Summary: Montgomery (2014)

 Many mammals, including primates, play. Play includes those behaviours that appear incompletely functional, atypical, spontaneous and repeatable, and are elicited under conditions of low stress. Play is easy to recognize, but is often difficult to define. Play is primates occurs often, although nonadaptive and adaptive explanations for its occurrence are plentiful. In primates, social play has been linked to the relative size of various brain regions, including the neocortex, amygdala, cerebellum and hypothalamus, suggesting that play is involved in the development of cognition. These structures have also been shown to be involved in the ability to first predict, and then perform, sequential actions, indicative of behavioural flexibility. Using data on the frequency of social and nonsocial play in various primates, Montgomery (2014) attempted to find evidence that could directly link play to behavioural flexibility and/or brain maturation. He found that postnatal brain growth increased with the frequency of play and that measures of behavioural flexibility are associated with the frequency of play. Montgomery (2014) concluded by indicating that the results from this study provide an adaptive framework for play.