Why Do Women Have Breasts?

Well, without them, we would have to have some other kind of dripping milk gland hanging off our bodies.

Well the real reason is so the can nurse a baby when it is born from birth-1 and it is possible for a man to breast feed but it can be very difficult.

The simple answer might seem to be 'for feeding babies', but men can breastfeed, too (not easy, but they can) and few other mammals animals have large fat deposits around their teats (that's what breasts mostly are, lumps of fat).

So the fact that women have such pronounced mammary glands has puzzled evolutionary biologists. One theory is that it helps the baby feed because of how flat-faced newborns are; humans, especially our babies, have quite recessed jawbones compared to other primates. Desmond Morris speculated that large breasts resemble buttocks, and human males needed that visual sexual stimulus in order to figure out how to mate. It's also possible that women with pronounced mammary glands were the most appealing to males because they reminded a man of his own mother once swollen with milk. A woman with big mammaries would be comforting like mum but sexually available, too. Breasts can also serve to accentuate the small waist to large hip ratio that women usually have. So they serve to make women curvier. Being curvy is a genuine sign of fertility, so human males that preferred it would have been the ones to successfully pass on their preferences to offspring.

Breasts are handy as a fat reserve when the baby is born. Humans tend to concentrate fat reserves in certain areas of our bodies (like the bum), which may link to the hot climates we are thought to have evolved in (lots of fat reserves over the whole body would make us too hot in a hot climate). Very new mothers in a foraging or hunter-gatherer society wouldn't be able to go look for food, so might need to rely on their fat reserves until they had adequately recovered from the birth and could forage for themselves adequately again.