The social play behavior of the bonobo (Pan paniscus) was studied in a provisioned group at Wamba, Zaire. Case studies revealed characteristics of the play of this species. (1) An older female participated in a play of make-believe with a young adult male. (2) There were cases in which an adult or adolescent male did play with an infant or a juvenile. A possibility of the existence of a mechanism that conveys information from a generation to another were discussed. (3) Play behavior among adult and adolescent males were observed, and in some case the play functioned resolve tensions among them. (4) Various types of sexual play were observed, from typical play to play-like solicitations. The concept of “field of interaction”, that is determined by “relation structure”, was presented and “play field” was discussed. The position of play in a coordinate with axes of degrees of freedom in relationship among individuals and in behavioral patterns were discussed. The intimate relation between play and human language in the coordinate were emphasized. It was asserted that play is one of the most interesting phenomena for primatologists to study.
