Primates also masturbate and this is why

Masturbation is not something exclusive to the human being, it is common in the animal kingdom and especially frequent among primates. A new study by British researchers suggests that this practice, at least in males, appears to serve an evolutionary purpose.

Historically, masturbation was viewed as pathological behavior or a byproduct of sexual arousal, and recorded observations were too fragmentary to understand its distribution, evolutionary history, or adaptive significance, says the study in the Proceedings of The Royal Society B.

The work points out that masturbation is an ancient trait in primates and that – at least in males – it increases reproductive success and helps prevent contracting sexually transmitted infections (STIs), according to a statement from University College London, which leads the study. study.

The team collected information from nearly 400 sources, including academic articles, questionnaires, and communications from primatologists and zookeepers, in order to trace the distribution of autosexual behavior among primates and understand when and why it evolved in both females and males.

To understand why evolution would produce this apparently nonfunctional trait, the team posed several hypotheses, the university says.

The “postcopulatory selection hypothesis” proposes that masturbation contributes to successful fertilization, which can be accomplished in a number of ways.

First, masturbation without ejaculation can increase arousal before intercourse and be an especially useful tactic for low-ranking males susceptible to interruption during copulation by helping them ejaculate more quickly.

On the other hand, masturbation with ejaculation allows males to get rid of lower-quality semen, leaving fresh, high-quality sperm available for mating, which is more likely to outperform that of other males.

The researchers corroborated these hypotheses by showing that male masturbation has coevolved with multiple mating systems in which competition between males is high.

Another hypothesis put forward by the team to understand the origin of masturbation is “pathogen avoidance”, which proposes that the male reduces the possibility of contracting an STI after intercourse, by cleaning the ejaculate from the urethra.

The team also found evidence in support of this hypothesis, showing that male masturbation co-evolved with a high STI burden in the primate tree of life, the statement added.

The importance of female masturbation remains less clear, because although it is frequent, there are fewer reports describing it, which diminishes the analytical power of the statistics.

The team argues that more data on female sexual behavior is needed to better understand the evolutionary role of female masturbation.

These results, according to the study's lead author, Matilda Brindle, “help shed light on very common but poorly understood sexual behavior and represent a significant advance in our understanding of the functions of masturbation.”

That autosexual behavior “can fulfill an adaptive function, is ubiquitous throughout the order of primates, and is practiced by members of both sexes in captivity and in the wild, demonstrates that masturbation is part of a healthy repertoire of sexual behaviors.”