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.
This might sound like a modern problem, but for me, it raises questions stretching far back in evolutionary time. Why did we evolve both a tendency to stay and a tendency to stray? If some among us will inevitably cheat, does that mean humans are hardwired for infidelity?
Answering those questions requires us to understand two key urges that propel our romantic and sexual behaviours as a species: the drive for a romantic bond and the drive for sexual novelty. Research shows that humans have evolved to seek secure partnership in the form of close pair-bond relationships, but it also shows, just as compellingly, that we’ve evolved a separate appetite for variety. Both drives are alive in us modern human beings, despite being at cross-purposes.
