Book contents
- The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology
- The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology
- Copyright page
- Contents
- Contributors
- Preface
- Part I Controversies and Unresolved Issues
- 1 The Female Sexual Orientation Spectrum in Evolutionary Perspective
- 2 The Evolution of Female Same-Sex Attraction
- 3 Male Bisexuality
- 4 Female Bisexuality
- 5 Masturbation in Primates
- Part II Applications to Health, Law, and Pornography
- Part III Nonhuman Primate Sexual Behavior
- Index
- References
5 - Masturbation in Primates
from Part I - Controversies and Unresolved Issues
Published online by Cambridge University Press: 30 June 2022
Edited by
Book contents
- The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology
- The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology
- Copyright page
- Contents
- Contributors
- Preface
- Part I Controversies and Unresolved Issues
- 1 The Female Sexual Orientation Spectrum in Evolutionary Perspective
- 2 The Evolution of Female Same-Sex Attraction
- 3 Male Bisexuality
- 4 Female Bisexuality
- 5 Masturbation in Primates
- Part II Applications to Health, Law, and Pornography
- Part III Nonhuman Primate Sexual Behavior
- Index
- References
Summary
Many vertebrate animals engage in masturbation and it is also prevalent in primates. Given the gregarious nature of this order, this is perhaps surprising, since, by definition, it occurs to the exclusion of others. Our research maps the masturbatory landscape of the primate order, highlighting the distribution and diverse forms self-stimulation of the genitalia takes: from an infant vervet monkey grasping his own penis in his mouth, to female chimpanzees using water spigots to stimulate their clitorises. We also examine the causation of this behavior. While autosexual behavior can be a substitute for allosexual interactions, many acts of masturbation seem to serve functions, which fall broadly under two categories: avoidance of pathogen transmission and reduction of mate competition. In terms of implications for human public health, the finding that masturbation is ubiquitous throughout the primate order, practiced by wild-living members of both sexes and all age-groups is a strong counter-argument to voices who condemn human masturbation as "unnatural."
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- Chapter
- Information
- Publisher: Cambridge University PressPrint publication year: 2022
References
Arnold, C., Matthews, L. J., & Nunn, C. L. (2010). The 10kTrees website: A new online resource for primate phylogeny. Evolutionary Anthropology: Issues, News, and Reviews, 19(3), 114–118.CrossRefGoogle Scholar
Bagemihl, B. (1999). Biological exuberance: Animal homosexuality and natural diversity. New York: St. Martin’s Press.Google Scholar
Baker, R. R., & Bellis, M. A. (1993). Human sperm competition: Ejaculate adjustment by males and the function of masturbation. Animal Behaviour, 46, 861–885.CrossRefGoogle Scholar
Bateson, P., & Laland, K. N. (2013). Tinbergen’s four questions: An appreciation and an update. Trends in Ecology and Evolution, 28(12), 712–718.Google Scholar
Baumeister, R. F. (2000). Gender differences in erotic plasticity: The female sex drive as socially flexible and responsive. Psychological Bulletin, 126(3), 347.Google Scholar
Bertossa, R. C. (2011). Morphology and behaviour: Functional links in development and evolution. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 366(1574), 2056–2068.CrossRefGoogle ScholarPubMed
Bielert, C., & van der Walt, L. A. (1982). Male chacma baboon (Papio ursinus) sexual arousal: Mediation by visual cues from female conspecifics. Psychoneuroendocrinology, 7, 31–48.Google Scholar
Brindle, M. (2018). Postcopulatory selection. In Vonk, J. & Shackelford, T. (Eds.), Encyclopedia of animal cognition and behavior (pp. 1–4). Cham: Springer International Publishing.Google Scholar
Brindle, M., Ferguson-Gow, H., Williamson, J., Thomsen, R., Cowlishaw, G., & Sommer, V. (in prep a). Primate masturbation: a comparative phylogenetic analysis.Google Scholar
Brindle, M., & Opie, C. (2016). Postcopulatory sexual selection influences baculum evolution in primates and carnivores. Proceedings of the Royal Society of London B: Biological Sciences, 283(1844), 20161736.Google Scholar
Brindle, M., Thomsen, R., & Sommer, V. (in prep b). An overview of primate masturbation: when, how, and why.Google Scholar
Bryson, K., Soligo, C., & Sommer, V. (2018). Ambiguity tolerance toward nonbinary sexuality concepts: Evidence from British newspapers. Journal of Bisexuality, 18(4), 446–477.Google Scholar
Bryson, K., Soligo, C., & Sommer, V. (2020). Interrogating boundaries against animals and machines: Human speciesism in British newspapers. Journal of Posthuman Studies, 4(2), 129–165.Google Scholar
Burton, F. D. (1972). The integration of biology and behavior in the socialisation of Macaca sylvana [sic] of Gibraltar. In Poirier, F. (Ed.), Primate socialization (pp. 29–62). New York: Random House.Google Scholar
Carpenter, C. R. (1942). Sexual behavior of free ranging rhesus monkeys (Macaca mulatta). I. Specimens, procedures and behavioral characteristics of estrus. Journal of Comparative Psychology, 33(1), 113.CrossRefGoogle Scholar
Curtis, R. F., Ballantine, J. A., Keverne, E. B., Bonsall, R. W., & Michael, R. P. (1971). Identification of primate sexual pheromones and the properties of synthetic attractants. Nature, 232, 396–398.CrossRefGoogle ScholarPubMed
Dittrich, L. (1968). Beobachtungen zur Masturbation bei Säugetieren im Zoologischen Garten. Zoologischer Anzeiger, 180, 299–312.Google Scholar
Dixson, A. F. (1977). Observations on the displays, menstrual cycles and sexual behaviour of the “black ape” of Celebes (Macaca nigra). Journal of Zoology, 182(1), 63–84.CrossRefGoogle Scholar
Dixson, A. F. (2009). Sexual selection and the origins of human mating systems. Oxford: Oxford University Press.CrossRefGoogle Scholar
Dixson, A. F. (2012). Primate sexuality: Comparative studies of the prosimians, monkeys, apes, and human beings, 2nd ed. Oxford: Oxford University Press.Google Scholar
Dixson, A. F., & Anderson, M. J. (2004). Sexual behavior, reproductive physiology and sperm competition in male mammals. Physiology and Behavior, 83(2), 361–371.CrossRefGoogle ScholarPubMed
Dobroruka, L. J. (1985). Abnormales Verhalten, Orgasmus und Trächtigkeitsdauer beim Vervet-Weibchen. Der Zoologische Garten N.F., 55, 341–342.Google Scholar
Dubuc, C., Coyne, S. P., & Maestripieri, D. (2013). Effect of mating activity and dominance rank on male masturbation among free-ranging male rhesus macaques. Ethology, 119(11), 1006–1013.CrossRefGoogle ScholarPubMed
Eberhard, W. G. (1996). Female control: Sexual selection by cryptic female choice. Princeton, NJ: Princeton University Press.Google Scholar
Erwin, J., & Mitchell, G. (1975). Initial heterosexual behavior of adolescent rhesus monkeys (Macaca mulatta). Archives of Sexual Behavior, 4, 97–104.CrossRefGoogle ScholarPubMed
Frearson, C. (2005). Masturbation in male primates: Taxonomic distribution, proximate causes and potential evolutionary functions. (Unpublished MSc thesis, Department of Anthropology, University College London).Google Scholar
Gerressu, M., Mercer, C. H., Graham, C. A., Wellings, K., & Johnson, A. M. (2008). Prevalence of masturbation and associated factors in a British national probability survey
. Archives of Sexual Behavior, 37(2), 266–278.CrossRefGoogle Scholar
Giles, G. G., Severi, G., English, D. R., McCredie, M. R. E., Borland, R., Boyle, P., & Hopper, J. L. (2003). Sexual factors and prostate cancer. BJU International, 92(3), 211–216.Google Scholar
Gunst, N., Vasey, P. L., & Leca, J. B. (2018). Deer mates: A quantitative study of heterospecific sexual behaviors performed by Japanese macaques toward sika deer. Archives of Sexual Behavior, 47(4), 847–856.CrossRefGoogle Scholar
Haake, P., Krueger, T. H. C., Goebel, M. U., Heberling, K. M., Hartmann, U., & Schedlowski, M. (2004). Effects of sexual arousal on lymphocyte subset circulation and cytokine production in man. Neuroimmunomodulation, 11(5), 293–298.CrossRefGoogle ScholarPubMed
Hamilton, G. V. (1914). A study of sexual tendencies in monkeys and baboons. Journal of Animal Behavior, 4(5), 295.CrossRefGoogle Scholar
Harlow, H. F. (1975). Lust, latency and love: Simian secrets of successful sex. Journal of Sex Research, 11(2), 79–90.CrossRefGoogle Scholar
Hart, B. L., Korinek, E., & Brennan, P. (1987). Postcopulatory genital grooming in male rats: Prevention of sexually transmitted infections. Physiology and Behavior, 41(4), 321–325.Google Scholar
Hawkes, K., Chisholm, J. S., Fairbanks, L. A., Johow, J., Kalcher-Sommersguter, E., Liebal, K., … & Finlay, B. L. (2017). Primate infancies: Causes and consequences of varying care. In Bard, K. & Keller, H. (Eds.), The cultural nature of attachment: Contextualizing relationships and development (pp. 69–108). Cambridge, MA: MIT Press.Google Scholar
Hazelwood, R. R., Dietz, P. E., & Burgess, A. W. (1983). Autoerotic fatalities. Lexington, MA: Lexington books.Google Scholar
Hess, J. P. (1973). Some observations on the sexual behavior of captive lowland gorillas, Gorilla g. gorilla (Savage and Wyman). In Michael, R. P. & Crook, J. H. (Eds.), Comparative ecology and behavior of primates (pp. 508–581). New York: Academic Press.Google Scholar
Hite, S. (1976). The Hite report: A nationwide study of female sexuality. New York: Seven Stories Press.Google Scholar
Hrdy, S. B. (1999). Mother Nature: Natural selection and the female of the species. London: Chatto and Windus.Google Scholar
Inoue, E. (2012). Male masturbation behaviour of Japanese macaques in the Arashiyama E troop. In Leca, J. B., Huffman, M. A., & Vasey, P. L. (Eds.), The monkeys of Stormy Mountain: 60 years of primatological research on the Japanese macaques of Arashiyama (pp. 204–220). Cambridge: Cambridge University Press.CrossRefGoogle Scholar
Jones, E. (2005). Masturbation in female primates: Taxonomic distribution, proximate causes and potential evolutionary functions. (Unpublished MSc thesis, Department of Anthropology, University College London).Google Scholar
Kanagawa, H., Hafez, E. S. E., Nawar, M. M., & Jaszczak, S. (1972). Patterns of sexual behavior and anatomy of copulatory organs in macaques. Ethology, 3, 449–460.Google Scholar
Kegel, A. H. (1948). Progressive resistance exercise in the functional restoration of the perineal muscles. American Journal of Obstetrics and Gynecology, 56 (2), 238–248.Google Scholar
Keverne, E. B. (1976). Sex attractants in primates
. Journal of the Society of Cosmetic Chemists, 27(6), 257–269.Google ScholarPubMed
Kinsey, A. C., Pomeroy, W. B., & Martin, C. E. (1948). Sexual behavior in the human male
. Philadelphia: W. B. Saunders Company.Google Scholar
Kinsey, A. C., Pomeroy, W. B., Martin, C. E., & Gebhard, P. H. (1953). Sexual behavior in the human female. Bloomington, IN: Indiana University Press.Google Scholar
Kollar, E. J., Beckwith, W. C., & Edgerton, R. B. (1968). Sexual behavior of the ARL colony chimpanzees. The Journal of Nervous and Mental Disease, 147(5), 444–459.Google Scholar
Komisaruk, B. R., & Whipple, B. (2011). Non-genital orgasms. Sexual and Relationship Therapy, 26(4), 356–372.Google Scholar
Laqueur, T. W. (2003). Solitary sex: A cultural history of masturbation. New York: Zone Books.Google Scholar
Leca, J.-B., Gunst, N., Ottenheimer Carrier, L., & Vasey, P. L. (2014). Inter-group variation in non-conceptive sexual activity in female Japanese macaques: Could it be cultural? Animal Behavior and Cognition, 1(3), 387–409.CrossRefGoogle Scholar
Leitzmann, M. F., Platz, E. A., Stampfer, M. J., Willett, W. C., & Giovannucci, E. (2004). Ejaculation frequency and subsequent risk of prostate cancer. Journal of the American Medical Association, 291(13), 1578–1586.Google Scholar
Levin, R. J. (2007). Sexual activity, health and well-being – the beneficial roles of coitus and masturbation. Sexual and Relationship Therapy, 22(1), 135–148.Google Scholar
Lieberman, H. (2017). Buzz: The stimulating history of the sex toy
. New York: Pegasus Books.Google Scholar
Lindburg, D. G. (1990). Proceptive calling by female lion‐tailed macaques. Zoo Biology, 9(6), 437–446.Google Scholar
Linnankoski, I., Hytönen, Y., Leinonen, L., & Hyvärinen, J. (1981). Determinants of sexual behavior of Macaca arctoides in a laboratory colony. Archives of Sexual Behavior, 10(2), 207–222.CrossRefGoogle Scholar
Lowenstein, L., Gruenwald, I., Gartman, I., & Vardi, Y. (2010). Can stronger pelvic muscle floor improve sexual function? International Urogynecology Journal, 21(5), 553–556.Google Scholar
Loy, J., Loy, K., Keifer, G., & Conway, C. (1984). The behavior of gonadectomized rhesus monkeys. In Szalay, F. S. (Ed.), Contributions to Primatology, 20, (pp. 1–144). Basel, Switzerland: Karger.Google Scholar
Masters, W. H., & Johnson, V. E. (1966). Human sexual response. London: J. & A. Churchill.Google Scholar
McBride, A. F., & Hebb, D. O. (1948). Behavior of the captive bottle-nose dolphin, Tursiops truncatus. Journal of Comparative and Physiological Psychology, 41(2), 111–123.Google Scholar
McDonnell, S. M., Henry, M., & Bristol, F. (1991). Spontaneous erection and masturbation in equids. Journal of Reproduction and Fertility (Suppl.), 44, 664–665.Google Scholar
Meston, C. M. (2000). The psychophysiological assessment of female sexual function. Journal of Sex Education and Therapy, 25(1), 6–16.Google Scholar
Minocher, R., & Sommer, V. (2016). Why do mothers harm their babies? Evolutionary Perspectives: Interdisciplinary Science Reviews, 41(4), 335–350.Google Scholar
Moretta, L., & Moretta, A. (2004). Unravelling natural killer cell function: Triggering and inhibitory human NK receptors. The EMBO Journal, 23(2), 255–259.Google Scholar
Nieuwenhuijsen, K., de Neef, K. J., & Slob, A. K. (1986). Sexual behaviour during ovarian cycles, pregnancy and lactation in group-living stumptail macaques (Macaca arctoides). Human Reproduction, 1(3), 159–169.CrossRefGoogle ScholarPubMed
Nieuwenhuijsen, K., de Neef, K. J., & Slob, A. K. (1987). Testosterone, testis size, seasonality, and behavior in group-living stumptail macaques (Macaca arctoides). Hormones and Behavior, 21(2), 153–169.Google Scholar
Nunn, C. L. (2003). Behavioural defences against sexually transmitted diseases in primates. Animal Behaviour, 66(1), 37–48.Google Scholar
Nunn, C. L., & Altizer, S. (2004). Sexual selection, behaviour and sexually transmitted diseases. In Kappeler, P. & van Schaik, C. (Eds.), Sexual selection in primates: New and comparative perspectives (pp. 117–130). Cambridge: Cambridge University Press.CrossRefGoogle Scholar
Nunn, C. L., Altizer, S. M., Sechrest, W., & Cunningham, A. A. (2005). Latitudinal gradients of parasite species richness in primates. Diversity and Distributions, 11(3), 249–256.CrossRefGoogle Scholar
Park, J. H. (2007). Distinguishing byproducts from non-adaptive effects of algorithmic adaptations. Evolutionary Psychology, 5(1), 47–51.Google Scholar
Parker, K. J., Buckmaster, C. L., Schatzberg, A. F., & Lyons, D. M. (2005). Intranasal oxytocin administration attenuates the ACTH stress response in monkeys
. Psychoneuroendocrinology, 30(9), 924–929.CrossRefGoogle ScholarPubMed
Patton, M. S. (1986). Twentieth-century attitudes toward masturbation. Journal of Religion and Health, 25(4), 291–302.CrossRefGoogle ScholarPubMed
Puts, D. A., & Dawood, K. (2006). The evolution of female orgasm: Adaptation or byproduct? Twin Research and Human Genetics, 9(3), 467–472.Google Scholar
Rahaman, H., & Parthasarathy, M. D. (1969). Studies on the social behaviour of bonnet monkeys. Primates, 10(2), 149–162.Google Scholar
Ransom, T. W. (1981). Beach troop of the Gombe. Lewisburg, PA: Bucknell University Press.Google Scholar
Ransom, T. W., & Rowell, T. E. (1972). Early social development of feral baboons. In Poirier, F. E. (Ed.), Primate socialization (pp. 105–144). New York: Random House.Google Scholar
Rider, J. R., Wilson, K. M., Sinnott, J. A., Kelly, R. S., Mucci, L. A., & Giovannucci, E. L. (2016). Ejaculation frequency and risk of prostate cancer: Updated results with an additional decade of follow-up. European Urology, 70(6), 974–982.Google Scholar
Rieger, G., Savin-Williams, R. C., Chivers, M. L., & Bailey, J. M. (2015). Sexual arousal and masculinity-femininity of women. Journal of Personality and Social Psychology, 111(2), 265–283.Google Scholar
Riesen, A. H. (1971). Nissen’s observations on the development of sexual behavior in captive-born, nursery-reared chimpanzees. The Chimpanzee, 4, 1–18.Google Scholar
Rosenblum, L. A., & Smiley, J. (1984). Therapeutic effects of an imposed foraging task in disturbed monkeys. Journal of Child Psychology and Psychiatry, 25(3), 485–497.Google Scholar
Rothe, H. (1975). Some aspects of sexuality and reproduction in groups of captive marmosets (Callithrix jacchus). Zeitschrift für Tierpsychologie, 37(3), 255–273.Google Scholar
Rowe, N., & Myers, M. (2017) All the world’s primates. Charlestown, RI: Pogonias Press.Google Scholar
Rowell, T. E., & Hartwell, K. M. (1978). The interaction of behaviour and reproductive cycles in patas monkeys. Behavioral Biology 24, 167, 141–167.Google Scholar
Russell, D. G. D., Sladen, W. J. L., & Ainley, D. G. (2012). Dr. George Murray Levick (1876–1956): Unpublished notes on the sexual habits of the Adélie penguin. Polar Record, 48(4), 387–393.Google Scholar
Sachs, B. D. (1995). Placing erection in context: the reflexogenic-psychogenic dichotomy reconsidered. Neuroscience & Biobehavioral Reviews, 19(2), 211–224.Google Scholar
Sarnoff, S., & Sarnoff, I. (1979). Sexual excitement and sexual peace: The place of masturbation in adult relationships. New York: Evans.Google Scholar
Schaller, G. E. (1963). The mountain gorilla: Ecology and behavior. Chicago: The University of Chicago Press.Google Scholar
Schurmann, C. (1982). Mating behaviour of wild orangutans. In de Boer, L. E. M. (Ed.), The orangutan: Its biology and conservation (pp. 268–284). The Hague: Dr. W. Junk.Google Scholar
Semple, S., Cowlishaw, G., & Bennett, P. M. (2002). Immune system evolution among anthropoid primates: Parasites, injuries and predators. Proceedings of the Royal Society B: Biological Sciences, 269(1495), 1031–1037.Google Scholar
Shadle, A. R. (1946). Copulation in the porcupine. The Journal of Wildlife Management, 10(2), 159–162.Google Scholar
Shumaker, R. W., Walkup, K. R., & Beck, B. B. (Eds.) (2011). Animal tool behavior: The use and manufacture of tools by animals
. Baltimore: JHU Press.Google Scholar
Sommer, V. (2000). The holy wars about infanticide. Which side are you on? And why? In van Schaik, C., & Janson, C. (Eds.), Infanticide by males and its implications (pp. 9–26). Cambridge: Cambridge University Press.Google Scholar
Sommer, V. (2006). Against nature?! An epilogue about animal sex and the moral dimension. In Sommer, V. & Vasey, P. (Eds.). Homosexual behaviour in animals. An evolutionary perspective (pp. 365–371), Cambridge: Cambridge University Press.Google Scholar
Sommer, V., Minocher, R., & Lowe, A. (2018). Infanticide. In Callan, H. (Ed.), The international encyclopedia of anthropology (12 volume set). Hoboken, NJ: John Wiley & Sons.Google Scholar
Sommer, V., Srivastava, A., & Borries, C. (1992). Cycles, sexuality, and conception in free-ranging female langurs (Presbytis entellus). American Journal of Primatology, 28, 1–27.Google Scholar
Sommer, V., & Vasey, P. L. (Eds.) (2006) Homosexual behaviour in animals. An evolutionary perspective. Cambridge: Cambridge University Press.Google Scholar
Starin, E. D. (2004). Masturbation observations in Temminck’s red colobus. Folia Primatologica, 75, 114–117.Google Scholar
Struhsaker, T. T. (1967). Behavior of vervet monkeys (Cercopithecus aethiops). University of California Publications in Zoology, 82, 1–64.Google Scholar
Suarez, S. S., & Pacey, A. A. (2006). Sperm transport in the female reproductive tract. Human Reproduction Update, 12(1), 23–37.Google Scholar
Tan, M., Jones, G., Zhu, G., Ye, J., Hong, T., Zhou, S., … & Zhang, L. (2009). Fellatio by fruit bats prolongs copulation time. PLOS ONE, 4(10), 1–5.Google Scholar
Thomsen, R. M. (2000). Sperm competition and the function of masturbation in Japanese macaques (Macaca fuscata)
. Ph.D. thesis, Munich: Fakultät für Biologie, Ludwig-Maximilians-Universität München.Google Scholar
Thomsen, R., & Soltis, J. (2004). Male masturbation in free-ranging Japanese macaques. International Journal of Primatology, 25(5), 1033–1041.Google Scholar
Thomsen, R., Soltis, J., Matsubara, M., Matsubayashi, K., Onuma, M., & Takenaka, O. (2006). How costly are ejaculates for Japanese macaques? Primates, 47(3), 272–274.Google Scholar
Thomsen, R., Soltis, J., & Teltscher, C. (2003). Sperm competition and the function of male masturbation in nonhuman primates. In Jones, C. B. (Ed.), Sexual selection and reproductive competition in primates: New perspectives and directions (pp. 436–453). Norman, OK: American Society of Prinatologists.Google Scholar
Thomsen, R., & Sommer, V. (2015). Masturbation (non-human primates). In Whelehan, P. & Bolin, A. (Eds.), The international encyclopedia of human sexuality ( Vol. 1 ) (pp. 754–755). Hoboken, NJ: John Wiley & Sons.Google Scholar
Thomsen, R., & Sommer, V. (2017). Masturbation. In Fuentes, A. et al. (Eds.), The International encyclopedia of primatology (pp. 773–774). Hoboken, NJ: John Wiley & Sons.Google Scholar
Tinson, A. H., Kuhad, K. S., Singh, K., & Al-Masri, J. (2000). Surgical technique to control sand masturbation in male racing camels. Journal of Camel Practice and Research, 7(2), 167–169.Google Scholar
Trivers, R. (1972). Parental investment and sexual selection. In Campbell, B. (Ed.), Sexual selection and the descent of man 1871–1971 (pp. 136–179). Chicago, IL: Aldine.Google Scholar
Trivers, R. L. (1985) Social evolution. Menlo Park, CA: Benjamin/Cummings Publishing Company.Google Scholar
van Hooff, J. A. R. A. M. (1967). The care and management of captive chimpanzees with special emphasis on the ecological aspects. Netherlands: Amsterdam University.CrossRefGoogle Scholar
van Lawick-Goodall, J. (1968). The behaviour of free-living chimpanzees in the Gombe Stream Reserve. Animal Behaviour Monographs, 1, 161–311.Google Scholar
Vasey, P., & Sommer, V. (2006). Homosexual behaviour in animals. Topics, hypotheses, and research trajectories. In Sommer, V. & Vasey, P. (Eds.), Homosexual behaviour in animals: An evolutionary perspective (pp. 3–42). Cambridge: Cambridge University Press.Google Scholar
Waterman, J. M. (1998). Mating tactics of male Cape ground squirrels, Xerus inauris: Consequences of year-round breeding. Animal Behaviour, 56, 459–466.Google Scholar
Waterman, J. M. (2010). The adaptive function of masturbation in a promiscuous African ground squirrel. PLOS ONE, 5(9), e13060.CrossRefGoogle Scholar
Waters, D. J., Sakr, W. A., Hayden, D. W., Lang, C. M., McKinney, L., Murphy, G. P., … & Tindall, D. J. (1998). Workgroup 4: Spontaneous prostate carcinoma in dogs and nonhuman primates. The Prostate, 36(1), 64–67.Google Scholar
Westergaard, G., & Fragaszy, D. (1987). Self-treatment of wounds by a capuchin monkey (Cebus apella). Human Evolution, 2(6), 557–562.Google Scholar
Whiten, A., Caldwell, C. A., & Mesoudi, A. (2016). Cultural diffusion in humans and other animals. Current Opinion in Psychology, 8, 15–21.Google Scholar
Wikelski, M., & Bäurle, S. (1996). Pre-copulatory ejaculation solves time constraints during copulations in marine iguanas. Proceedings of the Royal Society B: Biological Sciences, 263(1369), 439–444.Google Scholar
Wolfe, L. D. (1984). Japanese macaque female sexual behavior: A comparison of Arashiyama East and West. In Small, M. F. (Ed.), Female primates: Studies by women primatologists (pp. 141–157). New York: Alan R. Liss.Google Scholar
Zimmer, F., & Imhoff, R. (2020). Abstinence from masturbation and hypersexuality. Archives of Sexual Behavior, 49(4), 1333–1343.Google Scholar
Zukowsky, L. (1940). Zur Haltung und Pflege einiger Neuweltaffenarten. Der Zoologische Garten N.F., 12, 92–110.Google Scholar