Humans don’t have a defined mating season like deer or wolves. Here’s how evolution blended biology, culture and social life into year-round intimacy.

When ancient humans mated, dad was a Neanderthal, mom was Homo sapiens.

Many of us think of our own species as a monogamous one. We select a mate, and we stick with them, or so we tend to believe. But are modern humans really as monogamous as we assume, and are we any ...