Geneticists have a better understanding of how prehistoric pairings unfolded, with new research suggesting they were mostly between male Neanderthals and female humans.

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.

For years, geneticists have wrestled with a curious absence: many modern people carry Neanderthal DNA, yet large stretches of the human X chromosome are almost empty of it. A new study argues that ...