In The Genesis of Animal Play, Gordon Burghardt examines the origins and evolution of play in humans and animals. He asks what play might mean in our understanding of evolution, the brain, behavioral organization, and psychology. Is play essential to development? Is it the driving force behind human and animal behavior? What is the proper place for the study of play in the cognitive, behavioral, and biological sciences? The engaging nature of play—who does not enjoy watching a kitten attack a ball of yarn?—has made it difficult to study. Some scholars have called play undefinable, nonexistent, or a mystery outside the realm of scientific analysis. Using the comparative perspectives of ethology and psychology, The Genesis of Animal Play goes further than other studies in reviewing the evidence of play throughout the animal kingdom, from human babies to animals not usually considered playful. Burghardt finds that although playfulness may have been essential to the origin of much that we consider distinctive in human (and mammalian) behavior, it only develops through a specific set of interactions among developmental, evolutionary, ecological, and physiological processes. Furthermore, play is not always beneficial or adaptive. Part I offers a detailed discussion of play in placental mammals (including children) and develops an integrative framework called surplus resource theory. The most fascinating and most controversial sections of the book, perhaps, are in the seven chapters in part II in which Burghardt presents evidence of playfulness in such unexpected groups of animals as kangaroos, birds, lizards, and "Fish That Leap, Juggle, and Tease." Burghardt concludes by considering the implications of the diversity of play for future research, and suggests that understanding the origin and development of play can shape our view of society and its accomplishments through history. The open access edition of this book was made possible by generous funding from Arcadia – a charitable fund of Lisbet Rausing and Peter Baldwin.

There has been a recent resurgence of interest in the study of play behavior, marked by much empirical research and theoretical review. These efforts suggest that play may be of greater biological significance than most scientists realize. Here we present a brief synopsis of current play research covering issues of adaptive function, phylogeny, causal mechanisms, and development. Our goal is to selectively highlight contemporary areas of research in which the underlying processes and consequences of play should not be ignored. We elucidate some of the new and burgeoning areas of play research and interpret them from an integrative biological theoretical perspective that highlights areas in need of further experimental, comparative, and field research.

No abstract

In studies of squamate responses to prey chemicals presented on cotton-tipped applicators, investigators typically record several responses, each of which gives only part of the overall picture. The tongue-flick/attack score (TFAS) is a widely used composite measure of response strength that accounts for attack, its latency, and number of tongue-flicks. We present data and analyses on these variables and investigate the utility of several other possible response variables. It is concluded, for both practical and theoretical reasons, that TFAS and two modifications of it are the best measures of response strength. Uses and statistical analyses of TFAS and variables derived from it are discussed. It is recommended that information on tongue-flick rate, number of individuals attacking, and latency to attack be presented.

Rough-and-tumble play (RT) is a widespread phenomenon in mammals. Since it involves competition, whereby one animal attempts to gain advantage over another, RT runs the risk of escalation to serious fighting. Competition is typically curtailed by some degree of cooperation and different signals help negotiate potential mishaps during RT. This review provides a framework for such signals, showing that they range along two dimensions: one from signals borrowed from other functional contexts to those that are unique to play, and the other from purely emotional expressions to highly cognitive (intentional) constructions. Some animal taxa have exaggerated the emotional and cognitive interplay aspects of play signals, yielding admixtures of communication that have led to complex forms of RT. This complexity has been further exaggerated in some lineages by the development of specific novel gestures that can be used to negotiate playful mood and entice reluctant partners. Play-derived gestures may provide new mechanisms by which more sophisticated communication forms can evolve. Therefore, RT and playful communication provide a window into the study of social cognition, emotional regulation and the evolution of communication systems.