Brain expansion: different theories about rapid expansion (Evolution)

by dhw, Saturday, September 05, 2020, 10:06 (1322 days ago) @ David Turell

DAVID: …the small use by early hominins did not result in shrinkage as now.

dhw: Of course it didn’t. Shrinkage only occurred when the complexification process proved so efficient that certain cells were no longer needed. Prior to that, the requirement was for more cells, and so my proposal is that the mechanism produced more cells, as it does now when certain parts of the brain require them.

DAVID: The enlargements of 200 cc are not tiny adaptations.

dhw: “We can’t expect a complete inch-by-inch fossil record of all changes to brain, skull and pelvis.”

DAVID: We have gaps in size of 200 cc. the only facts we have to support theory.

Your theory is based on the assumption that the fossil record is complete. Alternative theories may be based on the assumption that the fossil record is not complete. The reason why we can only theorize is that none of us know all the facts.

DAVID: They require the neurons to tell the bone cells of the skull we are going to overproduce the head size in the baby. And some cells in the process must tell the mother's pelvis, change shape and size of the bony birth canal.

dhw: They don’t require advance notice (“we are going to”). The cells in the skull respond to the expansion of the brain, and the cells in the mother’s pelvis respond to the increased size of the baby’s skull. But the latter process will no doubt have taken time, and there may well have been countless deaths in childbirth. Even today the process is extremely painful.

DAVID: All you have done is gloss it over again and offer a sop to a God who gives all cells an autonomous adaptive mechanism under your intelligent cell theory with no basis, when we know molecular errors can occur.

dhw: You wrote: “our brain has the adaptability to react to any and all physical and mental and emotional demands we place on it” and you have agreed that it reacts and adapts without God “stepping in”. The brain is a community of cells, and if he can give those cells the autonomy to react and adapt, why should he not have given the same autonomous ability of adaptation to all the body’s cells? See the errors thread for errors.

DAVID: The brain we got from God was oversized to begin with. Your theory is based on that example and then extrapolated beyond the only facts we have. The complexification mechanism works beautifully as designed. Do you think the pre-sapiens neurons knew enough of future use by sapiens to have self-designed by themselves such a mechanism for future use? I sure don't.

You seem to be obsessed with shrinkage, which is totally irrelevant to my theory! For the umpteenth time, my theory is based on the known fact that the modern brain – as you have confirmed over and over again – has an autonomous system enabling the brain to change IN RESPONSE to new requirements. These changes are mainly in the form of complexifications, but there are also examples of EXPANSION, and so it is perfectly feasible that the same autonomous system engineered complexification and expansion in pre-sapiens brains. And in answer to your question, no, I don’t think pre-sapiens neurons knew about future use! I think pre-sapiens brains expanded in order to meet new requirements – just as sections of the modern brain have done. It is you who initially harped on about your God “anticipating” how the enlarged brain would be used, but you then got in a complete tangle over what exactly he anticipated. I’m pleased to see you have now dropped that subject.