This reminds me of Stephen J Gould's explanation for why men have nipples: In utero the male and female fetus initially develop the same features, and only afte

This reminds me of Stephen J Gould's explanation for why men have nipples: In utero the male and female fetus initially develop the same features, and only after the nipples have been formed do males and females start to look different. Nipples aren't useful for men, but men have them because they are useful for women.