Play

Play behavior is relatively rare in the animal kingdom, but is widespread, and in some lineages is very common not only in childhood but also in adulthood. It can take many forms, as playful actions can be directed to a social partner (social play), to an inanimate object (object play), or self-directed, as the animal, jumps, runs, and turns (locomotor-rotational play). Considerable progress has been made in understanding the neural, emotional, and cognitive mechanisms mammals use in regulating social play, but whether comparable mechanisms are used to regulate other forms of play, or apply to non-mammalian animals, remains to be resolved. Similarly, social play in some mammals has been demonstrated to benefit the development of sociocognitive skills and emotional resilience, while locomotor-rotational play can benefit the development of motor skills. The factors that allow some species to gain these benefits also remain to be resolved. Statistical approaches that take the relatedness of species into account are increasingly being applied to analyze a growing comparative database that includes species from many different lineages. In addition, mathematical and computational models are being used to test the explanatory power of various factors to account for the evolution of play. Coupled with new methods in neuroscience that provide a deeper understanding of the brain during play, these approaches will enable extraordinary progress in understanding play over the next few decades.