Brain expansion (Evolution)

by dhw, Thursday, July 30, 2020, 11:51 (1338 days ago) @ David Turell

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.

dhw: 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.

DAVID: I object specifically to your bold. Sapiens in Morocco appeared 315,000 years ago with NO NEW changes in their lifestyle or artifacts. 50-70,000 years ago language started to appear. Caves were still used until much later. All stasis, no invention of the great idea you propose caused it!!! No evidence of anything new.

Whatever the “great idea” may have been, it would have PRECEDED the expansion, which was caused by IMPLEMENTATION. Stasis FOLLOWED the expansion until new ideas required changes to the brain, as below.
You keep talking as if the Moroccan sapiens meant an overnight change from pre-sapiens to sapiens. This has always seemed absurd to me. The whole human evolutionary process is shrouded in mystery, and the five Moroccans do not solve it, as this article shows:

World’s oldest Homo sapiens fossils found in Morocco ...
https://www.sciencemag.org/news/2017/06/world-s-oldest-homo-sapiens.

The team doesn’t propose that the Jebel Irhoud people were directly ancestral to all the rest of us. Rather, they suggest that these ancient humans were part of a large, interbreeding population that spread across Africa when the Sahara was green about 300,000 to 330,000 years ago; they later evolved as a group toward modern humans. “H. sapiens evolution happened on a continental scale,” Gunz says.
Support for that picture comes from the tools that Hublin’s team discovered. They include hundreds of stone flakes that had been hammered repeatedly to sharpen them and two cores—the lumps of stone from which the blades were flaked off—characteristic of the Middle Stone Age (MSA). Some researchers thought that archaic humans such as H. heidelbergensis invented these tools. But the new dates suggest that this kind of toolkit, found at sites across Africa, may be a hallmark of H. sapiens.

(dhw: Then maybe one factor in sapiens' brain expansion really was new tools. There is certainly nothing here to damage my theory.)

The finds will help scientists make sense of a handful of tantalizing and poorly dated skulls from across Africa, each with its own combination of modern and primitive traits. […].
The connections among these skulls and the appearance of MSA tools across Africa at this time and possibly earlier shows “a lot of communication across the continent,” Brooks says. “This shows a pan-African phenomenon, with people expanding and contracting across the continent for a long time."

No sudden leap from nowhere. As regards stasis, please explain why, in your own theory, your God stepped in one night 315,000 years ago to give some Moroccans bigger brains (with unnecessary 150 cc), skulls and pelvises, only for them and their descendants to do nothing with them for the next 270,000 years.

dhw: Now please tell me what has changed in my theory.

DAVID: Nothing. That is exactly my point. You talk around my objection while changing nothing. Where is the refutation of my point? Where is the sapiens' implementation that cause the expansion?

You wrote: “your changed theory is consistent…” What change? And NOBODY knows what caused the expansion, but new artefacts might have been a factor.

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. […]

dhw: […] 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?

DAVID: I don't know where to begin. The folded cortex of the forebrain did lots of changing as we learned to think with it. Language, as it developed required Broca's area to complexify. [Followed by more examples of how new requirements changed the relevant sections of the brain.]

My point was that the brain itself was not reorganized. I asked: do you think the cerebellum became the cerebrum. The different sections remained the same, but every new activity required new complexifications, some of which resulted in the superfluity of certain cells, which were discarded. None of this flannel about them being “used in the plastic reorganization of our brain to fit our new uses and needs”. Your list confirms that the brain changes IN RESPONSE to new requirements, and my theory is still that the same process would have applied to earlier brains, whether the changes were complexifications or expansions.


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