#18. How Play Promotes Cooperation in Adult Mammals

Play requires suppression of the drive to dominate and enables the formation of long-lasting cooperative bonds.

Dear friends,

When I go for a walk with my little dog Cookie (who would rather be called “Brutus” or anything more macho than “Cookie”) and we meet a dog he hasn’t met before, he begins barking ferociously. But if I then dare to take him off the leash, so he is free to approach the other, his mood begins to change. He seems to alternate between an aggressive posture and the submissive play posture (called the play bow) that characterizes canids generally, in which he lowers his front end while arching his neck upward. If the other dog responds to this play invitation in a similar way, I sigh with relief. There will be no fight; they will play. If I and the other dog’s owner allow the dogs to play for a while and then we meet again on another day, there is no aggressive barking. They immediately greet one another in the friendly manner of dogs (sniffing one another’s rear ends) and then begin to play.

Cookie, like all dogs, is a descendant of wolves (he likes to brag about that). Like all wolves and most of their descendants, he carries DNA that promotes aggression, but also DNA that enables him to counter the aggressive drive and form bonds of friendship. That anti-aggression DNA is the DNA for play.

Wolves in nature hunt in packs, and to do so they must cooperate in chasing down and killing large game. They form cooperative bonds through play and those bonds allow them to suppress their drives to dominate one another so they can work together to bring down an elk or other large animal. I suspect that Cookie and that other dog he met would be very bad at bringing down an elk, but their drive to play persists and is rewarded because Mother Nature (natural selection) reinforces the drive to play by hooking it up to pleasure centers in the brain.

I am now, with this letter, switching paths in this Substack. In past letters I’ve focused mostly on the roles of play in promoting the practice of life-promoting skills in young mammals, especially human children. But now I’m transitioning to a set of letters on the roles of play in adult mammals, including human adults, in enabling cooperation and peaceful social living. I begin here with an explanation of how and why play promotes cooperation

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Play Requires Suppression of Dominance Behavior

As I pointed out in previous letters (especially Letters #4, 5, and 6) the young of nearly all mammals play with one another primarily, apparently, as a means of practicing life-promoting skills. Mock fighting and chasing are the most common ways of playing for most species. A play fight is in many ways the opposite of a real fight. It may include movements and postures resembling a real fight, but the goal is opposite.

While the goal of a real fight is to end the fight as quickly as possible by winning and driving off or asserting dominance over the other, the goal of a play fight is to keep the interaction going for the pleasure and, ultimately (from an evolutionary perspective), the practice it provides. To keep it going, each animal must avoid hurting or threatening the other, that is, avoid winning or even appearing as if it wants to win. Play always requires the voluntary participation of both (or all) partners, so play is always an exercise in restraint and in retaining the other’s good will. If one player fails at that, the other will quit and the play will end (see Letter #16). Play very often involves animals that differ considerably in age, size, and strength. To keep the play going, the larger, stronger, or otherwise more dominant animal must continuously self-handicap, so as not to intimidate the other. Thus, play is always an egalitarian, cooperative activity.

Extensive research on play fighting in rats reveals that, for this species at least, the preferred positions generally are the more vulnerable defensive ones, such as the belly-up position (Pellis, 2002; Pellis & Pellis, 1998). Apparently, one evolutionary function of such play is to practice getting out of such positions. The animals typically take turns at this. The stronger one must not exert full strength against the weaker one when on top, because only when the weaker one breaks out of a pin does the stronger get to be in the vulnerable position. This too makes a play fight opposite to a real fight. In a real fight, of course, the preferred position is the dominant, attack position, and no rat in a real fight would voluntarily relinquish that position unless the other signaled defeat. Voluntary acceptance or choice of the vulnerable position distinguishes play fighting from real fighting in other species as well (Bekoff, 2004).

Similarly, in playful chasing, the preferred position for most species of animals is that of being chased rather than that of chasing, just as it is in human games of tag. (An exception occurs in the chasing play of some predatory animals, including wolves and dogs, that run down their prey. For them, chasing play appears to serve as practice in predation, and the position of pursuer appears to be at least as valued as that of being pursued.) Again, the preferred position generally is the more vulnerable one, the one that would normally be that of the subordinate or loser (in a fight) or the prey (in a predatory encounter), not that of the dominant animal. So, play reverses the preferences of agonistic encounters; in play it is better to be subordinate and vulnerable than to be dominant and invulnerable.

Play as a Foundation for Morality

Marc Bekoff (2001, 2004), who has spent a long career studying play in canids, has pointed out that, in play, animals exhibit behaviors that are considered core elements of morality when they occur in humans. These include making a deal (a social contract), trusting, behaving fairly, apologizing, and forgiving.

The play starts with some sort of signal, given by one and returned by the other, which essentially says, “Let’s not fight, mate, or ignore one another right now; let’s play.” For dogs, wolves, and other canids, the common signal for play is the play bow, which I described in the opening paragraph of this letter.  For primates, it is the relaxed open-mouth display, or play face, which is homologous to playful laughing and smiling in humans. That’s how the deal is initiated and sealed. Then, during the play, each animal must play fairly, which means abiding by the rules of not hurting or threatening the other while going through the motions of fighting or chasing. If one animal accidentally hurts another, perhaps by nipping too hard in a moment of excitement, an apology is due. The apology may take the form of backing off and again manifesting the play signal, perhaps repeatedly. Forgiveness is manifested if the nipped animal accepts the apology by returning the play bow and rejoining the play.

According to Bekoff (2004), animals rarely cheat in play, which would occur if they sealed the contract to play and then broke it by seriously attacking when the other was in a vulnerable position. Those few who do cheat—as Beckoff observed very rarely in young coyotes--tend to become social isolates and have shortened lives, because others avoid them. One function of play in animals might be to test one another’s willingness and capacity to stick to a social agreement. If you can’t stick to a play agreement, you may become a social outcast and lose the advantages that come from cooperative social activities, such as cooperation in hunting.

Final Thoughts

Although it is hard to prove empirically, my hunch is that play came about originally in mammals to serve as a vehicle for young animals to practice skills essential for survival and reproduction, including social skills as well as motor skills. However, because social play itself requires cooperation, animals had to acquire, through natural selection, means of inhibiting their innate tendencies to threaten, fight, and attempt to dominate one another in order to play. Thus, the signals for social play also became signals for non-aggression. For many species of animals, such as wolves that hunt in packs, cooperation is valuable not just for play but also for other, non=play activities. Those are the species most likely to play in adulthood.

In the next two or three letters of this series I’m going to elaborate on this idea by giving examples from the animal behavior literature supporting the thesis that the primary purpose of play in adult animals is to enable cooperation by suppressing the drive to dominate and, through that, developing long-term bonds that we might call friendships. Then, after that, I will present evidence that human cultures that foster play, including play in adulthood, are more peaceful and egalitarian than cultures that do not foster it.

As always, I welcome your thoughts and questions in the comments section below. They will add to the value of this letter. If you aren’t already subscribed to this Substack series, please do so now, and let others who might be interested know about it. By subscribing, you will receive an email notification of each new letter.

With respect and best wishes,

Peter

References

This letter draws directly from a chapter, which I wrote for an academic book a few years ago: Peter Gray.  The play theory of hunter-gatherer egalitarianism. In D. Narvaez, K. Valentino, A. Fuentes, J. McKenna, & P. Gray (Eds.), Ancestral landscapes in human evolution: culture, childrearing and social wellbeing (pp. 190-213). New York: Oxford University Press. 2014

Other references:

Bekoff, M. (2001). Social play behavior: Cooperation, fairness, trust, and the evolution of morality. Journal of Consciousness Studies, 8, 81-90.

Bekoff, M. (2004). Wild Justice and fair play: Cooperation, forgiveness, and morality in animals. Biology and Philosophy, 19, 489-520.

Pellis, S. M. (2002). Keeping in touch: Play fighting and social knowledge. In M. Bekoff, C. Allen, & & G. M. Burghardt (Eds.), The cognitive animal: Empirical and theoretical perspectives on animal cognition, pp. 421-427. Cambridge, Massachusetts: MIT Press.

Pellis, S. M., & Pellis, V. C. (1998). The structure-function interface in the analysis of play fighting. In M. Bekoff & J. A. Byers (Eds.), Animal play: evolutionary, comparative, and ecological perspectives. Cambridge, England: Cambridge University Press.