Men are fertile much later into their lives than women are.  That means there have always been more fertile men in the world than fertile women.   That means there has always been competition among men for fertile women.  That gives women choices of which men to have children with.  But that also means men have put a lot of thought over the millennia  into how to compete for women.   Our reproductive instincts have evolved to this mathematical relationship between fertile men and fertile women.  Talking to each other about our feelings about relationships gets a lot easier when…