Goltsman (1977) predicted that in more social species there should be longer durations of social behaviours. We studied durations of 9 behavioural actions (crawling over, crawling under, allogrooming, sniffing, sideways posture, frontal posture, fighting, upright and following) in two experiments with 1-h introductions of (1) a group member that had been held in isolation for 24 h, and (2) an unfamiliar conspecific, into residental family groups of three gerbil species. Durations of some behavioural actions in these experiments were found to be longer in the most social species, Meriones libycus and M. unguiculatus. Also, we analysed the dependence of duration of agonistic interactions on the sex of the actor, the sex of the reactor, residental status of the actor and on the termination of the interaction. Species differed in the duration of three actions (sideways and frontal postures, fighting) with longer action durations in M. unguiculatus and M. libycus than in M. meridianus. These results support Goltsman's (1977) hypothesis.