A descriptive study of social development in the rat (Rattus norvegicus)

The social interactions between juvenile rat pups (Rattus norvegicus) were observed daily between 21 and 55 days of age. The data were analysed for developmental changes, sex differences, play-partner preferences, and dominance relations. The results revealed clear patterns in the development of sexual and agonistic behaviours in the rat. This development refers to changes in either the manner in which animals interact or the behaviours involved in social play, but not to the topography of specific behaviours. Development toward the adult pattern of social behaviour was temporally associated with the period of sexual maturation (i.e. between days 36 and 50).