This book had its origins in the early 1980s, when we were working together at Cambridge University’s Sub-Department of Animal Behaviour on the developmental origins of behaviour. Our research led us to become increasingly interested in play behaviour and its role in enabling the developing organism to acquire valuable skills and experience. We promised ourselves that one day we would write a book together on the subject. However, we were also preoccupied with many other duties. Work on the present book was put off again and again, although we collaborated on two other books, one of which is now in its third edition (Bateson & Martin, 1999; Martin & Bateson, 2007). Finally, though, we started to develop our ideas about play in book form.

The different meanings given to the term ‘play’ have created much confusion and have contributed to the view that play is enigmatic and almost beyond the boundaries of science. The categorisation of play as any behaviour that is not ‘serious’ has tended to trivialise an activity that is likely to have important beneficial outcomes, both in humans and other species. We became particularly interested in the links between playfulness and creativity, and aware of the difference between generating novel forms of behaviour or ideas (creativity) and implementing worthwhile inventions in a practical way (innovation). Inevitably the book has taken on a different shape from what we had originally envisaged and the focus has enlarged to take in other aspects of human affairs. Playful play can be a serious business.