%A Marc Bekoff %A Colin Allen %J Animal Play: Evolutionary, Comparative, and Ecological Perspectives %T Intentional Communication and Social Play: How and Why Animals Negotiate and Agree to Play %X In these papers we mainly consider how analyses of social play in nonhuman animals (hereafter animals) can inform inquiries about the evolution of cognitive mechanisms. Social play is a good behavioral phenotype on which to concentrate for when animals play they typically perform behavior patterns that are used in other contexts (e.g. predation, aggression, or reproduction). Thus, individuals need to be able to tell one another that they do not want to eat, fight with, or mate with the other individual(s), but rather, they want to play with them. In most species (primarily mammals) in which play has been observed, specific actions have evolved that are used to initiate or to maintain play. Furthermore, sequences of play usually differ from nonplay sequences (within species) and self-handicapping has also been observed, in which, for example, dominant individuals allow themselves to be dominated _only_ in the context of play. In our consideration of how play is initiated and maintained, we discuss issues including the evolution of play, the ecology of play, the sorts of information that are shared during play, what cognitive psychologists who study humans can learn from cognitive ethologists who study other animals, and what play can tell us about the emergence of mind in animals. These essays draw on literature from ethology, psychology, and philosophy. %D 1997 %I Cambridge University Press %L cogprints156