|Must have dropped off in the wash|
As I glance down at my naked, pert and perfectly honed torso I am bleakly reminded of vestiginous (not a real word and not to be confused with vertiginous which is a real word. Please excuse the digression) things and the power of redundancy in the human body. I have been blessed/cursed with a supernumerary nipple. A perfect nipple in every anatomical degree except it is additional and placed in my midriff . Now if you think two nipples on a man are a waste, then three nipples is just wanton extravagance. And what tone of nipple rouge matches my complexion? Not as bizarre as it sounds. Some form of nipple grease is essential when I'm out running otherwise my nipples chafe something awful on my running top. There is nothing worse than sore bleeding nipples and as I have three the pain is multiplied accordingly. Although tis true that pain and pleasure are closely related; ecstasy or agony? Only you can be the judge.
So why do men have nipples? Evolution is supposed to sort out this type of thing, isn't it? A biological scalpel which ruthlessly 'cuts' out the unnecessary and useless leaving a well designed and perfectly adapted organism. Well that's the popular view, anyway.
So it is all down to a universal template. Anatomically speaking men and women are not all that different especially during the early embryonic stage of development. Until about 6 weeks into development male and female embryos are virtually indistinguishable. At 6 weeks into the pregnancy the SRY gene, on the Y chromosome, kicks in causing the differentiation of testes in the male embryo. The testes in their turn produce the hormone testosterone which unleashes a cascade of developmental changes culminating in the production of male genitalia. The default setting is always female and without testosterone the embryo will automatically become female. There is a condition called testicular feminisation where the foetus is chromosomally and genetically male, but because the primordial genitals are insensitive to testosterone they develop along the female pathway. Although technically 'male' these individuals are outwardly female in external appearance and psychosexual behaviour.
So it seems that males have nipples because females do. Clearly there are obvious advantages for females to have nipples. Males simply come along for the ride. While the presence of nipples in males confers no evolutionary advantage it has no detrimental effects either. And thus there is no selective pressure to alter the male developmental plan, male nipples in the evolutionary sense, are here to stay.
By the way, the acquisition of an extra nipple is a medical condition called polythelia. Nuff said