In an article published in the April issue of Current Directions in Psychological Science, Sergio and Vivian Pellis of the University of Lethbridge reviewed multiple studies involving animals, and found a link between rough and tumble play and social competence.
For example, adult rats deprived of peer interaction, (and thus rough and tumble play), reveal an inability to comprehend the hierarchy of social structures. In the rat kingdom, when a young male attempts to establish residency in a colony, he is promptly targeted for attack by the dominant male rat. Rats that have been reared with peers quickly learn to remain crouched and motionless in such an instance in order to avoid the dominant male's attention. Play deprived rats, on the other hand, continue to scurry about which ultimately invites further serious attacks.
http://www.sciencedaily.com/releases/2007/03/070319111228.htm