Our taxonomic name, homo sapiens, identifies us as thinking beings. However, our distinctiveness does not lie exclusively in the mind—a point social scientists have often emphasized by offering new appellations for our species. Two of the more interesting of these, used by competing scholars during the mid-20th century, designate us as “makers”—homo faber—and as “players”—homo ludens. As makers, we labor to improve our environments, often ingeniously with tools. Our work defines us. As players, by contrast, we shape our existence in less utilitarian pursuits—leisure and recreation. So our play also defines us.

At first, homo ludens seems to be the more intriguing classification, but it may not really distinguish us. After all, hardly any other creature uses tools or ma...