Masturbation in the Animal Kingdom

ABSTRACT

Masturbation is one of the most common sexual behaviors in humans. It is also a phylogenetically widespread trait of various other mammalian and some non-mammalian species. Several hypotheses have been proposed aiming to explain the function of masturbation in primates and other species. These were mainly based on observations of nonhuman primates such as rhesus macaques or bonobos and rodents such as African ground squirrels. Based on these observations various scholars suggested that masturbation improves ejaculate quality, decreases the risk of contracting sexually transmitted infections or is merely a by-product of sexual arousal and thus an alternate outlet to copulation. While these theories may explain some facets of masturbation in some species, they do not explain why masturbation is so widespread and has developed in various species as well as our hominid ancestors. Moreover, the research on which these theories are based is scarce and heavily focused on male masturbation, while female masturbation remains largely unexplored. This sex difference may be responsible for the one-sided theorizing that attributes a specific biological benefit to masturbation. We propose that the widespread prevalence of masturbation in the animal kingdom may be better explained by viewing masturbation as a primarily self-reinforcing behavior that promotes pleasure both in human and in nonhuman species.

KEYWORDS:

• masturbation
• autosexual behavior
• genital stimulation
• animals
• pleasure

Acknowledgment

We thank Prof. Dr. V. Sommer from University College London for the stimulating exchange and for the insights into current research on masturbation in primatology.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Notes

1. This definition of sexual pleasure focuses on genital sensations to facilitate cognitively independent comparisons between species based on physiological conditions. However, it does not provide an absolute definition, as physiological sensation is not the only source of sexual pleasure (for example, see Ostrander, 2009; Tepper, 2000).