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

by dhw, Monday, June 26, 2017, 13:36 (2705 days ago) @ David Turell

dhw: “Size first, use second” is fair enough, since we now know that by use you mean nothing more than material implementation of immaterial thought.
DAVID: Size first, use second is exactly as you now recognize I mean it. Brain growth is not from attempted conceptualization beyond the capacity of a particular sized brain.

Once again you are equivocating. It is not attempted conceptualization that would cause brain growth but attempted material implementation of new concepts. In this dualistic hypothesis, the existing brain is not capable of implementing the concept of the spear, and so it has to add to its capacity. Concept first, brain growth second, implementation third.

dhw: She starts with a brief sideswipe at religion, but there’s no mention of God’s planning/dabbling (so I don’t know about “all” your theories), or of random mutations, or of cell communities working it out for themselves. Her causal theory stops at nerves and the base of the skull.
DAVID: She shows pre-planning in the small changes. She is a scientist, not a theist. I'm the theist interpreting her work.

The small changes are, of course, very interesting in view of your hostility to Darwin’s gradualism (though in general I agree with you that saltation seems far more likely in most cases of innovation), but “pre-planning” is entirely your theistic interpretation of her thesis.

MALASSÉ: These embryological details have dramatic consequences. The emergence of upright hominid posture need no longer be linked to habitat changes. Its origin must be attributed to the increasing complexity of the nervous system. The embryonic body plan was reorganized through a series of threshold effects which are still in evidence in every human embryo.
dhw: And this is where, in the context of our discussions, it might have been interesting to know what she regards as the cause of the increasing complexity and the resultant upright posture.
DAVID: I don't know if she has religious thoughts, but her whole work smells of teleology as humans appear in their earlier forms, and previous monkey forms have minor changes with no immediate benefit, but are obviously preparatory for bipedalism.

I can’t whiff any teleology in her work, and you are simply guessing that the changes had no benefit. Malassé actually suggests that the changes may denote “conceptual and creative innovations well before homo habilis”, so you certainly can’t derive your assumption from her work. The changes clearly mark transitional stages on the way to full bipedalism, but in the context of your belief that your God’s one and only purpose was the production of Homo sapiens, that only raises the question of why the heck he didn’t just get on with it instead of messing around with all these itsy-bitsy twiddles to the position of the skull, and all these different hominins, and all these different pre-whales. What happened to the good old saltatory method? No need to answer. I know it doesn’t make sense to you either, but in your own immortal words: “If it’s God’s method, it does not have to make sense.”