From a biological, evolutionary perspective, the primary purpose of play is to promote skill learning. Play is nature's way of assuring that young mammals, including young humans, will practice and become good at the skills they need to develop in order to survive and thrive in their environments. The German philosopher and naturalist Karl Groos developed this idea more than 100 years ago and expanded on it in two books--The Play of Animals (1898) and The Play of Man (1901).

Young animals practice survival skills through play.

Groos was ahead of his time, both in his thinking about evolution and in his thinking about play. He understood well the writings of Charles Darwin, and he had a sophisticated, modern understanding of instincts. He recognized that animals, especially mammals, must to varying degrees learn to use their instincts. Young mammals come into the world with biological drives and tendencies (instincts) to behave in certain ways, but to be effective such behaviors must be practiced and refined. Play, according to Groos, is essentially an instinct to practice other instincts. In The Play of Animals (p 75), Groos wrote: "Animals can not be said to play because they are young and frolicsome, but rather they have a period of youth in order to play; for only by doing so can they supplement the insufficient hereditary endowment with individual experience, in view of the coming tasks of life." Consistent with his theory, Groos divided animal play into categories related to the types of skills the play promotes, including movement play (running, leaping, climbing, swinging in trees, and so on), hunting play, fighting play, and nursing play (playful care of infants).

Groos's answer to the question about the biological purpose of play allows us to make sense of the patterns of play that we see throughout the animal world. For starters, it explains why young animals play more than do older ones of the same species; they play more because they have more to learn. It also explains why mammals play more than do other classes of animals. Insects, reptiles, amphibians and fishes come into the world with rather fixed instincts; they don't need to learn much in order to survive, given their ways of life, and there is little evidence in them of play. Mammals, on the other hand, have more flexible instincts, which must be supplemented and shaped through learning and practice provided by play.

Groos's theory also explains the differences in playfulness found among different orders and species of animals. Among mammals, primates (monkeys and apes) are the most flexible and adaptable order, with the most to learn, and they are the most playful of all animal orders. Among primates, human beings, chimpanzees, and bonobos (a species of ape closely related to chimpanzees and to humans) have the most to learn, and they are the most playful species. Also among mammals, carnivores (including the dog-like and cat-like species) are generally more playful than herbivores, probably because success in hunting requires more learning than does success in grazing. Aside from mammals, the only other animal class in which play has been regularly observed is that of birds. The most playful birds are the corvids (crows, magpies, and ravens), raptors (hawks and their relatives), and parrots. These are all long-lived birds, with larger brain to body weight ratios than other birds, which exhibit much flexibility and cleverness in their social lives and ways of obtaining food.

The idea that play's purpose is to promote skill learning helps us to understand species differences in types of play as well as in amounts of play. To a considerable degree, you can predict what an animal will play at by knowing what skills it must develop in order to survive and reproduce. Lion cubs and the young of other predators play at stalking and chasing; zebra colts, young gazelles, and other animals that are preyed upon by lions and such, play at fleeing and dodging (see post on chasing games and sports); young monkeys play at swinging from branch to branch in trees. Among species in which males fight one another for access to females, young males engage in more play fighting than do young females. And, at least among some species of primates, young females, but not young males, engage in much playful care of infants.

Human children practice all sorts of skills through play, including skills specific to their culture.

In The Play of Man, Groos extended his insights about animal play to humans. He pointed out that human beings, much more so than any other species, must learn different skills depending on the society in which they develop. Therefore, he argued, natural selection led to a strong drive, in human children, to observe the activities of their elders and incorporate those activities into their play. Children in every culture play at the general categories of activities that are essential to people everywhere, but their specific forms of play, within each category, are shaped by the kinds of activities they see around them. When children are free, they play far more, and in a far greater variety of ways, than do the young of any other species because they have far more to learn.

Consistent with Groos's theory, children play in ways that promote the full range of skills that human beings everywhere must develop:

• We, like all mammals, are physical beings who must develop strong bodies and learn to move in coordinated ways, and so we have physical play, which includes chasing and rough-and-tumble games that are quite similar to the ways that other mammals play. In many other respects, however, we are unique, and our play reflects that uniqueness.

• We are the linguistic animal, and so we have language play, which teaches us to talk.

• We are Homo sapiens, the wise animal, and so we have exploratory play, which combines curiosity with playfulness to teach us about the world around us.

• We are the animal that survives by building things--including shelters, tools, devices to help us communicate, and devices to help us move from place to place--and so we have constructive play, which teaches us to build.

• We are an intensely social species, requiring cooperation with others in order to survive, and so we have many forms of social play, which teach us to cooperate and to restrain our impulses in ways that make us socially acceptable.

• We are the imaginative animal, able to think about things that are not immediately present, and so we have fantasy play, which builds and exercises our capacity for imagination and provides a foundation for what we call intelligence.

These terms, which I have put in italics, do not refer to mutually exclusive categories of play, but rather to various functions that play can serve. Any given instance of play may serve more than one of these functions. A lively outdoor group game may be physical play, language play, exploratory play, constructive play, social play, and fantasy play all at once. Play, in all its forms combined, works to build us into fully functioning, effective human beings. (For an expansion of these ideas, see post on how the varieties of play match the requirements of human existence.)

Also consistent with Groos's theory, cross-cultural studies of play have shown that children play especially at the kinds of activities that are most valued by their culture. Children in hunting and gathering cultures play at hunting and gathering, using the kinds of tools that adults in those cultures use. Children in farming communities play at animal tending and plant cultivation. Children in modern western cultures play at games that involve reading and numbers, if they grow up in settings where these are valued, and they play with computers and other modern forms of technology, the tools of today.

Going beyond Groos, I would add that children are drawn to play not just at the skills that are most prominent and valued among adults around them, but also, even more intensely, at skills that are new and expanding. Because of this, children typically learn to use new technology faster than do their parents. From an evolutionary perspective, that is no accident. At a deep genetic level, children recognize that the most crucial skills for them to learn are those that will be of increasing importance in the future--the skills of their own generation, which may be different from the skills of their parents' generation. The value of this attraction to the new is especially apparent in modern times, in which technology and the skills required to master it change so rapidly.

Play's nature suits it well to its skill-building purpose.

Play, by definition, is activity that is psychologically removed from the real world. It is activity for its own sake, not activity aimed at some serious goal outside of the play itself such as food, money, gold stars, praise, or an addition to one's résumé (see posting on the definition of play). When we offer such rewards to children who are playing, we turn their play into something that is no longer play. Because play is activity done for its own sake rather than for some conscious end outside of itself, people often see play as frivolous, or trivial. But here is the deliciously paradoxical point: Play's educational power lies in its triviality.

Play serves the serious purpose of education, but the player is not deliberately educating himself or herself. The player is playing just for the fun of playing, not for anything else; education is a byproduct. If the player were playing for a serious purpose, much of play's educative power would be lost.

Because the child at play is not worrying about his or her future, and because the child at play suffers no real-world consequence for failing--that is, because of play's triviality--the child at play does not fear failing. Because the child at play is not seeking approval or praise or gold stars or anything else from adult judges, the child at play is unhampered by evaluation concerns. Fear and concerns about evaluation tend to freeze the mind and body into rigid frames, frames that are suited for carrying out well-learned habitual activities but not for learning new actions or thinking about new ideas. In the absence of concern about failure and others' judgments, children at play can devote all their attention to the skills at which they are playing. They strive to perform well, because performing well is an intrinsic goal of play, but they know that if they fail there will be no serious, real-world consequences, so they feel free to experiment, to take risks in ways that are crucial to learning. They do not have to devote part of their mental resources to the task of trying to figure out what some external judge is looking for. They can direct their activities in ways that they are ready for, rather than in ways that some judge has chosen for them.

Another aspect of play, besides its triviality, which suits play so well for its purpose of skill building is its repetitiveness. Have you ever noticed that most forms of play involve lots of repetition? A cat playfully stalking a mouse keeps releasing the mouse in order to stalk it again. A baby playfully babbling keeps repeating the same syllables or the same sets of syllables, sometimes altering the sequence slightly, as if deliberately practicing their pronunciation. A toddler playing at walking may keep walking back and forth, over the same route. A young child playfully reading may read the same (memorized) little book, over and over again. All sorts of structured games, such as tag or baseball or twenty questions, involve repetition of the same actions or processes over and over. But the repetition is never rote.

Because the repetitive action derives from the player's own will, each repetitive act is a creative act. If the act is exactly the same as the previous act, that is because the player wished to make it the same and was striving to make it the same. Often, though, each "repeated" act is different in some systematic way from the previous one; the player is deliberately varying the act in some way to fit the game or to experiment with new ways of doing the same thing. A side effect of such repetition is the perfection and consolidation of the newly developing skill.

The same skills that children learn so naturally in play become difficult in the typical school environment. Reading is an excellent example. Many years ago I watched my youngest brother learn to read, through his own play, before he started school, and later I watched my son do the same thing. At the Sudbury Valley School, the democratic non-school school that I have described in a previous essay, countless children have learned to read through play, at a wide range of ages, sometimes completely unaware of their learning. In this age-mixed community, where there are no formal reading lessons, children learn to read because reading is a valued part of their social environment. They see other children reading and hear them talking about what they have read, so they want to read. They play games that involve the written word. They are read to by adults and teenagers, who enjoy reading to them. They want to hear the same books over and over again until they have memorized them, and then they playfully "read" the books they have memorized until their pretend reading turns into real reading.

Contrast this to learning to read in standard schools, which for many children is painful and scars them for life about reading. Imagine what it is like for the child who, for whatever reason, is a little slower at learning to read than others in the class. Reading becomes a measure of self-worth and a source of anxiety and shame, and those emotions make learning to read not only painful but hard. When children are allowed to learn to read on their own, at their own pace, through their self-directed play, reading becomes and remains one of life's great pleasures. The same is true of other skills as well. Even throwing a ball can be difficult and shame-inducing when it is taught in school rather than learned in play.

Play is nature's way of teaching us the skills we need for life. But our educational system has stupidly turned play into something called "recess," truly trivializing it and marginalizing it, and has turned learning into something called "work," making it, by definition, something that children don't want to do.


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