Via which gradual path should foreskin disappear? If I'm not mistaken, it's formed together with vital parts of the penis in embryo. Beneficial variations in foreskin would therefore be highly likely to cause detrimental changes in the other parts.
No, it's not. This is how we refine where variation exists and it does with foreskins. They're not like spines trying to cope with us standing up.
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Then explain why our foreskins would adapt to small advantages over the long run, whereas our spines are still ill-adapted to bipedal stance.
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Because variation in foreskin length exists enabling them to grow longer or shorter but no human had a spine suited to bepedalism so it had to adapt imperfectly.
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Have a look at the info I sent. We had foreskins way before we were human and they always served the same function. Changes in them to become longer & more complex are small but driven by something. Our spines did not serve the function they do now. We move completely differently
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I read it. The spine should then have a much greater impetus in changing than a foreskin that was functional as-is, right?
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Impetus? Evolution doesn't work by what it is most needed to do apropos of nothing. Variation needs to exist and certain traits be beneficial before it can make changes within a population.
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I have a duplex renal system and so does my mother. It caused both of us problems in pregnancy so we could only have one child. My daughter did not inherit it and so it has been naturally selected out. If it had been beneficial, we'd have had more children & passed it on.
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That isn't natural selection. That's just being lucky in not passing it on. If you hadn't been able to reproduce, it would have been NS'ed out.
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That is natural selection. It made us only able to have one child who had a 50% chance of inheriting it. If we'd been able to have more children, there would be more copies of it now. Instead, it came to an end with the first child who didn't inherit it.
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