Why do men have nipples?
They serve no purpose.
Question: why do men have nipples? They serve no purpose.
Answer: Because females need nipples and generating a male body without nipples is biologically too complicated.
Welcome to Costs Matter, a series that asks different questions all of which have the same answer: to better manage costs. The costs are frequently economic though not always. The series focuses narrowly on the impact of costs. It does not claim these costs are the only reason things are as they are. To read more in the series, visit https://medium.com/galileo-onwards/costs/home.
Humans (and, for all I know, all sexually reproducing species) have a huge problem: the entire organism must develop from a single cell. Picture that for a moment. An adult human is made of at least 15 trillion cells. That’s 15,000,000,000,000 cells [ref, National Geographic]. How do you get to 15 trillion from one cell? That’s not all, the instructions for the organism’s development are contained within that single cell — i.e. the cell’s DNA.
This is a ridiculously complicated problem. The cells have to divide at the right time, by the right amount, form organs and so on. This is hardly a solved problem. Anyway, in light of such a complications, you can imagine there are shortcuts and/or the occasional bugs. This means there have to be large commonalities in male and female DNA. Males and females are mostly the same with specific differences in only specific locations. This is why males have nipples. The human development proceeds along the same path for both genders. Coding no nipples for males is more complicated than giving males useless nipples. Costs matter, you see.
The late great paleontologist and prolific science writer, Stephen Jay Gould, addressed this very topic in one of his 300 essays in the science magazine, Natural History. The following is what he wrote an essay provocatively titled, “Male Nipples and Clitoral Ripples”:
Both sexes are variants upon a single ground plan, elaborated in later embryology. Male mammals have nipples because females need them — and the embryonic pathway to their development builds precursors in all mammalian fetuses, enlarging the breasts later in females but leaving them small (and without evident function) in males.
The above essay is available in Gould’s 1991 book, “Bully for Brontosaurus”.
