[OldMan&TheWeed]

Being a tit man, I’ve wondered about this question for many years.

The most satisfactory explination I’ve found has come from reading The Naked Ape by Desmond Morris. In The Naked Ape Morris suggests that permanently enlarged breasts in human females resulted from hominid bipedalism. He argues that as early humans began walking upright, face-to-face encounters between the sexes became the norm, affecting the position used in sexual intercourse. Walking upright meant that males would no longer only mount females from behind as they do among non-human primates. In the non-human primate position, presentation of the female buttocks to the male is an erotic display that stimulates male interest and excitement. With the advent of bipedalism, Morris argues, if females were to be successful in shifting male interest around to the front, evolution would have to do something to make the female frontal region more stimulating to males. This was accomplished, Morris says, through self-mimicry in which female breasts came to look like rounded buttocks: female breasts became mimics of “the ancient genital display of [the] hemispherical buttocks.”

So it seems that human female breasts became sexual signals to attract males. Females with this trait would have increased mating opportunities, thereby passing the genes for permanently enlarged breasts on to subsequent generations.