Metacommunication in social play: the meaning of aggression-like elements is modified by play face in Hanuman langurs (Semnopithecus entellus)

The metacommunication hypothesis asserts that some elements of play behaviour are associated with play elements borrowed from aggression and interpret these aggression-like elements as playful. Using data from free living Hanuman langurs (Semnopithecus entellus), we tested three predictions that follow from the metacommunication hypothesis: (i) aggression-like elements (ALEs) abbreviate play bouts; (ii) candidate signal elements are sequentially associated with ALEs; (iii) associations of candidate signal elements with ALEs prolong play bouts. Play face and five other candidate signal elements were evaluated in relation to nine ALEs. We confirmed all three predictions for play face, albeit only if the play face and/or the ALEs occurred at the start of the play bout. The other candidate elements were not associated with ALEs. We conclude that play face fulfils the metacommunicatory function in Hanuman langur play bouts, while other play specific elements may serve other signal or non-signal functions.