The role of social play in juvenile behavioral development was examined in the punare (Thrichomys apereoides). Three proposed functions of social play were evaluated: 1. play serves to develop agonistic skills, 2. play has a role in the onset of weaning and 3. play establishes dominance relationships among participants.

Eight litters consisting of three juveniles and both parents were observed from birth until eight weeks of age, and the content, sequence and duration of parental and play behaviors were recorded. Adult agonism was characterized in paired encounters between. unfamiliar adults. Encounters between unfamiliar juvenile dyads were conducted and compared to litter mate play.

Sex specific differences in social play were concordant with observed differences in adult agonistic interactions. Play bouts between male juveniles were more frequent, of greater duration and incorporated more dominance reinforcement behaviors than bouts between females. Mothers tended to avoid playing with offspring, while paternal play was frequent. Self-handicapping was observed during father-daughter play. Dominance relationships were evident during play, with strong, stable hierarchies established among male juveniles. Adult males dominated all offspring and juvenile males dominated female littermates. Unfamiliar juvenile play bouts were shorter in duration and more frequently resulted in avoidance than bouts among litter mates.

These results suggest that punare social play functions to develop agonistic skills while concurrently establishing dominance relationships. The early establishment of dominance relationships may serve as a non-injurous means of precipitating male-biased post-weaning dispersal.