Why do men have nipples when they’re not breastfeeding?
One of our readers asks us on the CleverlySmart Facebook page for the question of the week. Each week, we select a question from reader to which we provide an answer. Thank you very much for your curiosity. Why do men have nipples when they’re not breastfeeding?
The Y chromosome of men, responsible for the presence of nipples
If men have nipples, it’s simply because of the Y chromosome! Or rather its delay in setting up. This chromosome, responsible for the formation of the male sex organs and the production of male hormones such as testosterone, is only active after six to eight weeks. In the meantime, the X chromosome, at the origin of the formation of female sexual organs and the production of female hormones such as estrogen, alone controls the development of the embryo, and initiates the conception of breasts.
When the Y chromosome becomes functional in humans, it blocks the latter: at this stage, only the nipples have appeared. The latter do not have a lactation role in men… and yet, that does not mean that they cannot produce milk at all. Know that there is in Central Africa a population of 20,000 pygmies whose men spend a lot of time with newborns and some manage to get a lactation process. In 2005, The Guardian wondered: “Are these the ‘best dads in the world'”?
In Dyacopterus spadiceus bats, the male has functional teats
About ten years earlier, the Canadian zoologist Charles Francis and his team discovered in a forest of Kuala Lumpur in Malaysia, disconcerting bats, the dyacoptères (Dyacopterus spadiceus). Adult males have functional udders: they deliver milk when squeezed!
In a study published in Nature in 1994, the researchers explained that they obtained from the two males between 4 and 6 microlitres, which is very little compared to a female of the same species which can supply 350 microlitres from a single udder… But this can always help out if the female bat is absent, to find food for example.