Tinder for orang-utans: comparing sexually selective cognition among Bornean orang-utans (Pongo pygmaeus) and humans (Homo sapiens)

Abstract

Cognitive processes play an important role in human mate choice. However, far less is known about this topic in non-human animals. In this thesis, I take a comparative approach to sexually selective cognition by studying humans (Homo sapiens) and Bornean orang-utans (Pongo pygmaeus). I start by reviewing the literature on sexually selective cognition. Hereafter, I show that visual, but not auditory or olfactory attractiveness, plays a major role in initial human mate choice. Furthermore, I show that attractiveness has a profound influence on visual attention in humans, and that attentional biases towards attractive conspecifics may be associated with mate choice. I explore the same topic in Bornean orang-utans by presenting them with stimuli of fully developed males or males experiencing arrested development. The results of these studies suggest that orang-utans preferentially attend to fully developed males, but only in the eye-tracking task and not in touchscreen tasks. The last chapter explores vocalisations, and suggests that orang-utan mate preferences might reflect in female vocal behaviour. Altogether, the results of this thesis suggest that humans and orang-utans show cognitive biases towards mate-relevant traits. However, better understanding of the link between such biases and actual mate choice remains of pivotal importance.