Hi mr .David Wynick
Do you really believe the male nipples are useful in male mammals or humans?!
because of your answer in this post:http://www.askabiologist.org.uk/answers/viewtopic.php?id=14441

I think you are perhaps misinterpreting David's post - he said they are functional when subjected to "female like" endocrine states (induced articficially or by disease).

Are they "useful" - well that depends on what you mean by useful! In an evolutionary sense there is little evidence that male nipples increase fitness (i.e. there would be little cost to losing them) but equally it's not apparent that they impose a cost (i.e. no selection against nipple presence in males) which is normally required for traits to become sex-limited in their expression (think e.g. peacocks tail that is a net benefit for males who need to attract a mate, but is also expensive to produce and increases predation risk - so is a net cost to females). The reason for this of course is that males and females have a shared genetic architecture - so there has to be "conflict" between the sexes to drive the evolution of mechanisms that result in only one sex having particular genes (which can happen through Y linkage in males), or mechanisms to repress gene expression in one sex but not the other (e.g. sensitivity of trait expression to ciruclating hormones in the case of some nipple function, but not presence/absence).

This idea is outlined more eloquently that I can do here:
http://www.scientificamerican.com/artic … e-nipples/

Last edited by Alistair Wilson (18th Feb 2016 11:45:54)