The Evolution of Men's and Women's Desires

The four universal conflicts that undermine men’s and women’s relationships.

• Human sexual psychology evolved to cope with ancestral adaptive problems over millions of years.

• Males and females face different evolutionary challenges that impact their love lives.

• Conflicts between the sexes tie to different evolutionary-based desires of males and females.

Biologists have a very simple and useful definition of what is male and what is female, whether we are fish, ferns, or human beings. An individual can either make many small gametes (sex cells) or fewer but larger gametes. The individuals that produce smaller gametes are called "males," and those that produce larger ones are called "females."
“The cellular imbalance is at the center of maleness,” says Steve Jones, a professor of genetics and head of the prestigious Galton Laboratory at the University College of London. “It confers on males a simpler sex life than their partners, together with a host of incidental idiosyncrasies, from more suicide, cancer, and billionaires to rather less hair on the top of the head.” 
The Evolution of Men's and Women's Desires