From youngsters fooling around to adults having a laugh, playing is a fact of human life. However, new findings in animal behaviour show us that play is no laughing matter. Evolutionary biologists believe it’s one of the keys to survival. And, as they’re learning, it’s not just people and pets that play, but reptiles, amphibians and insects, too. The Power of Play takes us around the world to meet the people who are turning play science into one of the most promising areas of research today. One scholar we’re introduced to is Stuart Brown, a California psychiatrist known as the “grandfather” of play research. Brown recognised play was essential to human nature as far back as 1966, finding that playing freely as a child is a key to being mentally healthy as an adult.