Play is ephemeral and versatile. Probably for this reason it is so difficult 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? © 2011 by Oxford University Press, Inc. All rights reserved.
Systematic Review of Research into the Impact of Loose
