Finally, science asks something important:
Many people may suppose that the question of the title is a stupid one, given that the answer is so obvious: women have breasts for feeding babies. In fact, the question is a good one, because it is a mystery why the vast majority of women has breasts. Most women are, at this moment, not lactating, and yet they have breasts. If breasts were merely for feeding babies, then most women would not have them. They would develop them only during pregnancy, and would lose them again when they stopped breast-feeding. Humans are unique in the animal world, in that they develop breasts at puberty and retain them into old age, whether or not they ever get pregnant. This requires an explanation.
It’s a long article offering many possible reasons and is difficult to sum up. Let me just say that whatever the reason… yay for boobies!