Brain expansion: different theories about rapid expansion (Evolution)

by dhw, Tuesday, September 29, 2020, 14:24 (26 days ago) @ David Turell

dhw: Nobody knows why earlier brains added neurons. The modern brain is capable of adding neurons when necessary. It is perfectly feasible, then, that earlier brains also added neurons when necessary. The fact that the modern brain has ceased to expand, and now complexifies in order to meet new requirements, does not mean that the mechanism for expansion in the past only applied to the hippocampus!

DAVID: If one believes in common descent, new advances must mirror past processes. For me our brain acts as old brains did. Which means new neurons added only to the hippocampus. Your thought is just wishful thinking.

We know that various sections of the brain expanded in the past. We know that one section has expanded in the modern brain. Somehow this proves to you that other sections could not have done the same in the past, and therefore God stepped in and added the new cells. Perhaps we should leave it at that.

dhw: And so to stasis. My proposal: 1) brain expanded by meeting unknown requirement. 2) No new requirements for 280,000 years. No change in brain. That means STASIS. 3) New requirements after 280,000 years coincide with changes to the brain. You can hardly have a clearer, more logical sequence. Your belief: 1) God performs operation on Moroccans. 2) Moroccans do nothing with new brain for 280,000 years. QUESTION: Why would God expand brain 280,000 years before it was needed? Answer: to “learn how to use it” but “little was done with it”. Sorry, but I don’t think I’m the one who is “struggling with the issue”.

DAVID: All depends upon point of view. I start with God running the show and my theory follows easily from that decision.

You were the one who brought up the subject of stasis. If you think your proposed explanation follows easily, so be it.

DAVID: You are searching vainly for a natural cause of brain enlargement, asana God. Your 'unknown requirement' is pure invention. All pre-Homo sapiens species fossils are aged with new artifacts, but not us!!! Fact, not imagination.

My explanation is not “sans” God, as you well know. I am an agnostic. My explanations always include the possibility of God. But that does mean that God has to preprogramme or dabble every evolutionary development, natural wonder etc. in the history of life. As regards fossils and artefacts, here is a website that may interest you.
https://www.britannica.com/science/human-evolution/Increasing-brain-size

QUOTE: Because more complete fossil heads than hands are available, it is easier to model increased brain size in parallel with the rich record of artifacts from the Paleolithic Period (c. 3.3 million to 10,000 years ago), popularly known as the Old Stone Age. […] Hominin brain expansion tracks so closely with refinements in tool technology that some scholars ignore other factors that may have contributed to the brain’s increasing size, such as social complexity, foraging strategies, symbolic communication, and capabilities for other culture-mediated behaviours that left no or few archaeological traces.

Please note the reference to contribution to brain size – as opposed to the idea that the brain expanded in anticipation of these new uses.


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