Brain complexity: learning new tasks (Introduction)

by dhw, Sunday, December 03, 2017, 13:29 (2547 days ago) @ David Turell

dhw: In sapiens, it has shrunk thanks to the efficiency of complexification. In pre-sapiens it kept reaching points at which it had to expand, and since it already had that ability, it did not need God to do the expanding. (But he may have designed the ability.)
DAVID: Then you will not accept my theory that pre-sapiens brains had the expand/contract mechanism. One of us is correct. No evidence can be available.

According to my hypothesis pre-sapiens brains most certainly had the mechanism for expansion, and eventually expanded by approx. 200 cc whenever the process of complexification could no longer cope with new demands. Whether, prior to that moment, they also contracted is irrelevant, but they may have done so. Our question is why the brain expanded permanently, and so if it did contract, the rate of contraction (through complexification) was eventually not sufficient to cope.

dhw: With pre-sapiens, once complexification had exhausted its abilities, the implementation of the new concept (artefact) would only appear when the brain had finished changing itself (i.e. expanding). And so of course the artefacts are only found alongside the hominin whose brain had finished changing itself.
DAVID: This last paragraph of yours is very close to my view, except for the cause of expansion. If habilis has an idea for spears, the idea is immaterial. No brain change. Once he learns to knapp flint, attach the stone point to a wooden rod, and then practices throwing it with accuracy, there is no question his brain has enlarged with all the muscle movement and visual coordination involved.

Precisely.The smaller brain produces the concept. The process of implementing the concept, as you have described so vividly, is what enlarges the brain. The brain did not enlarge before the concept and its implementation, so why do you say your view is different from mine?

DAVID: But then the brain complexified and shrank. Based on human athletic training their skulls stay the same size, as in the newly newly trained Italian readers. Small ezxpansion and contraction.

Now you are confining your observations to Homo sapiens. 300,000 years ago the brain/skull reached its optimum size, and so instead of reaching a point where it HAD to expand, it responded to new demands by complexifying (as with the Indian readers), and this process was so efficient that it actually shrank. The mini expansion and contraction takes place as the brain restructures itself, and this may well have also been the case in pre-sapiens until it required permanent expansion, after which the same process would have repeated itself until the next permanent expansion.

DAVID: You have thrown out one of the major tenets of the study of evolution. Improvements build on each other. Sapiens did not invent brain expansion/contraction. Don't you think Neanderthal brains worked the same as ours? Without question, it came from earlier homos' brains. Your first paragraph ignores the sequence of use of the brain: " But you have him doing it BEFORE new concepts made it necessary, whereas I have hominins doing it WHEN it was necessary." Concepts do not enlarge brains. Only functional use of new practices does.

When have I ever said improvements don’t build on each other? Of course they do. And I’m delighted to see you at last agreeing that improvement is one of the major driving forces behind evolution. In concrete terms: simple artefacts needed expansion 1. Better artefacts needed expansion 2. And when have I ever said sapiens invented the process? Complexification would have taken place in pre-sapiens’ brains just as it does in ours (maybe with mini expansions and contractions, as discussed in our last exchange), but when demands exceeded the capabilities of complexification, they expanded permanently. In us further expansion was not possible and so complexification took over. You have finished by triumphantly repeating and supporting my case against your theory! Brains were not enlarged BEFORE the concepts and the implementation of the concepts, as you have insisted until now. The small brain produced the concepts, and the implementation caused the enlargement.