Evolution of BAP

How did this visual BAP originate? Was there an era in evolutionary history when men and women walked around naked?
That must have been before humans started wearing clothing, or animal skins. Animal skins served primarily to prevent getting cold in chilly regions, for example in Europe. Perhaps, when the forerunners of modern humans still roamed Africa, people wore very little clothing, literally. At that time, physically attractive forms would have developed over generations to bring both sexes closer together. From a distance, a man could already recognize a young woman and begin to seek contact.
However, when humanity began covering itself with animal skins, and later with clothing, there was little direct sexual selection pressure on the emergence or preservation of this physical configuration. Yet this BAP has remained and has even become more beautiful over the centuries.
Such a BAP likely acquired a secondary role: intimacy (first phase) only arose when two people had fallen in love with each other. This was followed by nudity during committed courtship and reproduction (second phase). In the morning upon waking, the man could appreciate the full visual beauty of the woman. This could have a stabilizing effect on the romantic relationship.

 
Image: The light/dark nipple is the afterimage of the eye.

A Woman's Contour in Profile

Nose-bulb or Breast-nipple?
Another similarity in curves can be seen when a beautiful (naked) woman is viewed from the side:
The nose line of an upturned nose and the breast line from neck to breasts have a similar/proportional shape (curve).

The nose line ends in the round nose bulb.
The breast line ends in the round breast (with nipple).
In the neck (at the front), the curve in the neck is similar to the curve in the bridge of the nose (between the eyes).