Evolution and humans: big brain birth canal (Evolution)

by dhw, Saturday, October 27, 2018, 09:47 (327 days ago) @ David Turell

DAVID: You have not explained how the cell communities cooperate, but just stated it as if it were fact. It is not an answer to how do separate individual organisms communicate and coordinate genome changes"? As for Dad, his genes dictate in part the fetal size, including the skull.

dhw: Are you saying that your body does NOT consist of cell communities? If you agree that it does, how do you think your homeostasis works, if not by achieving a cooperative balance between all of them? […] Yes, the genes of Mummy and Daddy both played their part in making the big-headed fetus, but I doubt very much that Daddy’s genes dictated the expansion of the birth canal.

DAVID: Neatly avoided the issue that three separate individuals had to coordinate the result. Of course body organs and their cells cooperate, totally beside the point. You don't have a natural answer, just avoidance.

I don’t see how Daddy’s genes would have dictated the expansion of the birth canal, but of course the fetus and Mummy must cooperate, and the cooperation between cells is entirely to the point. I’m glad you now acknowledge that it is a fact. Neither of us is in a position to explain the details or the timing of the process through which the cell communities cooperated to expand brain, skull and birth canal, but however it happened, you say your God preprogrammed/dabbled the cooperation, and I propose (theistic version) that he gave the cell communities the ability to work it out for themselves – as we assume they do for minor adaptations. Same process: different hypotheses concerning how your God may have done it.

DAVID: God took the pre-humans out of the trees. He also changed the codes for birth canal size for everyone.

dhw: It’s a lovely image: one by one, your God psychokinetically forces a group of primates to climb down (leaving lots of other primates up there, wondering what’s going on – or do you now subscribe to my hypothesis of an isolated group (see “foraminifera”)? – and one by one he fiddles psychokinetically with each female’s birth canal, so that it will accommodate the larger brain in the larger skull, which he has also engineered psychokinetically. And let’s also remember that according to you his prime purpose is the brain of Homo sapiens, and this lot are just PRE-sapiens. So for some unknown reason he’ll let this lot (and a few other lots) do their own thing for hundreds of thousands of years, and then he’ll presumably do another dabble, or changing of the codes, until he gets what he’s always wanted. Truly your God works in mysterious ways his natural wonders to perform.

DAVID: Answered in the other thread with my comments about Lucy, the transitional form, with the same tiny brain as her ape dwelling cousins. Certainly God got his desired big-brained human by enlarging the birth canal.

I would have expected it to be the other way round: that the big-brained human fetus required the enlargement of the birth canal, but if you think your God enlarged the birth canal and this caused the expansion of the brain, so be it. I don't know why you think the transitional form proves that your God preprogrammed or dabbled the anatomical changes in advance.

DAVID: Any natural trial and error attempt would result in a series of still-borns or necessary microcephalics.

I can’t imagine that the skull and the birth canal expanded overnight, but as above, neither of us can possibly know the details or the timing.

DAVID: And why suddenly worried about time intervals? You know full well that single-cells started life 3.5+ billion years ago. It is obvious evolution takes lots of time, and you now that. God is mysterious to your because of your overanalysis of his humanism. He is His own person, not the one you want Him to be.

The mystery is why your God would have personally preprogrammed or dabbled all these different hominins (not to mention whales and elephants and the duckbilled platypus) if his prime purpose was to produce the brain of Homo sapiens. I am not in the least worried about time intervals. I am worried about the illogicality of your suppositions, and I do not accept that we must abandon all sense of logic just because you would rather believe your God doesn’t think like us. Maybe he doesn’t think like you, and your suppositions are inaccurate, and his purpose and method are perfectly in keeping with human logic.


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