アフリカの類人猿

生態・社会の比較と課題

抄録

A Comparison of the ecological characteristics and social structure among three species of African great apes have been discussed. T. Kano brought the first ecological data of pygmy chimpanzees (Pan paniscus) last year. He indicated several specific features in the food habit, behaviour and grouping of this species. General remarks on this species seem to be more similar to chimpanzees (P. troglodytes) than to gorillas (P. gorilla). However, the data are not enough in comparing the social structure of pygmy chimpanzees with that of chimpanzees and gorillas. In this paper, I tried to contrast chimpanzees with gorillas especially in the habitat, food habit, spacing of unit-groups and social structure. In spite of the long-termed studies of chimpanzees, the sustaining mechanism of their social structure remains unexplained. I presumed four possible types of the structure on the basis of the data which have been collected so far. Clarifying the life history of male chimpanzees and the functions of male-bonding in unit-group of chimpanzees should be very important problems for the future studies. Recently Dian Fossey has made it clear that the society of gorilla rotates by means of kidnapping of young females by a male. Although the two societies have a common feature that they are neither matrilineal nor patrilineal, the social structure of both species is conspicuously different. If they were derived from a common ancestor, more detailed comparative studies of the ecology, behaviour and social structure should solve riddles of speciation process of both species, chimpanzees and gorillas.