Women have breasts. Men (with exceptions like Meatloaf) do not. Selfish Gene Theory suggests a reason.
Evolution favors the fittest - the attributes of almost all organisms are present because those attributes give that organism some survival advantage.
Human females sport seemingly large lumps of redundant fatty tissue which must be a significant survival disadvantage in many cases. Suckling their young can only be part of the story, since almost all other mammals simply grow breasts toward the end of pregnancy, and can successfully feed whole litters of offspring with temporaries. It seems highly unlikely that nature could not have designed humans similarly. Useful storage of fatty reserves is unlikely. Other animals (including male humans) distribute excess fat more evenly as to not upset the balance of the creature. Women tend to wear bras during sport for good reason. Why then has nature given women breasts?
A clue may lie in the peacock's feathers. In this case a preference has been established for males with large and colorful tails. The females are simply more likely to choose mates with this generous plumage. In effect the males have tails because the females of the species prefer them. Once the trend is established, the females prefer the characteristic because they will have sons with that characteristic, which will in turn be successful because other females will prefer them and so on. So too, it seems, that breasts have evolved because men prefer women with breasts.
This strongly suggests that part of the design of the female body is for the attraction to men. Feminists may yell "misogynist! misogynist!", and believe that they can reverse five hundred thousand years of evolution, but would just be supporting the chauvinist view that logic wasn't an essential feature their design either. If in doubt they can lie back and enjoy it. Think of Darwin.
Then again the chauvinists might like to consider the design of the human penis.
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