Female mounting in Japanese macaques : proximate and ultimate perspectives on non-conceptive sex

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Ottenheimer Carrier, Lydia
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Lethbridge, Alta. : University of Lethbridge, Dept. of Psychology
Japanese macaques are unique in their sexual behaviour, adult females perform both female-female and female-male mounting. Female-male mounting is hypothesized to be adaptive, and female-female mounting is a functionless by-product of this adaptation. In this thesis, the proximate and ultimate forces behind both forms of mounting were explored using Eshkol-Wachman Movement Notation. In Chapter 2, the hypothesized adaptive value of female-male mounting was supported, as female-male mounts were related to greater subsequent male-female mounting. Additionally, the majority of female-male mounts were female-initiated, and males stood to be mounted in response to both ambiguous cues and explicit signals put out by females. In Chapter 3, the phylogenetic relatedness of female-male and female-female mounting was investigated by comparing the limb positions employed by mounters during both behaviours. Female-male and female-female mounters did not differ in the limb positions used during mounts, providing support for the hypothesized evolutionary link between the two.
female-female mounting , female-male mounting , Japanese macaques , limb positions , mounting behaviour