Differences in Variability, Interactivity and Skills in Social Play of Young Chimpanzees Living in Peer Groups and in a Large Family Zoo Group

Abstract

Abstract This paper provides a detailed comparison of play characteristics of chimpanzees raised in peer-only groups and in a socially complex semi-natural zoo situation. We expected play in peer groups to be of a lesser quality, that is less variable, interactive and skillful. To test this we quantified details such as the diversity of social play types, the bout length, the way social play is started, maintained and stopped and the use of play signals. The differences in play-type frequencies between the groups are most likely caused by differences in housing conditions and demographics; the smaller sex difference in peer group adolescents is most likely due to a limited partner choice. We found no indication that chimpanzees raised in peer groups played less diversely than those in the zoo. The social play characteristics of peer group and zoo chimpanzees are similar, except for the frequency of gnaws before wrestle and the frequency of play-faces within wrestle. Overall, there are no results from which we can conclude directly that chimpanzees isolated from their mother at an early stage and placed in a peer group are less capable in social play, although possibly it is more clear to the zoo individuals that a next interaction will be 'play'; zoo individuals may need less regular removal of ambiguity about the intention of the behaviour. The few differences between peer group and zoo in their social play characteristics that can be related to peer group rearing conditions indicate that the social development in those chimpanzees raised in peer groups is similar to that of chimpanzees in the semi-natural zoo. This is not to say that providing more natural conditions than is usually done in laboratories is unnecessary. These may still add considerably to the animals' well-being and in terms of animal welfare, it can be concluded that a variety of partners in the housing condition is beneficial to speed of sex-role development in young chimpanzees.