The male masturbation behavior in primates has been found to have evolved as a means of aiding reproduction and protecting against sexually transmitted infections. Masturbation is a common behavior among animals, particularly primates. However, the scientific community has been divided on whether it is a byproduct of sexual arousal or a pathological activity due to conflicting studies. To address this, researchers from the University College London conducted a comprehensive meta-study on primate masturbation, using data from 150 questionnaires, reports from primatologists and animal caretakers, and 246 studies. Their findings, published in Proceedings of the Royal Society B Biological Sciences, revealed that masturbation has a long evolutionary history in primates and was likely present in the common ancestor of all apes, great apes, and humans.
To understand why this seemingly non-functional trait evolved, the researchers examined several hypotheses. The post-copulation selection hypothesis suggests that male masturbation evolved alongside multi-male mating systems, where there is strong competition between males. The pathogen avoidance hypothesis also has evolutionary advantages, as male masturbation co-evolved with high STI rates in the primate lineage. The team’s findings shed light on a common but poorly understood sexual behavior and represent a significant step forward in our understanding of the functions of masturbation.
While the importance of male masturbation is clear, the role of female masturbation remains less understood. Although it is common, there are fewer reports describing it, which reduces the analytical power of statistics. The team argues that more data on female sexual behavior is needed to better understand the evolutionary role of female masturbation. Overall, the study highlights the adaptive function of masturbation and its prevalence in both captive and wild primates of both sexes, suggesting that it is a part of a healthy repertoire of sexual behaviors.
