Human evolution; savannah theory fading (Introduction)

by dhw, Friday, July 15, 2022, 11:32 (623 days ago) @ David Turell

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.

DAVID: 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.

You persist in starting in the middle of an ongoing process. The ability to adapt has been present since the first ancestors! Each expansion is the result of a new adaptation/innovation. Erectus’s brain started at, say, 850 cc, and – as you yourself have pointed out –it enlarged “as new experiences occurred”. That same process would have led earlier to the 850 cc with which erectus began. Once more: I propose that new experiences CAUSE enlargement, and the brain does not enlarge in anticipation of new conditions it has not yet encountered!

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

And since your God apparently only wanted to design sapiens and his brain, this is part of the theory that “makes sense only to God”. But you call it “reasoning”.

dhw: 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.

DAVID: 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.

Thank you for repeating my own theory. I have no objection to the theory that if God exists, he would have designed the plasticity of cells, without which evolution – including that of the brain – would not have been possible. I only object to your theory that brain changes and all other evolutionary changes took place in anticipation of conditions/requirements that did not yet exist.

DAVID: God never miscalculates, and your comment shows how you view God in a noxious disparaging way.

I do not believe that God would have given us a brain bigger than we needed! But that was the disparaging implication of your insistence that he initially gave us an “oversized” brain. My version is that the brain initially expanded because the new cells were needed to meet new requirements. It was not “oversized”, and cells only became redundant because of the increased efficiency of complexification. There is absolutely nothing noxious or disparaging about God in any of my theories. But I admit to being disparaging about theories which suggest that your God had only one purpose and therefore deviated from his purpose in order to achieve it. I am also disparaging about your theory that evolutionary changes take place in anticipation of requirements that do not yet exist. It seems to me to be pure common sense that such changes would take place IN RESPONSE to new conditions/requirements, and not before these came into existence.


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