title: Social Attention in the Two Species of Pan: Bonobos Make More Eye Contact than Chimpanzees.
abstract: Humans' two closest primate living relatives, bonobos and chimpanzees, differ behaviorally, cognitively, and emotionally in several ways despite their general similarities. While bonobos show more affiliative behaviors towards conspecifics, chimpanzees display more overt and severe aggression against conspecifics. From a cognitive standpoint, bonobos perform better in social coordination, gaze-following and food-related cooperation, while chimpanzees excel in tasks requiring extractive foraging skills. We hypothesized that attention and motivation play an important role in shaping the species differences in behavior, cognition, and emotion. Thus, we predicted that bonobos would pay more attention to the other individuals' face and eyes, as those are related to social affiliation and social coordination, while chimpanzees would pay more attention to the action target objects, as they are related to foraging. Using eye-tracking we examined the bonobos' and chimpanzees' spontaneous scanning of pictures that included eyes, mouth, face, genitals, and action target objects of conspecifics. Although bonobos and chimpanzees viewed those elements overall similarly, bonobos viewed the face and eyes longer than chimpanzees, whereas chimpanzees viewed the other elements, the mouth, action target objects and genitals, longer than bonobos. In a discriminant analysis, the individual variation in viewing patterns robustly predicted the species of individuals, thus clearly demonstrating species-specific viewing patterns. We suggest that such attentional and motivational differences between bonobos and chimpanzees could have partly contributed to shaping the species-specific behaviors, cognition, and emotion of these species, even in a relatively short period of evolutionary time.
authors.affiliation: Primate Research Institute, Kyoto University, Inuyama, Japan; Department of Developmental and Comparative Psychology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Japan Society for Promotion of Science, Tokyo, Japan. Kumamoto Sanctuary, Wildlife Research Center, Kyoto University, Kumamoto, Uki, Japan.
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Kano
authors.affiliation: Kumamoto Sanctuary, Wildlife Research Center, Kyoto University, Kumamoto, Uki, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hirata
authors.affiliation: Department of Developmental and Comparative Psychology, Max-Planck Institute for Evolutionary Anthropology, Leipzig, Germany; School of Psychology and Neuroscience, University of St Andrews, St Andrews, United Kingdom.
authors.forename: Josep
authors.initials: J
authors.lastname: Call
mesh_terms: D000818:Animals; D001288:Attention; D001522:Behavior, Animal; D005260:Female; D008297:Male; D019974:Pan paniscus; D002679:Pan troglodytes; D012919:Social Behavior