Research has unveiled that masturbation, predominantly in males, has a long-standing evolutionary trajectory in primates and serves vital functions in augmenting reproductive success and mitigating the risk of sexually transmitted infections (STIs). Information compiled from diverse sources indicates that this practice is common among captive and wild primates of both genders. It could have existed in the shared ancestor of all monkeys and apes, but further examination is needed to understand its implications in females.
Masturbation is pervasive throughout the animal kingdom, with primates, including humans, showing significant occurrences. Historically, it was considered either a symptom of a disease or a consequence of sexual excitement. Existing studies lacked the coherence to fully illustrate its distribution, evolutionary roots, or adaptive significance. However, a recent study published in the Proceedings of The Royal Society B posits that this behavior could offer evolutionary advantages.
The research findings suggest that masturbation is an age-old characteristic in primates. In males, it is shown to enhance reproductive outcomes and aids in avoiding STIs.
Led by Dr. Matilda Brindle from UCL Anthropology, the team amassed the most comprehensive dataset on primate masturbation by consolidating information from nearly 400 sources, including academic papers and direct inputs from primatologists and zookeepers. This large collection of data enabled the researchers to chart the distribution of autosexual behavior across primates and gain insights into its evolutionary origins in both genders.
The study concludes that masturbation has an extended evolutionary past among primates and was probably a trait of the common ancestor of all monkeys and apes, including humans. The masturbation habits of other primates, such as lemurs, lorises, and tarsiers, remain uncertain due to limited data.
Dr. Brindle and her team explored several hypotheses to decode why evolution would favor this ostensibly non-functional trait.
The “postcopulatory selection hypothesis” suggests that masturbation aids successful fertilization. It increases arousal before intercourse, and by shedding low-quality semen through masturbation, it makes way for fresh, high-quality sperm, thereby increasing the chances of successful procreation. The study found evidence in support of this hypothesis, demonstrating that male masturbation has evolved along with multi-male mating systems where male competition is intense.
Another theory, the “pathogen avoidance hypothesis,” proposes that male masturbation reduces the risk of contracting an STI after copulation by cleansing the urethra with ejaculate obtained through masturbation. The research team found corroborating evidence for this hypothesis, showing that male masturbation has co-evolved with high STI loads across primate species.
The role of female masturbation, however, remains less understood due to limited reports, which hamper statistical analysis. The researchers call for more data on female sexual behavior to comprehend the evolutionary purpose of female masturbation better.
Dr. Brindle, the lead researcher, commented, “Our findings offer valuable insights into a widespread, but inadequately understood, sexual behavior and mark a considerable leap in our comprehension of the functions of masturbation. The fact that autosexual behavior may have an adaptive function, is widespread throughout the primate order, and is observed in both captive and wild-living members of both sexes, highlights that masturbation is a part of a range of healthy sexual behaviors.”
The study was supported by the Natural Environment Research Council and involved researchers from UCL Anthropology, the UCL Centre for Biodiversity & Environment Research, and Queen Mary University of London.
Source: “The evolution of masturbation is associated with postcopulatory selection and pathogen avoidance in primates” by Matilda Brindle, Henry Ferguson-Gow, Joseph Williamson, Ruth Thomsen, and Volker Sommer, 7 June 2023, Proceedings of the Royal Society B Biological Sciences. DOI: 10.1098/rspb.2023.0061
This site uses Google Analytics and associated cookies across the TrendMD network (widget, website, blog). Learn more by clicking here. Accept Decline
Table of Contents
Frequently Asked Questions (FAQs) about Evolutionary History of Masturbation
What does the new study on masturbation reveal?
The study reveals that masturbation, especially in males, has a long evolutionary history among primates and plays a crucial role in increasing reproductive success and reducing the risk of sexually transmitted infections (STIs). This behavior is prevalent in both captive and wild-living primates of both sexes.
Who led the study on the evolutionary history of masturbation?
The study was led by Dr. Matilda Brindle from UCL Anthropology.
What are the hypotheses tested in this study on masturbation?
The study tested two hypotheses. The “postcopulatory selection hypothesis” proposes that masturbation aids successful fertilization by increasing arousal and providing fresh, high-quality sperm. The “pathogen avoidance hypothesis” suggests that male masturbation can reduce the chance of contracting an STI after copulation by cleansing the urethra.
Why is the significance of female masturbation less clear?
The significance of female masturbation remains less clear due to fewer reports describing it, which reduces the statistical power of analysis. The team argues that more data on female sexual behavior are needed to better understand the evolutionary role of female masturbation.
What are the key conclusions of this study?
The study concludes that masturbation has a long evolutionary history among primates and was most likely present in the common ancestor of all monkeys and apes. It also finds that male masturbation enhances reproductive success and aids in avoiding STIs, supporting both the “postcopulatory selection hypothesis” and the “pathogen avoidance hypothesis.” The role of female masturbation requires further research.
More about Evolutionary History of Masturbation
- Proceedings of the Royal Society B
- UCL Anthropology
- Natural Environment Research Council
- UCL Centre for Biodiversity & Environment Research
- Queen Mary University of London
4 comments
important to understand that masturbation is not bad or unhealthy, but a normal part of sexual behavior. this study really puts things into perspective…
its just so fascinating how much we can learn about ourselves just by studying other primates. really cool study!
kinda makes sense when u think about it. everything we do has some kinda evolutionary basis, why not this?
interesting, but what about female masturbation? Wish they had more data on that too. equality in research people!!