Even in the animal kingdom, males can have nipples. Male dogs have between eight and ten nipples on their undersides, male donkeys have rudimentary ones on the sides of their sheaths, even most whalebone whales have nipples. But why?
If the main function of a nipple is to allow milk to flow from inside the body to outside, why hasn't evolution seen them off males?
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In the case of most male mammals, nipples are seen as vestigial. This means that they are a body part that is small or not fully developped and doesn’t have a function.
Why do males have nipples?
Evolution fashions bodies that are exquisitely adapted to their environment. It’s not perfect, though. Why, for instance, do male mammals have nipples when only females need them?
Males and females develop along very similar lines using much the same genetic recipe. Characteristics of one sex will, then, be expressed in the other as long as they don’t confer a disadvantage. Male nipples neither help nor hinder.
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