Human evolution; savannah theory fading (Introduction)

by David Turell , Thursday, July 14, 2022, 17:54 (861 days ago) @ dhw

DAVID: I agree the Erectus brain increased over time, but a key thrust of the article is Erectus migration from Africa all over the world, as I stated above and from the article:

dhw: I can only comment on the material you present to us. However, the extra material about erectus makes no difference to the argument. He was already “upright”, and “the first expansions of our ancestors beyond Africa have often been associated with periods of climate change that would have resulted in the extension of grassland ‘corridors’ out of Africa.” This clearly suggests that changes in living conditions coincided with changes in behaviour,

I'm sorry I confused you. I suggest you digest the entire article to follow my points. It makes clear an Erectus brain developed in Africa allowed them to migrate and adapt easily everywhere else. Clearly brain first.

DAVID: The brain came first and the migration afterward and did enlarge within the same
species as new experiences occurred.

dhw: The brain expands when it has to cope with new experiences that exceed its existing capacity. From the time when our earliest ancestors descended from the trees, there was a continuous expansion in response to new experiences. Yes, erectus came long after those earlier times and expansions, so when he migrated, he already had a bigger brain than his own ancestors, and then new experiences resulted in his own brain expansion. Thank you for confirming the sequence of the process: new experiences result in expansion.

You and I have no factual evidence about what caused brains to enlarge. I follow the reasoning God designed each explansion.

DAVID: Note! In contrast to our brain shrinking with new complex advanced uses. Why? I view us as a completed endpoint while Erectus was a work in progress as God designed it.

dhw: This is what I wanted to avoid. We have been over it again and again. Why would your God have given us a brain bigger than was needed? A miscalculation? I propose that our brain had reached a point beyond which further expansion might have caused problems in the rest of the anatomy, and so the process of complexification (which had always existed) took over completely, and proved so efficient that some existing cells were no longer necessary. Hence shrinkage.

And my more logical view of God is our oversized brain allowed for more efficient plasticity in handling the many new uses of complexity we had for our brain. As the brain reorganized in complexification it discarded unnecessary portions. God never miscalculates, and y our comment shows how you view God in a noxious disparaging way.