There is a book, Animal Play; Evolutionary, Comparative and Ecological Perspectives, (Eds Marc Bekoff and John A Byers (1998)) chock full of interesting essays about the value of play – as it relates to mammalian young. So much of this book seems also to be an argument for free-play approaches to early childhood education… Some of the interesting statements from Maxeen Biben’s essay include:
“One of the most important variables governing the occurrence of play at any age is the availability of a playmate. As in most New World primates, other youngsters, not the mother, are the typical playmates. In wild squirrel monkey troops, births tend to be synchronous (Boinski 1987). Mothers stay close to one another at the time of parturition, ensuring a pool of like-aged play partners in addition to older youngsters. With peer playmates readily available, an input of time and energy by the mother (or other adults) is apparently neither needed nor provided.
The vigorous contact form of play known variously as rough and tumble, play fighting, or wrestling play predominates in squirrel monkys, as in many other mammals, as the major means of peer social interaction in the young during most of their development. Locomotor play (running, jumping, and swinging from branches or vines) also occurs but it has a heavy social component and often culminates in a bout of play fighting when one individual catches up with the other.” (p.162)
“In cultures across the world, there is a consistent finding that boys, more than girls, engage in rough and tumble play (Whiting & Edwards 1973; Humphreys & Smith 1984). Research on the play of young children has shown that gender preferences for particular styles of play interactions, utilizing different toys and games, tends to reinforce sex segregation (Erwin 1993). Girls play in small groups or pairs, learning to relate to others on an individual basis, picking up subtle social cues, and using the group as a source of support. Boys play in larger groups, are more physically active, and have more rules, goals, and physical competitiveness. Boys show little tolerance for girls’ more relaxed and informal relationships, and use their own groups as a springboard for learning to defy authority.” (p.167)
“…there is evidence to suggest that play is a priority and that youngsters (and sometimes the not-so-young) will alter their ‘normal’ or expected behavior in order to have play experiences. Such evidence, while indirect, is relevant because more direct information, as from deprivation studies, is notoriously difficult to obtain for play.
Deprivation experiments are more often than not inconclusive: those that succeed in depressing play also depress other social behavior…. [In an experiment that restricted playmate options] What we found was that animals opted to play, at a rate equivalent to that seen in a free choice social situation, regardless of the type of companions to which they were restricted. / What changed was the way in which these males played.” (p.168)
“Beckoff & Allen (Chapter 5 [this book]) have speculated that, despite the presumed deficiency of nonhuman animals in perceiving the mental states of others, play may promote learning about the intentions of others. The ability to observe, understand, and act upon the intentions of an opponent during a fight is essential. And it may be even more important to judge the intentions of a potential opponent: i.e., is he serious or bluffing, how motivated is he, is this going to be play or is it for real? Engaging in wrestling play provides both kinesthetic and cognitive cues to the partner’s (and one’s own) ability or likelihood to move from one position to another.” (p.176)
“Play fighting is by definition a contact activity, and close contact with strnagers or those whose intentions are unclear is of course another stressor. Hence the concept of ‘personal space’ and the necessity of mating rituals, greeting ceremonies, etc., to breech it. Play provides plenty of exposure to close quarters activity in an atmosphere of fun. The association with fun, as well as the repeated participation in the activity, may reduce animals’ distress at being in potentially injurious contact (whether agonistic or sexual), and give them confidence.” (p.177)
“In the conventional view of play fighting as practice for fighting, it has generally been implied that what is being learned is how to be aggressive, but there is little evidence to support this rather hasty conclusion. Instead, a more careful examination of play fighting behavior in rodents …suggests that the maneuvers used in play fights are more relevant to defense than to attack. Augmenting this view, I would here suggest that what squirrel monkeys, particularly young males, are learning in play fighting are indeed lessons relevant to fighting. These are not instruction in combat maneuvers nor are they even primarily about aggression. Instead through their play strategies, and partner choices squirrel monkeys are learning cognitive lesons relevant to social competence and self preservation, lessons of such importance that the opportunity to play can compel youngsters to disregard preferences and embrace any potential partner providing an opportunity to play, even if it means adjusting the game or play style.” (p.178)
Ref: (emphases in blue bold, mine) Maxeen Biben ‘Squirrel monkey playfighting: making the case for a cognitive training function for play’ pp161-182 in Eds Marc Bekoff and John A Byers (1998) Animal Play; Evolutionary, Comparative and Ecological Perspectives. Cambridge University Press: Cambridge, NY, Melbourne