Playing at every age: modalities and potential functions in non-human primates

Play is ephemeral and versatile. Probably for this reason it is so diffi cult to study systematically. Results from the last two decades of research suggest that play is a multifunctional phenomenon that varies according to different factors such as the species, age, sex, relationship quality of the players, etc. Accordingly, animal play needs to be studied in a comparative framework in order to rigorously assess the relative weight of various functions and contexts. Play is mainly an immature matter; however, in many mammalian species social play continues through adulthood. Therefore, a complete understanding of play can be reached by taking into account its occurrence during each phase of life. Here, I present some recent studies on primates to show that play is a response to an immediate necessity. But if so, why should it be surprising to see two adults playing together