Crazy question I know. I was wondering why many mammals can voluntarily expel their placenta, but humans can’t. One example is deer do this when they are in danger and need to skedaddle. Why can’t we do that?
In: Biology
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Humans do this as well. It is not voluntary but neither is it for deer. If a pregnant women is subjected to trauma or stress they can abort their fetus. It is a very similar mechanism as with deer. What is different about deer is that because they are such a big pray animal they have evolved to get easily stressed. So you can scare a deer enough to stress it to force an abortion. But it takes a lot more to stress a human that much.
We wouldn’t be able to skedaddle anyway because of the anatomy of the vagina and pelvis due to our adaptations for bipedalism; birth is typically a much longer and arduous process for humans compared to other animals, so we wouldn’t have much of an evolutionary advantage for it.
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