ヒト科3種の比較認知科学から探る食物分配と協力社会の進化

抄録

Recent studies have revealed similarities and differences among hominids: humans, chimpanzees and bonobos. Cooperation is one of the human hallmarks, but its evolutionary basis can be found both in chimpanzees and bonobos. Comparison among the three evolutionary closest relatives would tell us about how cooperative society evolved. For this purpose, food sharing is an ideal target behavior to examine, since it is a typical cooperative behavior and prevails in the three hominids. The author has observed food sharing events among wild bonobos in Wamba, Democratic Republic of Congo. This data depicts several features of bonobos' food sharing that cannot be seen in chimpanzees. Bonobos often share plant food, which can often be obtained without any cooperation or specialized skills, sometimes even when the same food items are abundant and easily available at the sites. Bonobo recipients may beg to strengthen social bonding. Frequent plant-food sharing among bonobos may shed light on the evolution of courtesy food sharing which may be seen only in humans and bonobos.