Pellis, S.M. & Pellis, V.C. (2007). Rough and Tumble Play and the Development of the Social Brain. Sage Journals Online: Current Directions in Psychological Science. April 2007.
Rough and tumble play, a recurring feature of childhood is correlated with measures of social competence. Play fighting involves many areas of the brain. In experiments with rats, the areas of the brain that work together to deal with social phenomena are activated. In young rats, it induces the release of chemical growth factors that affect social behavior and cognition. This article also concludes adult rats that were prevented from playing with their peers as juveniles ended up with many emotional and cognitive defects.