@Francis,
And no wonder. They are not simple questions. I'm not even sure they are questions.
I don't see how it is possible to discuss our western mating patterns in terms of evolution science at all. Our whole system of thought is derived from a rejection of evolutionary principles and an attempt, which may well prove fruitless in the long run, to overcome them.
Various experts have attempted to untangle mating patterns in a number of cultures and found themselves in a maze. Even with the patterns in class groups and regional groups within one culture. The Australian aboriginal matrilineal system is a good example.
Concepts of beauty are also culturally determined. Emphasis on the head is extremely weak in many systems. It is a bar-room jest of some ancient lineage that one doesn't look at the mantlepiece when poking the fire.
The Venus I often mention is a good example. And the head in Manet's Olympia is the focus. As it is in the Giaconda although in that there is a combination effect which isn't immediately apparent to a casual observer. Even though I have seen the combination quite clearly and obviously twice I can still look at it and be unable to see it. But on the two occasions it was plain. And I only looked for it when an art critic pointed it out.
"Standing on the waters, casting your bread,
While the eyes of the idol in the iron head
Are glowing. " Jokerman Bob Dylan.
You could consult The Great Mother by Erich Neumann. That gives an idea of the range of beauty in the record of cultures deriving from the art they have left behind. A pile of skulls is an item of beauty in some places.
On Neumann's Jungian conception our emphasis on the head might be said to be "unusual". However successful.
The steatopygia, idealised by Hottentots, is considered ugly by most of us here. Not all of us though. And what about plate lips, neck stretch rings and crushed tiny feet.
Questions in this field only result in more questions.