Evolution and humans: big brain size or use (Evolution)

by David Turell @, Sunday, June 11, 2017, 18:54 (549 days ago) @ dhw


dhw: The claim that your brain transmitted to you what happened during the NDE was clearly topsy-turvy, since you/your consciousness had the experience and your brain wasn’t even there.

Again you do not understand. My consciousness returns to my brain which is now again functional and the two entities interact and my brain now informs me of the NDE experience which the consciousness memory contains.

dhw: However, the major problem was your statement that “a larger brain allowed a more complex use of consciousness and therefore allowed complex conceptualizations to appear.” This is somewhat ambiguous, but you have proposed that your God enlarged the brain and only then could humans come up with more complex concepts. That is the nub of this discussion. I would propose a different interpretation of “allow to appear”. Concepts are the product of the me/consciousness entity. That is clear from your view of the afterlife. But in order for them to “appear”, i.e. to take on form in the shape of words, actions, inventions, books etc. in our physical world, they require a brain. And so complex conceptualizations demand changes to the brain. It is not the pre-existing larger brain that allows me/consciousness to think new thoughts; it is new thoughts that demand a larger brain so that they can be transformed into sensory reality.

Please see my discussion below. I have approached hominin brains as athletic brains solving the problems of survival as stone age hunter gatherers. The frontal and pre-frontal lobes are the conceptual areas, the rest of the brain is sensory and athletic. We got the big front end and started really using it 11,500 years ago.


DAVID: The use of the big brain had to learned and its use in conceptualization exloded in the past 12,000 years, and only then did the brain shrink.

dhw: I agree: consciousness/the self learns to use the brain. And so I would start with the brain, not the big brain. As consciousness increased, pre-humans and then humans learned to use their brains, which expanded in accordance with new demands (= concepts conceived by consciousness). 200,000 years ago, the brain reached its big brain maximum. An explosion of concepts 12,000 years ago required restructuring of the brain, but as it could not expand, the restructuring had to be internal complexification (rewiring), which actually reduced the necessity for “size”.

DAVID: Right. The big brain of 200,000 years ago was not used like recently. Therefore when it appeared, it had lots of useful parts that had to learned to be used, specifically the frontal and prefrontal areas, which were the areas that had grown. The body function areas, the motor areas, the sensory areas, etc., were all in full function. Even now adolescents don't fully learn how to use those prefrontal areas until they are in their 20's.

dhw: We seem to be in agreement and yet not in agreement! Our fellow animals also have the areas you’ve listed, but presumably 200,000+ years ago we were already more self-aware and inventive than they were. (I’m again thinking of artefacts that require complex conceptualizations.) This is why I start with the brain and not with the larger brain. Conceptualization changes the brain. The brain does not anticipate conceptualization, and so pre-sapiens enlargement took place in stages, as needed by conceptualization, before it reached its maximum size. For 190,000 years, the maximum size could cope with any new concepts (you tell us there weren’t many), but then came the explosion and so in came densification.

Generally we are close in your discussion. What I'm trying to get you to recognize is where brain growth occurred (frontal conceptual area), but was not actively used until recently and the brain densified and shrunk. Size first use second.


dhw:You claim that brain enlargement preceded conceptualization, but shrinkage denotes that rewiring replaced enlargement, and we know rewiring follows on from conceptualization. Your scenario therefore has restructuring (enlargement) followed by conceptualization; then you have conceptualization followed by restructuring (rewiring) – a reversal of the process.
DAVID: Exactly, and that is another reason I think evolution is over. The past had the brain enlarging for improvement as we went from hominin to Homo. Now with full size it shrinks as necessary for improvement.

dhw: Whether evolution is over is another matter altogether, but I agree with the rest. However once more: if we are to be consistent (i.e. without the extraordinary reversal explained above), the enlargement takes place in response to conceptualization and not before it. Shrinkage is only a side effect because of the efficiency of densification, which just like enlargement occurs as a result of new concepts. But I like the word “improvement”, since I would regard this as just one example of how evolutionary complexity occurs because of the drive for improvement and not just for its own sake.

200cc H. sapiens growth while working on the basic elements of survival. Not much drive for enlargement. Robert Wright's two books: Non-Zero and The Moral Animal which study mental development in Hunter-gatherers have deeply influenced me about survival and group dynamics development. All learned in the first 190,000 years before real civilization appeared. Size first, use second.


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