More than a game: How play helps wire our social brains

There have been those who thought broadly about play and recognized its importance for adults. One of the first was the Dutch historian Johan Huizinga. In 1938, when he published his seminal book on play, Homo ludens, it was quite radical to argue that play was a central organizing force in human culture. But that’s what Huizinga did. 

“For many years the conviction has grown upon me, that civilization arises and unfolds in and as play,” he wrote. 

Huizinga saw play permeating language, myth, and ritual, all of which he considered root forces guiding human societies. He also developed one of the first important and lasting definitions of play. He pointed out that play is fun, it is voluntary, it’s a freedom. 

“We might call it a free activity standing quite consciously outside ‘ordinary’ life as being ‘not serious,’ but at the same time absorbing the player intensely and utterly,” he wrote. 

Anthropologists who followed Huizinga embraced his ideas. They recognized play as universal: There is no culture in the world that doesn’t play. They recognized it as therapeutic: For more than a hundred years, therapists have made use of play to heal and work through trauma. And they recognized that play was likely rooted in the evolutionary neurobiology of humans. 

Every day I see the truth in those three ideas. The last point, the biological story of play, is especially compelling because, in a sense, everything else about play springs from there. 

Play, we know now, shapes the brain. In the 1960s, a pioneering neuroscientist named Marian Diamond showed that for the first time by conducting a series of studies with rats. One group of rats was raised in cages full of toys, challenging mazes, and other rats to hang around with. The second group was raised in individual metal cages with no toys, no mazes, and no playmates. 

Diamond and her colleagues found structural and chemical differences in the brains of the rats in the “enriched” environment — the one with toys and companions. Those rats were smarter, and their brains were larger and more complex than the brains of the rats in the isolated condition. Diamond also showed that it was not just toys or playmates but the combination of the two that was essential. 

Because it was the 1960s and she was fighting to be taken seriously as a woman in science, Diamond stressed “enrichment” and avoided the word “play” to describe her findings. But, let’s be honest, what the rats in the enriched cage were doing was playing with each other and with the toys and mazes they could explore each day. 

What was happening in the rats’ brains to make them larger and more complex? From the moment babies — rat babies, human babies, and just about every other kind of baby — are born, their brains build on experience. Each experience alters the configuration of their young brains, sending electrical signals from one neuron to the next, creating networks that grow in size and efficiency the more they are used. Repeated experiences solidify those networks. As neuroscientists say, neurons that fire together wire together.

In time, brain circuits will be created for movement, for language, for reading, and everything else that is ahead in life. When experiences don’t occur, that particular set of connections won’t be made, because neurons that aren’t seeing any action get pruned away to keep our brains working efficiently. In this sense, brains are an excellent example of the use-it-or-lose-it principle. For Marian Diamond’s rats, the play in the enriched environment elicited the animals’ natural curiosity, their instinct to explore and experiment with what they found. Engaging in such activities strengthened connections between different areas of their brain. 

Jaak Panksepp, another neuroscientist, picked up where Diamond left off, beginning in the 1970s. Panksepp didn’t start out studying play; he first studied attachment and the pain and anxiety of separation in rats, but he noticed that when his rats were hanging out in their cages, they would bounce and pounce, nuzzle and nip, wrestle and pin each other. 

“When you put them together, bang! They play,” he said. “They played with such eagerness that I was blown away.” 

He began to think that the underpinnings of play and laughter in the brain might be just as interesting and informative to study as the negative emotions of pain and anxiety. “If you understand the joy of play, I think you have the foundation of the nature of joy in general,” he told Discover. 

Years of play studies followed. Panksepp used periods of isolation to make the rats hungry for play. The longer rats went without play, the more intensely they engaged in it when they got the chance — so much so that Panksepp came to think of play deprivation as akin to thirst or hunger, an alarm signal that prompts us to seek out a missing essential. Then, taking a cue from his own kids, Panksepp started tickling his rats to encourage them to play, earning him the nickname “the rat tickler” in the popular press. That’s how he worked out that the rats didn’t only play, they laughed, making ultrasonic vocalizations when they were enjoying themselves. 

Given how eagerly young rats “pursue the fun side of life,” Panksepp suspected that play was embedded in a deep and primitive part of the brain, just as attachment is. To prove it, he removed the rats’ neocortices, the outer layer of the brain responsible, in humans, for higher order thinking. Even without most of their neocortex, the rats played in a fundamentally normal way. That meant that play was a primitive process and most likely vital to survival. 

Such work made the neuroscience of play mainstream. It showed that play helps construct and refine many of the higher regions of the social brain. As Panksepp said, “Play allows us to stop, look, listen, and feel the more subtle social pulse around us.”