The Grammar of Games What Play Does for Growing Brains

Five thousand years ago, somewhere along the banks of the Nile, two people sat down across from each other, placed a set of carved pieces on a decorated board, and began to play. The game was called Senet. The board had thirty squares arranged in three rows of ten. The pieces moved according to the throw of casting sticks. Nobody knows exactly what the full rules were. But we know the game existed, because archaeologists have pulled it from the dust of tombs, found it scratched into brick walls, discovered elaborate versions of it buried with pharaohs. Senet wasn't just entertainment. It was tied to religious ritual, to ideas about the afterlife, to the passage of the soul through the underworld.

And here is what that tells us: the first time in recorded history that we find clear evidence of humans playing a game, the game is already sophisticated. It already has pieces, rules, strategy, and spiritual meaning. Play didn't begin with Senet, of course. Senet is just where the archaeological trail happens to lead. The actual origin of play stretches back far beyond written records, beyond civilization, beyond the species Homo sapiens itself. It may reach back hundreds of millions of years, to the earliest creatures that ever frolicked, wrestled, or chased something for no immediately obvious reason.

That's the puzzle at the heart of this episode. Why do animals play? Why do humans, above almost all other species, play so extensively, so elaborately, and so far into adulthood? What does play actually do to the brain? And what happens when we stop?

The answers, it turns out, are not comforting when you look at modern childhood. But they are fascinating, and they matter more than almost anything else we discuss when we talk about human development.