How did sex pop up? (Introduction)

by George Jelliss , Crewe, Wednesday, September 23, 2009, 12:58 (5539 days ago) @ David Turell

DT writes: "But I have a real point: how do two lines of organisms accommodate when they must? I've discussed mother and child with enlarging head (different DNA)."-I don't know why you find any difficulty with this. Obviously if there is a trend towards babies being born with larger brains and heads this will cause difficulties for the mothers who cannot cope with this, resulting in death of the mother or inability to bear further children. Mothers who can cope will survive and continue their line. On the other hand there is a limit to the size of babies heads, those that are too large will not survive the birth. So these evolutionary trends will be brought into balance by natural selection. I'm not a biologist so my explanation may be rather crudely expressed, but Darwinian evolution seems perfectly adequate to explain the case.-I've responded to your other comment in the Natures IQ thread.

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GPJ