Robert 'Bob' Fagen's primary research interest is the biology of animal play. His 1981 book Animal Play Behavior remains the definitive scientific text on the subject, synthesising decades of observation and theory. His decade-long field study of play in brown bears on Admiralty Island, Alaska, produced striking longitudinal evidence that play behavior in juvenile brown bears is directly linked to long-term survival — one of the strongest demonstrations of play's adaptive value in any species. He has also studied play in birds, horses, dogs, and other mammals.
