This article describes research providing evidence that animals exhibit behavior that looks like “play” and discusses whether or not this behavior is representative of amusement, according to biopsychologist Gordon Burghardt’s five criteria for play.

Scientists have observed behavior from various animals that mimics human play or amusement. However, interpretation of such behavior is difficult, partly because defining the activity of play itself is unclear and the assignment of human emotion to animals is nearly impossible when the animals are unlike humans.

Nevertheless, in the last few decades researchers have documented accounts of play behavior in a variety of animals. In response, University of Tennessee biopsychologist Gordon Burghardt has established five criteria for classifying a behavior as play:

• The behavior is not fully functional.
• The behavior is spontaneous or pleasurable.
• The behavior is incomplete or exaggerated.
• The behavior is repeated.
• The behavior only occurs when the animals are well fed, healthy, and free from acute or chronic stressors.

Researchers theorize that play may help animals develop socially and cognitively, or establish dominance in socially hierarchical species. Other theories suggest that play helps juveniles develop motor skills.

Certain regions of the brain are more associated with play than others. Generally speaking, species with larger areas of the brain including the cerebellum, neocortex, hypothalamus, and amygdala tend to engage in more social play than other animals.