Scientists have two theories as to why masturbation evolved in male primates. For women, the issue is more complicated.
From a historical point of view, masturbation This is thought to be pathological, or simply the result of sexual desire, and is especially common in primates, including humans. They have been considered unimportant, or taboo, and therefore do not exist without sufficient documentation to understand their history and evolutionary implications.
However, new research results have been published. Proceedings of the Royal Society B They conclude that this practice appears to have an evolutionary purpose in primates dating back tens of millions of years.
The results of this study show that masturbation is an ancient trait of primates that: It increases reproductive success and helps prevent sexually transmitted infections (STIs), at least in men.
For this study, anthropologists at University College London used approximately 400 sources, including 246 published scientific articles, 150 questionnaires, and personal correspondence from primatologists and zookeepers. to build the largest ever data set on masturbation in primates. From these data, the authors traced the distribution of narcissistic behavior in primates and understood when and why narcissistic behavior evolved in both females and males.
The researchers found that masturbation has an evolutionary history of tens of millions of years among primates and likely existed in the common ancestor of all monkeys and apes (including humans). It is less clear whether the ancestors of other primates (lemurs, lorises, tarsiers) masturbated, largely because data on these groups were sparse.
To understand why evolution produces this seemingly nonfunctional trait, Brindle and his colleagues tested several hypotheses.
of “Post-mating selection hypothesis” They suggest that masturbation helps with successful fertilization. This can be achieved in several ways. First, masturbation (without ejaculation) can increase arousal before sex. This is a particularly useful tactic for low-ranking males who are more likely to be interrupted during mating, helping them ejaculate sooner. Second, masturbation (with ejaculation) allows males to expel low-quality semen, leaving fresh, high-quality sperm available for mating, superior to that of other males. more likely. The researchers found support for this hypothesis, showing that male masturbation evolved with a multi-male mating system with intense competition between males.
of “Pathogen Evasion Hypothesis” Male masturbation has been proposed to reduce the chances of contracting a sexually transmitted disease after intercourse because it cleanses the urethra (the main site of infection for many sexually transmitted infections) with the ejaculate produced by masturbation. The research team also found evidence to support this hypothesis, showing that male masturbation co-evolved with high STD burden in the primate tree of life.
The meaning of female masturbation is not yet clear. This is common, but there are few reports explaining it, and the statistics are less analytic.
The researchers argue that more data on female sexual behavior are needed to better understand the evolutionary role of female masturbation.
In the words of anthropologist Dr. Matilda Brindle, “Our findings help shed light on a very common but poorly understood sexual behavior and represent a major advance in our understanding of the function of masturbation. It is shown that.”
“The fact that self-sexual behavior may have an adaptive function is ubiquitous across the entire class of primates, and is practiced by both males and females in captivity and in the wild, suggesting that masturbation is a healthy It shows that it is part of the repertoire of sexual behavior.”