When I give talks about the relevance of evolution to modern life, I can count on one regular question interrupting an orderly transition from lecture theatre to bar. Sometimes it comes with a “bet-you-didn’t-think-of-that-one” sneer. Far more often it is asked earnestly and with palpable empathy. The Question?

How do you explain homosexuality?

The very real fact that a large proportion of people across the world are sexually attracted to members of the same biological sex provides a giant obstacle to a Darwinian view of life.

And I am always happy to field this question because it allows me to explore, with the audience, some of the layered complexity of evolution. But a simple, definitive answer remains, for now, beyond reach. That may start to change, however, with a paper published today in The Quarterly Review of Biology.

Read more at The Conversation.