Social attention in the two species of Pan: : bonobos make more eye contact than chimpanzees
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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.
Kano , F , Hirata , S & Call , J 2015 , ' Social attention in the two species of Pan: : bonobos make more eye contact than chimpanzees ' PLoS One , vol 10 , no. 6 , 0129684 . DOI: 10.1371/journal.pone.0129684
© 2015 Kano et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
DescriptionThis study was conducted in part under FK’s post-doc program; the Japan Society for Promotion of Science (JSPS) for study abroad. FK and SH respectively received JSPS KAKENHI Grant Number 26885040 and 26245069 URL:http://www.jsps.go.jp/english/. This study was in part funded by JSPS KAKENHI Grant Number 26885040 and 26245069, MEXT KAKENHI Grant Number 24000001, JSPS-LGP-U04, JSPS core-to-core type A CCSN, and MEXT-PRI-Human Evolution.
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