As humans, we have a tendency to divide our lives into the distinct categories of work and play. Work is viewed as essential—the daily effort of earning a living, raising a family—while play is frivolous, something to do in one’s spare time or the purview of children. Despite the societal constraints that try to tell us that play is unimportant, evidence suggests the opposite.
For a long time, our desire to see ourselves as different from other species led us to believe that humans were the only animals engaging in purposeful play. Even today, our framework for animal behaviour insists that other species only engage in activities that provide benefits—either in a cost benefit analysis of energy resources or as a genetic legacy. Animals, or so the theory goes, do not act without rational purpose, even if that purpose is innate.
Play (along with altruism) confounds that theory. For a long time, play was thought to offer learning experiences to young animals. Through play, lion cubs would learn to hunt or baby monkeys would learn to climb. So far, the research doesn’t support this theory. First, many species continue to engage in play in adulthood and second, studies show no learned benefits for youngsters who engaged in play versus those who didn’t. Even among humans, the connection between learning and play is tenuous.
Our desire to be objective observers has caused us to question if we can recognize play in other species. Does play exist or are we simply anthropomorphizing and projecting our own experience onto other animals? The philosophical answer suggests we recognize play in other animals because we are part of, not separate from, nature and we have a shared experience. Scientifically speaking, researcher Gordon Burghardt identified five criteria to help identify play in animals (quoted from Testing the Limits by Angie Vickers):
Play is not fully functional in the context of its expression (like a kitten attacking a toy mouse that is not edible).
Play is spontaneous, pleasurable, rewarding, or voluntary.
Play is different from other more serious behaviors in form or timing (like play fighting in puppies).
Play is repeated, but not in the exact same way every time.
Play is initiated when animals are well fed, healthy, and free from stress.
Using Burghardt’s criteria, we’ve gradually come to accept that other mammal and bird species like to play. Whether it’s otters sliding down a snowy bank or juggling rocks or crows playing with a stick and piece of string, animal play is all around us. This is definitely true for the animals we choose to share our homes with—billions of dollars of toy mice and tennis balls litter the floors of every cat and dog owner.
Play is also found in unexpected species such as crocodiles, who like to both slide and play with toys. Even insects engage in play, with female wasps engaging in play-fighting or spiders who engage in play during courtship. Captive octopuses are also well known for playing with toys in their tanks, although interestingly, wild octopuses are less likely to play as their time is spent hiding and eating.
Even with established criteria, observational evidence, and our own desire to play, scientists still don’t fully understand why we play. The best evidence suggests that play helps with problem-solving and stress relief. Experiments with rats—some of the most playful creatures—show that when rats are deprived of play, they lose their ability to chill out in stressful social situations.
Regardless of our reasons, we know that having fun, which is what play is, releases dopamine, giving our brains a pleasure reward. It seems possible that this is true for animals as well. Like us, they play because it’s fun, which might be the only reason they need.