Brain expansion (Evolution)

by David Turell @, Wednesday, July 15, 2020, 15:12 (24 days ago) @ dhw

DAVID: In life the soul and brain are totally linked. The immaterial soul must use the neuron networks to retrieve memory, to receive sensory information, and to develop abstract thought, which thought can only be as abstractly complex as the neuron networks allow. This fits the slowly advancing of human forms/brain enlargement over time associated with more advanced artifacts.

dhw: We agree that the dualist’s immaterial soul must use the material brain, but why is its abstract thought limited to the capacities of the neuron network? Once again you refer to artefacts, and so once again let’s use them as an example.

Simple analysis. Bigger more complex brains are related directly to advances in artifact complexity. Complex brain allowed the appearance of more complex thought by the soul.

dhw: I don’t understand your answer, but I presume it is a cover for your not knowing why the ancient brain could not have had the same mechanism as the modern brain.

I assume earlier brains had some degree of complexification.


dhw: You are right – my reply concerned the history generally, and not sapiens’ history. My apologies. But I have already given you the answer umpteen times. We do not know what new requirement resulted in the final expansion. But I propose that the sapiens brain stopped expanding because if it had expanded any further, this would have necessitated major changes to the whole anatomy.

DAVID: Skull size no problem. Our brain was sizeably bigger (about 150 cc) before the shrinkage, with no anatomic problems. Could be easily added back, if necessary, but isn't. Your anatomic problem is not reasonable.

dhw: My “anatomical problem” explains why the brain and skull stopped expanding after reaching that size! Once complexification had taken over, the brain eventually shrank because of its efficiency, although according to you, there were also minor expansions. So why would the brain as a whole start expanding again to fill the gap once complexification had proved so efficient? Do you expect it to fill the gap and then revert to complexification because it’s gone back to the size which won’t allow further expansion?

More talk around your original explanation that anatomically the head could get too big!!!


DAVID: You have agreed to a stasis period. That destroys your idea that compelling ideas in a previously smaller brain demanded enlargement for implementation. Where is the implied immediate implementation? No where. Delayed for over 200,000 years.

dhw: You seem never to have understood the point I keep bolding. We don’t know what “compelling ideas” demanded enlargement for implementation. We took artefacts as an example, because they are the only concrete evidence we have from the past. The trigger could have been new requirements through local environmental changes, new discoveries, new developments within a social structure. None of us were around at the time, and none of our ancestors knew how to keep a diary! As for stasis, again you persist in ignoring my previous answers. Once the unknown cause had required expansion, there were no new ideas or discoveries or developments that would have required expansion. This applies to pre-sapiens AND to sapiens. There were always periods of stasis. In sapiens’ case, the stasis ended when some clever folk did have new ideas, but for the reason I have given, the brain did not expand – it complexified.

I fully understand your approach. The bold is irrational. We don't have to know which idea did it! Your unknown (natural) cause (in color) was an impelling idea in the earlier brain. Are you now going to retract that theory? It seems so. What drives expansion naturally, if anything. No evidence in sapiens brain history.


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