Homosexuality in primates

Homosexual interactions were documented in more than 50 primate species, including humans. Homosexual behaviour is defined as either genital contact, genital manipulation or combination of both between same-sex individuals. The aim of this thesis is to systematically summarize the past knowledge of homosexual behavior in primates and critically analyze its possible functions. Homosexual behaviour varies in frequency, context and form in which this behaviour occurs, both between species, between males and females and during ontogenesis. I summarise not only studies looking recording homosexual behaviour in different primate species, but also regarding its form and the circumstances under which such behaviour occurs. Furthermore, in this thesis I introduce several sociosexual functions explaining homosexual behaviour, which are described most frequently: 1) dominance assertion, 2) tension regulation, 3) reconciliation, 4) alliance formation and social-bonding and 5) training for heterosexual mating. Sexual/hedonic aspects of this behaviour also form significant part of homosexual interactions. Possible functions of homosexual behaviour do not clearly point to a single explanation, homosexual behaviour could be multifunctional similarly to humans. Keywords: homosexual behaviour, homosexuality,..