Are we hard-wired for infidelity?

Monogamy may be held up as an ideal, but evolution has other ideas

Most of us know people in committed relationships, even lifelong marriages. And we also know stories about relationship transgressions, of partnerships tested or broken by infidelity.

As an evolutionary biologist who studies sex and relationships, I'm fascinated by these two truths. We humans make romantic commitments to each other - and some also break those commitments by cheating.