Brain expansion (Evolution)

by dhw, Thursday, July 16, 2020, 11:41 (1379 days ago) @ David Turell

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?

DAVID: 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.

I don’t disagree with this. Once the brain has expanded/complexified, then of course it will contain more information for the dualist's soul to work with, and will have developed more skills to enable it to implement the soul’s ideas. But this doesn’t tell us why the brain expanded in the first place, and it doesn’t mean that the dualist’s soul cannot have new thoughts using the existing brain!

dhw: 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’s bold)

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?

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

This is not “talk around” anything! Once more, I propose: the brain stopped expanding because a bigger head would have caused anatomical problems. Complexification took over, and was so efficient that the brain shrank. You want the brain to start expanding again because there is now room for expansion (as I have bolded above). Although there are indeed minor expansions, I am asking you why the brain should abandon its successful method of complexification and revert to expansion though it doesn’t need to.

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.

DAVID: 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.

Why is it irrational to say we don’t know the cause of something? Yes, the unknown cause was an impelling idea. Why does that mean I seem to be retracting the theory? We don’t know the cause of speciation, so should we retract the theory of evolution? Nobody knows what drove expansion. Does that mean you are retracting your theory that God did it? All this is a total non sequitur. Sapiens’ brain history offers the evidence that the brain complexifies and expands on a minor scale IN RESPONSE to new requirements. Therefore it is not unreasonable to suppose that the pre-sapiens brain also complexified and expanded IN RESPONSE to new requirements, as opposed to expanding in anticipation of them. But in order to forestall yet more flogging of dead horses, let me repeat: once the brain had expanded, of course it could come up with more new ideas. If it didn’t, there was stasis, both with pre-sapiens and with sapiens.