Evolution of the primate breast was a later development in the sexual development of primates.
The early attraction in primates was to the buttocks which produced a rear mounting engagement. Over time the pre-human breast developed, switching the attraction from the buttocks to the breast leading to the front mount position. Now sexual development has gone to what we all know and do. Today some of those "primal attractions" are still present. Many males are attracted to the "buns"(primal) while many other males are attracted to the breast (modern). Maybe one could say that some males still harbor those old primal sex behaviors genes. Well with all that said, this is my "buns blog". Taking note that the image on the right ("spider bumps") could very well pass for "buns" or "boobs". Its your call. The one in the center IMO are a primal as you can get and what I would call the "a great set of buns", not knowing what we can't see (who cares) they would produce the the greatest sexual attraction in a "primal male". Take it for what it is worth, most of this is part of the evolutionary theory of sexual behavior in human development.