Brain expansion (Evolution)

by dhw, Sunday, July 12, 2020, 10:11 (110 days ago) @ David Turell

DAVID: You have abandoned your original thought that an idea in a previous brain forced the new expansion as it was implemented by the new brain. Progress!!

dhw: How the heck to do you arrive at that conclusion? I am saying that I do not know what new “idea” triggered the expansion! We took the spear as an example, because artefacts are the only concrete evidence we have. The trigger could have been changes in the environment or new discoveries or experiences that forced the existing brain to implement new ideas concerning modes of living. Whatever may have been the new “idea”, it would have arisen originally in the old smaller brain, and its implementation would have exceeded the capacity of that brain’s complexification and so would have necessitated additional cells.

DAVID: Still defending your natural view of expansion. Fine. We clearly disagree. I'll stay with God who decides when in evolution a larger brain will appear. All we know about human brains is they shrink when heavily used, after having enlarged at first in areas that provide the soul with more complex conceptual thinking areas. That is basically where all enlargement takes place from Lucy-likes and onward.

Of course I’m still defending it. We know that the modern brain stopped expanding (I suggest that this was because further expansion would have required major adjustments to the anatomy), complexifies in response to thought, certain areas expand in response to thought – but not enough to require overall expansion – and certain areas have shrunk because of the enhanced efficiency of complexification, which made those areas redundant. It is therefore perfectly feasible that in former times brains also complexified in response to thought and expanded in response to thought. They would not have shrunk, because the existing capacity for complexification was inadequate to cope with the new thoughts which required implementation.

DAVID: Skulls and brains shrink is the only example we have in sapiens even if neurons are added in the hippocampus. It is all part of plasticity and complexification. I suspect, as stated before, both processes were present to small degrees in earlier hominin/homo brains, neither of which would enlarge brains.

Same again. Yes, it is all part of plasticity, added neurons in the hippocampus are an example of expansion, and we agree that both processes (complexification and expansion) would have been present in earlier brains. But my proposal is that when their capacity for complexification was insufficient, expansion took over. In the modern brain, when greater capacity is required, enhanced complexification has taken over, and – for the umpteenth time – you have agreed that shrinkage is the result of complexification’s increased efficiency. I still don’t know why you think your God could not have given earlier brains the same mechanism for autonomous complexification and expansion as the one you recognize as being present in the modern brain, although you refuse to countenance the possibility that the mechanism might be cellular intelligence.


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