We Like Big Butts and I'll Tell You Why

The human buttocks are a nexus of sexual attraction for men and women. Popular music, television, and movies all promote the buttocks as making both men and women attractive. In fact, this is so true that it has inspired the popular metonymy "piece of ass," referring to an attractive person, but why should this be true?

The human buttocks are a strange confluence of biological adaptation and coincidence. Adaptively, the human buttocks are a combination of muscle and fat dedicated to the primary human adaptation: walking. Early humans literally walked their way around the globe, so it is not surprising that we might judge the fitness of a potential mate based on their walking "equipment": calves, thighs, and, of course, buttocks.

Coincidentally, females of our nearest primate relatives, the chimpanzees, signal that they are going through heat with a swelling of the buttocks, so it seems likely that as human beings adapted to an upright stance, the increased muscle mass was read as a signal that a woman was sexually ready, driving the human transition from periods of "heat" to essentially continual reproductive receptiveness.

Because large asses are considered signs of sexual attractiveness, it is not at all surprising that buttock lifts would be less practiced than tummy tucks on the order of 1:50, while buttock augmentation would be a growing treatment for women and men.