Discussions about play force us to reckon with our underlying ideas about childhood, sex differences, creativity and success. Do boys play differently than girls? Are children being damaged by staring at computer screens and video games? Are they missing something when fantasy play is populated with characters from Hollywood’s imagination and not their own? Most of these issues are too vast to be addressed by a single field of study (let alone a magazine article). But the growing science of play does have much to add to the conversation. Armed with research grounded in evolutionary biology and experimental neuroscience, some scientists have shown themselves eager — at times perhaps a little too eager — to promote a scientific argument for play. They have spent the past few decades learning how and why play evolved in animals, generating insights that can inform our understanding of its evolution in humans too. They are studying, from an evolutionary perspective, to what extent play is a luxury that can be dispensed with when there are too many other competing claims on the growing brain, and to what extent it is central to how that brain grows in the first place.
Scientists who study play, in animals and humans alike, are developing a consensus view that play is something more than a way for restless kids to work off steam; more than a way for chubby kids to burn off calories; more than a frivolous luxury. Play, in their view, is a central part of neurological growth and development — one important way that children build complex, skilled, responsive, socially adept and cognitively flexible brains.
Their work still leaves some questions unanswered, including questions about play’s darker, more ambiguous side: is there really an evolutionary or developmental need for dangerous games, say, or for the meanness and hurt feelings that seem to attend so much child’s play? Answering these and other questions could help us understand what might be lost if children play less.
‘‘See how that little boy reaches for a pail?’’ Stuart Brown asked one morning last fall, standing with me on the fringes of a small playground just north of the Central Park Zoo. ‘‘See how he curves his whole body around it?’’ Brown had flown to New York from his home in California to pitch a book about play to publishers. (He sold the idea to an editor at Penguin.) He agreed to meet me at the zoo while he was in town, to help me observe playfulness in the young members of many animal species, including our own.
Social play has its own vocabulary. Dogs have a particular body posture called the ‘‘play bow’’ — forelegs extended, rump in the air — that they use as both invitation and punctuation. A dog will perform a play bow at the beginning of a bout, and he will crouch back into it if he accidentally nips too hard and wants to assure the other dog: ‘‘don’t worry! Still playing!’’
Other species have play signals, too. Chimps put on a ‘‘play face,’’ an open-mouthed expression that is almost like a face of aggression except that the muscles are relaxed into something like a smile. Baboons bend over and peer between their legs as an invitation to play, beavers roll around, goats gambol in a characteristic ‘‘play gait.’’ In fact, most species have from 10 to 100 distinct play signals that they use to solicit play or to reassure one another during play-fighting that it’s still all just in fun. In humans, the analogue to the chimp’s play face is a child’s smile, an open expression that indicates there is no real anger involved even in gestures that can look like a fight.
The day Brown met me in the park was a cold one, and the kids were bundled up like Michelin Men, adding more than the usual heft and waddle to their frolicking. Even beneath the padding, though, Brown could detect some typical gestures that these 2- and 3-year-olds were using instinctively to let one another know they were playing. ‘‘Play movement is curvilinear,’’ he said. ‘‘If that boy was reaching for something in a non-play situation, his body would be all straight lines. But using the body language of play, he curves and embraces.’’
In their play — climbing up a slide, running around, passing buckets back and forth — the kids we watched were engaging in a pattern of behavior that many scientists believe is hard-wired. Their mothers and nannies were watching, too, no doubt having dragged the kids out of comfortable Upper East Side apartments because they thought daily play was important somehow, perhaps the first step in the long march toward Yale. To me all that little-kid motion looked just a bit silly — because play is, in many ways, a silly thing. Indeed, an essential component of play is its frivolity; biologists generally use phrases like ‘‘apparently purposeless activity’’ in their definitions of play. The definition proposed by Gordon Burghardt, an evolutionary psychologist at the University of Tennessee, refines that phrase a little. In his 2005 book, ‘‘The Genesis of Animal Play,’’ he wrote that play is an activity of ‘‘limited immediate function.’’
Check by next week for Part III of this great article on "Play".