Some time ago there was a hypothesis published,suggesting evolution made breasts mimic buttocks for either primitive men being attracted to women when they started to walk on two legs, or to discourage sexual intercourse from behind for other reasons I can’t remember. I can find many posts about this online, but I can’t find any reference to the original idea. Can anyone provide information about this?
Eventually, I found it, here it is:
In considering the human animal, zoologists proposed that the human female is the only primate that possesses permanent, full-form breasts when not pregnant. Other mammal females develop full breasts only when pregnant. The zoologist Desmond Morris proposed that the rounded shape of a woman's breasts evolved as frontal, secondary sex characteristic that is a sexual-attraction counterpart to the buttocks, and so encouraged frontal copulation, the reason being that while other primates mate by means of the rear-entry position, the upright, bipedal human being was likelier to successfully copulate face to face in the missionary position.