Abstract
Abstract Same-sex sexual behaviour has been documented across the animal kingdom, and is thought to reflect and enhance dyadic cooperation and tolerance. For instance, same-sex fellatio — the reception of a partner’s penis into another’s mouth — has been reported in several mammalian species other than humans. Although same-sex sexual behaviour is observed in our close relatives, the chimpanzees, fellatio appears to be very rare — as yet there are no published reports clearly documenting its occurrence. At Chimfunshi Wildlife Orphanage in Zambia, we observed an instance of fellatio occurring during a post-conflict period between two adult male chimpanzees (born and mother-reared at the sanctuary) where one of the males was the victim. We discuss this event with respect to the putative functions of homosexual behaviour in great apes. Given its rarity in chimpanzees, this fellatio between adult males also highlights the apparent behavioural flexibility present in our close relatives.
Highlights
Same-sex sexual behaviours can occur in a range of contexts in animal taxa, in both chimpanzees and bonobos, these behaviours are especially common during socially tense periods including pre-feeding, post-conflict periods, inter-group encounters, and, for chimpanzees, before boundary patrols (Paoli et al, 2007; Wilson et al, 2007; Herbinger et al, 2009; Clay & de Waal, 2015; Wittig et al, 2016; Samuni et al, 2019, see supplementary material)
We described an instance of same-sex fellatio occurring between two sanctuary-living adult male chimpanzees
Fellatio has been observed in other mammals (Ogawa, 2006; Tan et al, 2009; Sergiel et al, 2014; Sugita, 2016), including captive/semi-captive bonobos and chimpanzees (Heesen, personal communication) it has not yet been reported among adult chimpanzees during social tension, with two previous reports noting the occurrence of oralgenital contact among play in immature chimpanzees (Savage & Malick, 1977; Savage-Rumbaugh & Wilkerson, 1978)
Summary
Same-sex sexual interactions, i.e., genital contacts, mounting or other sexual solicitations between same-sex partners have been documented in many animal taxa including mammals, birds, marine life, and insects Same-sex sexual behaviours can occur in a range of contexts in animal taxa, in both chimpanzees and bonobos, these behaviours are especially common during socially tense periods including pre-feeding, post-conflict periods, inter-group encounters, and, for chimpanzees, before boundary patrols (Paoli et al, 2007; Wilson et al, 2007; Herbinger et al, 2009; Clay & de Waal, 2015; Wittig et al, 2016; Samuni et al, 2019, see supplementary material). By reporting on the occurrence of fellatio among adult male chimpanzees during a socially-tense period, we believe our observation can contribute to a richer understanding of the form and function of same-sex sexual behaviours in primates
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