A new theory about early human adaptation suggests that our ancestors capitalized on their capacities for play to enable the development of a highly cooperative way of life.

Boston College developmental psychologist Peter Gray suggests that use of play helped early humans to overcome the innate tendencies toward aggression and dominance which would have made a cooperative society impossible.

"Play and humor were not just means of adding fun to their lives," according to Gray. "They were means of maintaining the band's existence - means of promoting actively the egalitarian attitude, intense sharing, and relative peacefulness for which hunter-gatherers are justly famous and upon which they depended for survival."

This theory has implications for human development in today's world, said Gray, who explains that social play counteracts tendencies toward greed and arrogance, and promotes concern for the feelings and wellbeing of others. "It may not be too much of a stretch," says Gray, "to suggest that the selfish actions that led to the recent economic collapse are, in part, symptoms of a society that has forgotten how to play."

Interest in play is very much on the upswing among psychologists, educators, and the general public, according to Gray. "People are beginning to realize that we have gone too far in the direction of teaching children to compete," he said. "We have been depriving children of the normal, noncompetitive forms of social play that are essential for developing a sense of equality, connectedness, and concern for others."

Gray stressed that the kind of "play" that helped hunter-gatherer children develop into cooperative adults is similar to the sort of play that at one time characterized American children's summers and after-school hours in contemporary culture. This play is freely chosen, age-mixed, and, because it is not adult-organized, non-competitive, he said. This "free play" is distinct from leisure pursuits such as video games, watching TV, or structured extracurricular activities and sports.

"Even when children are playing nominally competitive games, such as pickup baseball or card games, there is usually relatively little concern for winning," said Gray. "Striving to do well, as individuals or teams, and helping others do well, is all part of the fun. It is the presence of adult supervisors and observers that pushes play in a competitive direction--and if it gets pushed too far in that direction it is no longer truly play."

The most important skill for social life, Gray said, is how to please other people while still fulfilling one's own needs and desires. In self-organized play, he contends, children learn to get along with diverse others, to compromise, and to anticipate and meet others' needs. "To play well," he said, "and to keep others interested in continuing to play with you, you must be able to see the world from the other players' points of view.

"Children and teenagers in hunter-gatherer cultures played in this way more or less constantly," he said, "and they developed into extraordinarily cooperative, egalitarian adults. My observations - published in previous articles - indicate that age-mixed free play in our culture, in those places where it can still be found, has all of these qualities."

Gray's article addresses not just children's play, but also play as a fundamental component of adult human nature, which allowed humans to develop as intensely social and cooperative beings. Through the course of his research, he said, it became increasingly apparent that play and humor lay at the core of hunter-gatherer social structures and mores.

Hunter-gatherers used humor, deliberately, to maintain equality and stop quarrels, according to Gray, and their means of sharing had game-like qualities. Their religious beliefs and ceremonies were playful, founded on assumptions of equality, humor, and capriciousness among the deities. They maintained playful attitudes in their hunting, gathering, and other sustenance activities, partly by allowing each person to choose when, how, and how much they would engage in such activities.

"Professor Gray's novel insight sheds new light on the question of how such societies can maintain social harmony and cooperation while emphasizing the autonomy of individuals," said Kirk M. Endicott, a leading anthropologist and hunter-gatherer expert at Dartmouth College. "Conversely, his demonstration of the wide-ranging role of play in hunter-gatherer societies focuses attention on the importance of play in the evolutionary success of the human species."

Peter Gray has been a professor of psychology at Boston College for more than 35 years. In 2002 he retired from the position of full professor and assumed the position of research professor. He is the author of "Psychology," a widely-used psychology textbook now in its 5th edition, and has published a number of scholarly articles on the role of play in education.

He frequently speaks on play and education at national conferences and university colloquia, and is currently one of seven members of a nation-wide think tank on improving education through the lens of an evolutionary perspective.