Play is an accepted form of mammalian behavior, particularly in the young. However, Gordon Burghardt of the University of Tennessee claims that play is universal across the animal kingdom, in reptiles, fish and even in insects!
To establish this claim, Burghardt first had to define play, something much harder to do than it seems. Since no one is entirely sure of the purpose of play, how do you distinguish play from other activities? Burghardt decided on the following five criteria:
- Play is not fully functional in the form or context in which it is expressed.
- Play is spontaneous, voluntary, and/or pleasurable, and is likely done for its own sake.
- Play is incomplete, exaggerated, or precocious.
- Play is repeated but not in exactly the same way every time, as are more serious behaviors.
- Play is initiated when animals are well fed, healthy, and free from acute or chronic stressors.
Based on these criteria, researchers have categorized activities such as the manipulation of balls by turtles or fish as ‘play’. Jennifer Mather of the University of Lethbridge believes that octopuses squirting at floating pill bottles are being playful. Elisabetta Palagi of the University of Pisa even wonders whether off-season non-lethal dominance battles between female wasps could be a form of play-fighting.Skeptics aren’t convinced. After all, play implies a state of mind, and it’s impossible to tell what an animal is thinking when it wields an object. You can see some examples of these activities in the video below and decide for yourself whether you think the animals involved are really playing.