Brain expansion: different theories about rapid expansion (Evolution)

by David Turell , Thursday, September 03, 2020, 18:56 (1540 days ago) @ dhw

DAVID: Once again you have our brain inexplicably expanding. Areas in our brain make tiny enlargements for specialized tasks, nothing more. No evidence for your theory.

dhw: I have provided a theoretical explanation for the unexplained expansion, and the fact that our brain – which no longer expands – still makes small enlargements may be regarded as evidence that the brain is capable of making enlargements. And the evidence for your divine dabble is….?

DAVID: The obvious need for a designer.

dhw: I don’t have a problem with your argument that the mechanism must have been designed, and now that you have confirmed that this mechanism for the brain’s adaptability is autonomous, I doubt if even you would believe that the same mechanism could not have existed in pre-sapiens brains.

I'm sure it did, but the small use by early hominins did not result in shrinkage as now.

[…]
DAVID: Your comment precisely ignores a tenet of evolutionary theory that present organs are built upon the attributes of past designs. What our brain does is an example to what past brains did, perhaps without the shrinkage.

dhw: Thank you for this very clear support for my theory. Our brain, as you have told us, “has the adaptability to react to any and all physical and mental and emotional demands we place on it.” It even adds a few cells when necessary. (Shrinkage results from the enhanced efficiency of complexification, and would not have occurred if the requirement was for new cells.) According to my theory, present organisms are built upon the attributes of past designs. There is no sudden leap – as if your God had performed an operation to introduce new brains, skulls and pelvises. [David's bold] Our brain does what past brains did, and so past brains would also have complexified and expanded as a REACTION to new requirements, as summarized so perfectly by yourself in the bold above.

DAVID: Glossing over the multiple problems of new baby skull size, pelvis birth canal size, and Dad's contribution genetically doesn't solve or answer in any way your skull/brain growth theory. The sentence after the bold ignores all of it!! All we have as evidence is 200 cc jumps in brain size and better artifacts with the human fossils. I have my designer as the best answer I can think of.

dhw: We have dealt with this before! You insist that all the changes must have happened simultaneously, whereas I propose that the skull would have responded to the expansion of the brain, and the pelvis would have responded to the expansion of the skull. All cell communities have the same ability as the brain to adapt by reacting to new requirements, but this does not happen overnight! Firstly, we can’t expect a complete, inch-by-inch fossil record of all changes to brain, skull and pelvis. Secondly, there may have been countless deaths in childbirth before the cell communities could adjust themselves to the new size. Even today, childbirth is an extraordinarily painful procedure. Thirdly, Dad’s contribution would not have suddenly changed from one generation to the next! And fourthly, your “designer” is not the subject under discussion. For the sake of argument, I am accepting his existence, and we are discussing the likeliest explanation for the brain’s expansion. His invention of a mechanism enabling intelligent cell communities to cooperate in adapting organs and organisms to meet new requirements would provide an explanation for brain, skull and pelvis expansion as well as for every innovation, adaptation, econiche, lifestyle, strategy, natural wonder etc. in the history of life.

The designer is under discussion because I believe God is the master designer for all speciation. The enlargements of 200 cc are not tiny adaptations. 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. 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. New body designs need careful guiding by God. And you have never explained how cellular intelligence appeared naturally in cells, without God help. I know you have no answer other than the evidence cells react intelligently.