Orcas sank another yacht near the Iberian Peninsula in November. Members of a pod had been ramming and shaking boats in the area for more than three years, and had now sunk four. Many observers believed the orcas were attacking their boats, perhaps taking revenge on fishermen. But both boaters and scientists wondered if the orcas were playing, and the marine biologists who study this group think it may be a fad. “The consensus is that they’re doing this to show off,” the director of science at an ocean-conservation group said. (As fads do, this one may have spread; a yacht had been rammed near Scotland in June.) This is no consolation to sailors, some of whom have tried to take their own revenge on the orcas, shooting at them, lighting firecrackers, and playing heavy-metal music underwater to drive them away.
We project a great deal onto animals. They are elevated into ideals of love and fidelity (dogs, horses), and often they are reduced to objects and tools (cattle, pigs, horses again). Much of humanity’s history with animals has been made possible only by refusing to grant them inner lives anything like our own. We can be amused by a parrot’s speech and intrigued by macaques that use human hair as dental floss, but many animals live in ways we can hardly imagine. Whales and frogs and frigate birds exist in realms we cannot enter, walled off by complex sensory differences and disparate desires. We deny them the individual worth so precisely known as “personhood.” This denial doesn’t just constrict our imagination; it has also constricted research in ethology, or animal behavior.
Animal play has come into focus as a subject of study only in the past century, and the field is still developing even basic principles. What is play? How do we define it in species as different from us and from each other as octopuses and crows? The most careful observer may find it hard to avoid biases about what play looks like and means. In humans, many forms of play imitate serious behavior: hunting, courtship, exploration, building, fighting. We recognize play in other species if it looks like our own games, yet what looks like play from one perspective may be something else altogether. We may miss play entirely if it doesn’t have a human equivalent—or if it appears in an animal we don’t believe to be like us at all.
In Kingdom of Play: What Ball-Bouncing Octopuses, Belly-Flopping Monkeys, and Mud-Sliding Elephants Reveal About Life Itself, David Toomey, who teaches English at the University of Massachusetts at Amherst and writes about science, explores the research into this elusive subject. Toomey has written books about organisms living in extreme environments and about the physics of time travel, and he has a solid handle on the science here. At least 30 hypotheses of animal play are being investigated, though Toomey notes that “some are little more than notions.” He finds a definition by Gordon Burghardt, an ethologist and evolutionary biologist, particularly helpful: Play is “behavior that is nonfunctional, voluntary, characterized by repeated but varied movements, and occurring only when the animal is healthy, safe, and well-fed.”
Toomey’s own bent is toward the broader context of evolutionary biology and how play may have evolved. Clearly play provides novelty, excitement, sensation. Research suggests that human children deprived of play can develop serious difficulties. Some believe the repetitive behaviors seen in isolated zoo animals, such as pacing and rocking, may be the result of an environment barren of stimulation. Although humans tend to combine novelty, excitement, and sensation into something called “fun,” many ethologists have found the idea of “nonfunctional” behavior a serious challenge to their perspective on other species. Play promotes physical strength and group bonding, teaches social skills, and relieves stress: Therefore, in their view, play is an adaptation. They are prone to consider play as a neurological drive, an instinct, or a social response.
By David Toomey
Play-fighting, one of the most common forms of social play in the world, is a good example. Humans do it, of course; it explains everything from the brutal red-rover games of my childhood to Call of Duty. Magpies play-fight too. So do capuchins, gorillas, meerkats, voles, and gerbils. Kangaroos engage in formal boxing matches, their bouts beginning only after one has accepted an invitation from another. Rats spar in a series of gentle attacks, escapes, and counterattacks; most of the time, nobody gets hurt. We can see a dozen different skills at work.
But many animals also engage in behaviors with no obvious benefit—which doesn’t deter the scientific quest to find one, Toomey observes. Piglets often run around and occasionally perform a kind of flip. Researchers have been inclined to see this as skill-building. “We hypothesize,” as one group put it, “that a major ancestral function of play is to rehearse behavioral sequences in which animals lose full control of their locomotion, position, or sensory/spatial input and need to repair those faculties quickly,” a routine that the group called “training for the unexpected.” In other words, Toomey writes, “the piglet undertakes the flop-over not for its own sake, but in anticipation of the moment immediately after the flop-over when it recovers and regains control.” Bemused, he adds that most observers recognize that a somersault appears “thrilling” to piglets—and that falling down seems to be the point.
The search for utility sometimes fails, which can frustrate ethologists intent on discovering “adaptive advantages.” Toomey describes the way South American fur-seal pups in Punta San Juan will goof around in tidal pools even though this risks an attack by sea lions—just one example of overtly dangerous forms of play. Describing the conundrum presented by a puppy in the snow, he drily writes, “The puppy’s pleasure is self-evident but, for many hypotheses of animal play, difficult to explain. The puppy will find its movements inhibited and, if the snow is deep enough, its vision compromised. How can that be fun?”
Toomey offers other examples of animal behavior that appears “nonfunctional.” Many people have reported watching elephants slide down muddy embankments, appearing to deliberately collide with other elephants climbing up. Then they do it again. Describing a turtle that shared a tank with a nurse shark, Toomey notes that, now and then, the turtle would carefully bite the shark’s tail just hard enough that the shark pulled the turtle around as it swam. A group of 45 bees was allowed to walk along a path that offered both food and small wooden balls. Individual bees stopped and pushed the balls back and forth. Some bees did it only once, but others came back for weeks to roll the balls again and again.
When you pause to think about it, the array of behavior that confounds ready categorizing as adaptive is delightfully broad. Before orcas began ramming yachts, they had what appeared to be a fashion trend of wearing dead fish on their heads. Songbirds sometimes sing when they are alone, repeating a phrase or trill several times; they seem to be singing simply for the sake of it. I had a golden retriever who would drop his beloved tennis ball in the eddy of a fast river and nudge the ball to the very edge of the current, waiting until the last possible chance to snatch it out. A grainy video online of a crow in Russia shows the bird carrying a jar lid to the peak of a roof, climbing in, and snowboarding down. The crow does this several times. Toomey describes a group of common eiders gliding down a river’s rapids and hurrying back to the spot from which they began to have another go. Perhaps if you can fly, sliding is peculiarly exciting.
Toomey calls this kind of activity “tinkering,” an expression of “the craving for fun or sensation” in testing the ways of the world. He describes a raven who picked up a small rock and worked it to the edge of a cliff. The bird gazed down the side of the cliff, then pushed the rock off and watched it fall. It went to get another rock, repeating this in front of observing scientists who were stymied in their search for the behavior’s utility. Toomey is less bewildered.
You approach a ledge. You look down. Having no pressing appointments, you pick up a small stone and toss it over. You watch it fall, bounce off an outcropping, and hear it hit bottom. Then you do it again. Perhaps the answer to why the raven was dropping the stones is the reason you and I might do it. What is that reason?
It’s … fun.
The theorists can be a bit dispiriting. Sometimes I wanted to whack one on the side of the head and say, “Hey, catch this ball.” The quest for objectivity will sooner or later collide with the fact that in the kingdom of play, humans have plenty in common with other animals. We naturally romp with dogs. And dogs goof around with horses. Rats enjoy being tickled. The so-called play expression is common—a “relaxed open-mouth display.” Is it possible to see this as a smile? That puppy in the snow: If you can’t appreciate the fun of having your movements inhibited and your vision compromised by a weird substance, then I don’t want to go to a foam fight or costume party with you.
Wry though Toomey can be about the somber ethology crowd, his own writing is sometimes dense. Evolutionary biology is the spine of his book, and his last chapters lean hard into the exegesis of theories, leaving the anecdotes promised by his popular-market subtitle behind. He loses the reader at times in a discussion invoking master genes and cladistics (a system of biological taxonomy) that aims to fit animal play into natural selection. And once he gets deep into evolutionary biology, the words possible and imagine come up a lot. We don’t know—likely can never know—how behavior evolved over tracts of time beyond our ken.
Plenty of questions remain. Many ethologists these days are willing to consider consciousness and emotion in animals, and that means anthropomorphism can interfere once again. Almost all the research into animal play has involved familiar placental mammals, such as primates and canids. Play has been observed in several species of reptiles and fish, but they still get little attention from researchers. Maybe many animals, like a few humans, don’t play. “I think it more likely, though,” Toomey writes, “that animals are all the time behaving in astonishing ways that we simply fail to notice.”
In the end, the belief that animals are no less complex and mysterious than humans prevails in Kingdom of Play. Toomey understands that if we always reduce play to some form of utility, we are returning animals to the status of automatons. As the book winds down, his own enjoyment of the subject comes to the fore. He follows a few unexpected tangents, among them several stories about people whose deep sense of wonder at the lives of other species inspires them to extreme attempts at immersion in their existence. He describes a man who lived among goats in Switzerland, wearing hoof prostheses on his hands and feet and going on all fours, and a British veterinarian who tried to share in the aroma-rich world of a badger by crawling in the grass, smelling the ground as he moved. He ate earthworms for a time. We may ever be in the dark about animals’ inner lives, but how much darker life is if we turn away because of that.
Of course, the real question isn’t whether animals play, but how to understand what is happening when they do. If we can conceive of an animal simply having fun, we can no longer see animals as mere objects. We are challenged to change the way we treat them, and a solemn responsibility is added to our dominion. Somersaulting may be good training for the unexpected, but I wonder: Why is it so hard to believe that exuberance is in itself a good?
We can meet our fellow animals in the most surprising ways. An orangutan watches a person perform the cup-and-ball trick, putting a ball inside one of several cups, overturning them, and shuffling them around. The animal observes closely, Toomey writes, “until the performance’s conclusion, when it is shown that the cup it thought would hold a ball is empty. Staring into the cup, confirming that against expectations it is empty, the orangutan rolls onto its back with obvious delight.” The orangutan is not just playing. It has been played, and finds this to be an excellent joke.
This article appears in the April 2024 print edition with the headline “Why Do Animals Play?”
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