For years, friendships between straight women and gay men have been a subject of pop culture fascination. Books, television shows, and feature length films have all highlighted this unique relationship, noted for its closeness and depth.

But with society’s attitudes toward gays and lesbians changing, it’s become all the more important to build a holistic understanding of the relationships between gay and straight people.

As a researcher in social psychology, I’ve often wondered: Why do straight female-gay male relationships work so well? Why are straight women so drawn to having gay men as friends? And when do these relationships typically form?

During the course of my research, I’ve discovered that the most interesting, compelling—and, arguably, most theoretically coherent—explanation is through the lens of evolution.

Specifically, I believe evolutionary psychology and human mating can help explain why relationships between straight women and gay men tend to flourish.