1. Play is a powerful means of practicing survival-promoting skills.
I will suggest in a future letter that this is the original, primary function of play. The young of nearly all mammals play, and research shows that they play largely at activities that are crucial to their long-term survival. Young predators play at predation—at chasing, pouncing, capturing. Young prey animals play at dodging and darting, getting away from predators. I will contend in later letters that young humans, when free to play as fully as they desire, play at all the basic skills that humans everywhere need for their wellbeing, including motor, constructive, linguistic, reasoning, social, and emotional skills.
2. Play is an engine of invention.
Play, as part of its definition, is always creative and often imaginative. In play, people come up with new ideas and creations just for fun, but some of those ideas and creations turn out to be useful in survival-promoting ways. We, more than any other species, are the animal that survives by inventing things. We can inhabit a wide variety of niches and adapt to changes in the environment because of our inventiveness, and much of that comes from play.
3. Play is a means of reducing hostility and promoting cooperation.
We are a highly social species. Our survival as individuals and as a species depends on our ability to cooperate with one another. Social play always requires the voluntary participation of both (or all) participants, so it is always an exercise in cooperation. Play brings people together and creates the friendships and mutual trust that are essential for peaceful human existence.
