Let's touch on a lighter, yet no less puzzling subject tonight:

Why in the world do men have nipples? What purpose do they serve (or did they serve)? And why hasn't evolution taken them away?

I found my answers, and was satisfied with them, here:

BBC Health - Dr Trisha Macnair responds to the question, "Why do men have nipples?"

It's a good article. If you don't have time to read it, here are some interesting bits from Dr. Macnair:

Men not only have nipples but rudimentary breast tissue too.

Men can even make breast milk if their nipples are stimulated enough - I once saw a case of a man whose wife enjoyed nibbling his nipples during sex - to the point where the hormonal control system which produces milk was switched on. He eventually needed medication to turn it all off again.

-But why?-

After conception the developing embryo follows a female template. It is only after 6-8 weeks that the effect of a gene on the Y chromosome kicks in for boy embryos. This gene stimulates the production and influence of hormones such as testosterone which 'masculinise' the embryo by altering physical development to form male features.

But nipples are formed very early in the embryo, before this masculinisation process takes place, and nothing that goes on later in fetal development reverses nipple formation.

-Evolution may hold an answer-

But why hasn't evolution meant that men have lost these nipples? Over the millennia the human body has been adapted and shaped by what makes one man more successful than another.

Having breasts and nipples - being able to suckle the young - may have conferred an advantage over those men who could not. For example it may have increased the chance of survival in lean times if the father could feed the babies as well as the mother. Conversely it doesn't seem to have been a disadvantage - nipple disease in men is very rare. Because nipples in men don't cause problems there is no genetic drive to lose them.

I just wanted to share that because it's something I've wondered for years but simply hadn't researched until now.

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I'm a thinker, not a talker - I've no-one to talk to, anyway --David Bowie, Space Oddity "Conversation Piece" (1969)