Rough-and-tumble play as a window on animal communication

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.