Evolution and humans: big brain birth canal (Evolution)

by dhw, Tuesday, October 30, 2018, 09:24 (45 days ago) @ David Turell

DAVID: Dad's genes couldn't have any control over the canal. THAT is my point about his part of the triumvirate involved. And how do Mum's genes know the baby was killed by too much squeeze? You have no answer to the obstetrical dilemma.

dhw: You wrote that “three separate individuals had to coordinate the result” – the result being the expanded birth canal. I have pointed out that Daddy’s genes did not coordinate the expanded birth canal, and I have agreed with you that baby’s genes didn’t either, so the three separate individuals did not coordinate the result, and we are left with Mummy’s cell communities doing it all by themselves (using their possibly God-given intelligence). I’d call it adaptation to new circumstances. But I know you prefer the hypothesis of your God fiddling around with a collection of pre-human birth canals to prepare them for when he fiddles around with a group of pre-human brains and skulls.

DAVID: You have succeeded in talking all around the problem. Yes there are three individuals
involved, but the DNA of none of them can can solve the problem since they are not directly connected in any way.This cannot be solved by hit and miss attempts at enlarging the pelvic outlet if the skull has enlarged. Both have to be simultaneously changed! Only design fits and tiny evolving alterations of one or the other will simply end up in brain-dead babies.

You have succeeded in a complete reversal of your argument: first, "three separate individuals had to coordinate the result" (the expanded birth canal), and now only the mother can do it. Then your God mysteriously "got his desired big-brained human by enlarging the birth canal". We are not talking about hit and miss. If the fetus is larger, the birth canal must obviously expand. Nobody knows how these changes took place, but you expect me to give you the details. Common sense suggests to me that the skull had to expand in order to accommodate the expanded brain, and the birth canal had to expand in order to accommodate the enlarged skull of the fetus, but if you believe your God popped in and fiddled with a group of prehumans’ birth canals in order to get his bigger-brained humans, or fiddled simultaneously with all their brains, skulls and birth canals, then so be it.


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