Revisiting language and brain expansion (Evolution)

by David Turell @, Sunday, February 02, 2020, 16:19 (15 days ago) @ dhw

Switched from the Shapiro thread, as the subject suddenly changed!

DAVID: My usual simple answer: your answer skips neatly over the problem of rapid brain enlargement over 2-3 million years to 1,200 from 400 cc originally, which lays fallow until it doesn't as in your comment, "enormous changes even in the last few hundred years" occurs, and then as you agree, it has some small shrinkage. None of the bolded (1) could have happened if the brain wasn't just lying there waiting to be used. And in bolded (2) what 'requirements' made the brain so large in advance of all the uses you so clearly list appearing after lots of time. Your leg/flipper comparison does not fit the big brain story, does it?

dhw: I propose that our earliest ancestors came up with ideas or were faced with new conditions that required more brain capacity than they already had. We know for a fact (though you prefer to forget it) that implementation of new ideas leads to changes in the brain (the illiterate women, taxi drivers, musicians etc.).

You forget I just mentioned that fact in a recent post. And the modern brain has shown overall shrinking, remember.

dhw: Way back when – to give you an example – let’s say some clever clogs got fed up with having to wrestle a bison in order to get some meat, and thought of putting together a sharp piece of stone, a stick, and one of his arms. But this idea required thoughts and deeds never done before, and just as muscles grow with exercise, so the brain expanded with the effort of planning and producing and throwing the first spear.

The biology of muscles allows them to expand to meet the requirements of more work, built in. The brain, a totally biologically different structure with massive use has shrunk. Your comparison does not hold water; it is like comparing oysters to cows.

dhw: Take it from there. The brain expands. And for a while, the expanded brain can cope with all the demands made on it…until someone else produces - or new conditions demand - new ideas it can no longer cope with. More expansion.

This description is totally Darwinian, since it implies bit by bit growth as new needs appear. It totally ignores the 200 cc jumps in size the fossil record exhibits. And how homo lives improves after each jump, as archaeologists show. This is the key issue you constantly evade.

dhw: But eventually the brain expands to a point at which further expansion would unbalance the whole structure, and that is when complexification takes over. So in answer to 1) No, the 1200cc brain wasn’t just lying there to be used. It was being used all the time, unless our ancestors were zombies, but when new ideas or new conditions came along, instead of expanding, it complexified (and eventually shrunk, presumably because complexification proved so efficient). 2) Unfortunately I wasn’t around at the time to know what new ideas or requirements led to each stage of expansion over 2-3 million years – which is nothing in geological time, but a helluva lot in terms of generations of organisms capable of making changes.

Again pure Darwin, bit by bit.

dhw: But we do know from the way the brain works now that it does not change in advance of new ideas and/or requirements; it responds to them. To our knowledge, every adaptation that has ever happened has been in RESPONSE and not in anticipation. The whale story fits the brain story precisely: flippers replaced legs as a result of the pre-whale adapting itself to marine life, and not in advance of it entering the water: anatomical changes are a RESPONSE to new requirements and do not take place in anticipation of them.

The brain working now is at the end of evolution. It is fully done expanding, based on the shrinkage. The idea that the early brains grew to this size under requirement pressures is totally ass backwards, an inverted Darwinian theory. Your bold is discussing minor needed adaptations within species. The brain expansion IS major speciation, and you mix up the two concepts. You cannot make species adaptation into speciation.


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