Gestural phrases and gestural exchanges by a pair of zoo-living lowland gorillas

Previous study of the spontaneous gestural communication of the great apes has been primarily of individual gestures and their sequels. Such analysis gives only a partial picture of the quality of gorilla interaction. The repertoire of gestures of a pair of gorillas at San Francisco Zoo have been described by Tanner and Byrne (1993, 1996, 1999). These gorillas often used gestures in continuous sequences or phrases. Both single gestures and phrases were used in exchanges between gorillas. Phrases included a variety of syntactic functions, and exchanges seemed to negotiate matters such as location, initiator, and type of play. Both single gestures and phrases could be modified by “negative’ gestures. Detailed transcription of gorilla communicative events show that gestures are continually being modified and varied by the communicative partners, rather than being ritualized elements of a finite repertoire.