>>11705056Big breasts are a mainly visual stimulus, they attract can more partners and thereby increase the reproduction rate, but that isn't a must.
The round form is meant to mimic the buttocks because that is the original stimulus.
Humans have a higher tendency than most other animals to have sex in a front-to-front-position where the chest becomes more important than the buttocks.
Nevertheless, the rear is still a working stimulus, and the are many "butt-people", so even a woman with no breasts at all can attract and reproduce with the right partner.
Outcomes of this reproduction could inherent the tendency to focus on the rear and be indifferent towards the breast.
Another important factor is the circumstance, that the mere optic advantage of the breast can be a real disadvantage.
Women with very big breasts are more likely to suffocate their children during breastfeeding.
Big breast do not give more milk than small ones, as the glandular tissue is only located around the nipple.
The roundness of the breast can also be a more important stimulus than their mere size.
Big breasts lose their roundness fast and begin to sag, especially when not weraring a brassiere, which many people find unattractive.
Smaller ones retain their form much longer.
That being said, human clothing can be another important factor to humas enormous breast size compared to other animals. A small breast stays round while naked, but is much less noticable while wearing clothing.
A big breast is much more noticeable through clothing and also can retain its round form due to the support from the clothing.
Most populations where woman don't wear clothes tend to have smaller breasts, mainly indigenous tribes.
This is also true for other cultures before there was supportive clothing.
As many woman can't even run without a sport bra, it wouldn't be likely for a breast size above a C cup to be evolutionary favored if woman didn't wear clothes.
