Human evolution; savannah theory fading (Introduction)

by dhw, Saturday, July 16, 2022, 08:21 (861 days ago) @ David Turell

DAVID: [The article] makes clear an Erectus brain developed in Africa allowed them to migrate and adapt easily everywhere else. Clearly brain first.

dhw: 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: Erectus with an 850cc brain appeared in Africa first. It was that brain's thinking capacity which allowed/stimulated Erectus to migrate all over the Earth. Brain first, actions followed! Nothing could be clearer.

But how did erectus get his 850 cc brain in the first place? You have pointed out that during his migrations his brain enlarged “as new experiences occurred”. If homo habilis was erectus’s immediate ancestor, and his brain capacity expanded from 650 to 800 cc., you can see a progression “as new experiences occurred”, and the expansion to erectus’s initial 850cc would have followed the same procedure. And when he migrated, there were more new experiences resulting in more expansions. New experiences/requirements first, then expansion as a result.

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

dhw: 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”.

DAVID: We both offer reasons about God, but it seems only yours are allowed to be reasonable.

It’s not a question of being “allowed”. You can’t find any logic in your theories, which make sense only to God, i.e. not to you. What logical flaws have you found in my theories?

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. bbbAs the brain reorganized in complexification it discarded unnecessary portions.

dhw: 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: What you do not understand is a proper designer designs for future use. All part of design theory.

I am not denying that once the designs had proved successful, they would then be used in the future. But for example, I do not believe pre-whale legs were turned into flippers before the animals began to explore life in the water. And I would propose that the invention of the spear would have required major new skills and hence major changes to the brain, rather than the brain changing in anticipation of the making and use of the spear.

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

dhw: 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. […]

DAVID […] And I would note, your comment about brain size does not answer the issue that our brain shrunk with use, therefor it obviously was oversized at the start.

In my theory, it would not have been oversized at the start. That would indeed have made it a miscalculation if your God did it! The cells that resulted in expansion would have been needed to meet some new requirement. But later, as further expansion might have caused problems, complexification took over almost completely, and it was so efficient that some cells which had been needed earlier then became redundant.

DAVID: You have no understanding that God never deviates from His purposes. You just are confused as you try to outguess God's reasoning. See the other entry about staged evolution and how a designer works with it.

I remain flummoxed by your insistence that he had only one purpose (to design sapiens plus food), and proceeded to design countless forms and foods that had no connection with sapiens but these were not deviations. I don’t know how this is meant to prove that your God dabbled with brains and bodies before changes were required, but I do sometimes have difficulty following your train of thought!