Brain expansion (Evolution)

by dhw, Wednesday, July 29, 2020, 10:30 (1368 days ago) @ David Turell

DAVID: What happened to 'forced by a new idea'.

dhw: “Forced” is your word, not mine, but in any case my comment above is a response to your claim that my theory is inconsistent with sapiens history. I have shown you that it is not.

DAVID: Your changed theory is consistent, but previously you said an earlier-brained homo had an idea, which idea in order to be implemented had to demand an enlarged brain that naturally appeared:
"Yes, the larger brain would have required more feeding. Yes, once the brain had expanded, it would have been able to design and develop more intelligent and efficient tools. How does this invalidate the proposal that each expansion was triggered by a new concept from the smaller brain? How does it prove that developing and making the FIRST artefacts could not have been the cause of the expansion?" From April (2020-04-04, 14:06)

DAVID: Quite clear to me and the long stasis in sapiens does not support it
And later:
DAVID: You have never explained the idea that if a new idea drove brain expansion why the long stasis before implementation in the new brain. I view the drive of a new idea should have continues into an immediate action by the new-sized brain. But it doesn't.

You keep quoting me and then disregarding the quotes! Implementation of the new idea CAUSED the expansion! (But nobody knows what new requirements caused any of the expansions. We simply took the spear as a concrete illustration of the process.) AFTER the new-sized brain had come into existence through the implementation of the new “big” concept, for thousands of years there were no new “big” concepts that would have demanded any further changes to the now bigger brain. Hence stasis. That applies to all the expansions. But when sapiens’ new ideas did come along, they were implemented through complexification (and only minor expansions). The theory is supported by the known fact that the modern brain changes (complexifies and expands on a minor scale) IN RESPONSE to new requirements. It does not complexify or expand in anticipation of new requirements. Now please tell me what has changed in my theory.

DAVID (re shrinkage): Your assumption that the extra neurons were never used, is not my theory. My point is that many of them were used in the plastic reorganization of our brain to fit our new uses and needs. I assume old and new neurons were discarded as unnecessary after the reorganization.

No, my assumption is that the extra neurons WERE used to implement whatever caused the initial expansion, but were not needed subsequently, when eventually complexification took over from expansion. I really don’t know why you think the whole brain had to be reorganized. In what way? Do you think the cerebellum became the cerebrum, or what? I would assume that all the different areas remained the same, but some of them simply discarded cells that were no longer needed. Too simple for you?