When and why did masturbation evolve in primates? A new study provides clues
Though masturbation is common across the animal kingdom, it seems, at its face, to be an evolutionary paradox: Why would an animal waste time, energy and reproductive resources on self-pleasure instead of copulating with a partner? Studies on individual species have found some explanations. Low-ranking Japanese macaques (Macaca fuscata), for example, masturbate to keep their sperm fresh for when they get a rare chance to mate. But the questions of when and why masturbation evolved in the first place have remained unsolved. A new study, published in the June 7 Proceedings of the Royal Society B, suggests that the evolutionary history of masturbation in primates extends back at least 40 million years, and the behavior might indeed help male primates be ready to mate when they get the chance, and also stay free of disease. The authors are “the first to use a cross-species approach” to explore the function of masturbation, says Lateefah...