I think the author of "The Naked Ape", (Desmond Morris?) set forth the breasts-as-substitute-buns thing as fact, but I've no idea if it was original with him. I suspect that there isn't really a grain of anything but conjecture there. I think he also informed the world of the "fact" that lipstick was invented to make lips look more like vaginal labia. I'm, uh, not totally convinced of that, either.