Two of my most favorite books tries to shine light on some of the different aspects of your (first) question. Maybe the unexpected findings during the pursuit of this question will be as fascinating to you as it was to me.

The Mating Mind: How Sexual Choice Shaped Human Nature (2000) (Geoffrey Miller)

The Red Queen: Sex and the Evolution of Human Nature (Matt Ridley)

https://en.wikipedia.org/wiki/The_Red_Queen:_Sex_and_the_Evo... https://en.wikipedia.org/wiki/Geoffrey_Miller_(psychologist)...