuse. Please explain how the excess 150 cc, which stuck around for approx. 270,000 years not being used, “tailored” (whatever that means) our brain for the time when we would think our new thoughts which still wouldn’t use the 150 cc. Once again: If it was never used, why did your God put it there in the first place?

DAVID: London cabbies have thickened areas as a result of our God-given brain mechanisms. How do you explain the oversize?? You haven't ever tried!!! I do all the possible explanations and you never try any, only criticize. What is your thought about it?

It is not “oversize”! It is the size required and then reached for the implementation of ideas. ALL such changes are the result of the brain RESPONDING to new requirements! Cabbies need to memorize routes, and the effort to implement this requirement by doing the abnormal amount of memorizing has resulted in certain areas of the brain acquiring more cells (whereas most requirements are met by complexification). That is the whole principle on which my theory is based, and which I have summarized in the section you did not comment on. What I criticize is your belief that the early brain had to expand BEFORE there were any new requirements (which according to you ought to mean that the cabbies' brain areas thickened BEFORE they could memorize all the routes).

DAVID: The 150 cc disappeared into new networks of use by the plasticity mechanism and the system worked so well there were redundant areas that could be removed, and we ended up with a tailored brain that fit our needs exactly. Makes perfect sense.

dhw: Yes, it does. But it does not answer the question why your God inserted the redundant areas in the first place.'

DAVID: What is your explanation? It happened. Mine makes pefect sense to me.

I do not believe that your God inserted the excess in the first place, although he may have designed the autonomous mechanism that led to the excess. And your “explanation” makes no sense to me, as argued above. My explanation is that whatever caused the expansion to sapiens dimensions did require all the cells. It was only when expansion became impractical, and sapiens began to think his new thoughts, that complexification had to take over from large-scale expansion, and – as we have agreed over and over again – complexification proved so efficient that some of the previously necessary cells became redundant.