Human evolution; savannah theory fading (Introduction)

by dhw, Wednesday, August 03, 2022, 11:23 (841 days ago) @ David Turell

Brain expansion

DAVID: We've discussed this in the past and I've said all previous brains were similar and all had free will.

DAVID (July 19th): We came with extra neurons in our brain so we could use our brain as we wished which gave us free will. (dhw's bold)

dhw: If the extra neurons gave us free will, then clearly you think our precursors could not have had free will, but I’m pleased to see that you are now disowning this theory.

DAVID: I don't know how you derived that weird interpretation.

From your statement bolded above. I’m glad you now agree that it is weird.

DAVID: I doubt they shrunk as ours has. God added those extra neurons to allow us freedom of brain development as we learned to fully use it.

dhw: There would have been no reason for them to shrink. They would have expanded in order to meet new requirements. I have no idea what your second sentence means. Do you think the gradual increase in earlier brain sizes and accomplishments indicated that there was no “freedom of brain development”? In your next comment, you agree to my explanation of shrinkage, so why are you inserting this woolly explanation here?

DAVID: If you have a brain that is little used compared to capacity, as new concepts appear that is 'learning to use it'. That is a 'freedom of development'.

I propose that our additional cells followed exactly the same pattern as before: all our ancestors had “freedom of development” – which resulted in the addition of cells when needed! But for reasons unknown, we reached a stage at which complexification took over from expansion and proved so efficient that some cells became redundant. You agree, so what’s the problem?

DAVID: The problem is your interpretation of the original added neurons and how they became present. There is no known required mew complex usage that drove their appearance from a natural cause, considering the simplistic lifestyle of our immediate predecessors.

dhw: Nobody knows precisely what new usages caused new cells to be added to any of the brains from our earliest ancestors onwards. But in some cases they appear to have coincided with changes such as bipedalism, new artefacts, new lifestyles (hunters/gatherers)….It is not unreasonable to suppose that something new caused the sapiens expansion, as opposed to your God performing an operation on a group of sleeping Moroccans to prepare them for innovations that wouldn’t take place for a couple of thousand years.

DAVID: Same old commentary. What new single event required such a jump in brain thought ability?

You are asking me to solve mysteries which nobody else has solved. But I have given you examples of past events that might well have required additional cells, and so it is not unreasonable to suppose that the same process would have repeated itself.

Braincase size unchanged

QUOTES: "The cranium, or braincase, of early modern humans dating back 200,000 years isn’t much different in size from those today, but has a significantly different shape, suggesting that the brain has become rounder over time."

"The leading hypothesis is that changes in behaviour, such as the development of tools and art, caused the shape of the Homo sapiens brain to change and, in turn, the skull that protects it[/b]." (David’s bold)

DAVID: so, the brain shape changed, undoubtedly due to our new uses of it with complexification and shrinkage as a result. No evidence for dhw's weird anatomic theory that a larger skull could not be accommodated.

dhw: The article tells us that the size remained unchanged! How does that come to mean that a larger skull COULD have been accommodated?

DAVID: The Neanderthal's accommodated a larger brain and skull. That destroys your accommodation theory.

You tried to use the article as proof that a larger size could be accommodated, but it shows clearly that it was the shape and not the size that changed. Neanderthals were a different build from us, and their brain size was not massively greater than ours, and may even have been the same size as those of their contemporary sapiens. But again, you are asking me to solve problems that nobody else has solved. And you have not yet given us your own theory as to why our brain stopped expanding and reverted to enhanced complexification instead. Please tell us.