Evolutionarily speaking, it is to attract potential mates. A large buttocks indicates fertility and that the female will be able to carry and bear young. This is why women developed wider hips and larger buttocks than men.

The buttocks are medial to the wrist. The wrist is lateral to the buttocks.

Buttocks

The buttocks can wiggle and jiggle when a person dances. The buttocks do not dance--they don't have that ability.

The sounds of my buttocks and slipknot in my buttocks in my buttocks in my buttocks so its like 10 arses and anal beads