Gestural communication of the gorilla (Gorilla gorilla): repertoire, intentionality and possible origins

Abstract

Social groups of gorillas were observed in three captive facilities and one African field site. Cases of potential gesture use, totalling 9,540, were filtered by strict criteria for intentionality, giving a corpus of 5,250 instances of intentional gesture use. This indicated a repertoire of 102 gesture types. Most repertoire differences between individuals and sites were explicable as a consequence of environmental affordances and sampling effects: overall gesture frequency was a good predictor of universality of occurrence. Only one gesture was idiosyncratic to a single individual, and was given only to humans. Indications of cultural learning were few, though not absent. Six gestures appeared to be traditions within single social groups, but overall concordance in repertoires was almost as high between as within social groups. No support was found for the ontogenetic ritualization hypothesis as the chief means of acquisition of gestures. Many gestures whose form ruled out such an origin, i.e. gestures derived from species-typical displays, were used as intentionally and almost as flexibly as gestures whose form was consistent with learning by ritualization. When using both classes of gesture, gorillas paid specific attention to the attentional state of their audience. Thus, it would be unwarranted to divide ape gestural repertoires into 'innate, species-typical, inflexible reactions' and 'individually learned, intentional, flexible communication'. We conclude that gorilla gestural communication is based on a speciestypical repertoire, like those of most other mammalian species but very much larger. Gorilla gestures are not, however, inflexible signals but are employed for intentional communication to specific individuals.

Social play as joint action: A framework to study the evolution of shared intentionality as an interactional achievement

“…arm shake (Tanner, 2004). Once shared attention is established, one-handed grab is commonly used to initiate contact play, whilst drum object is used to initiate chase-play (Genty, Breuer, Hobaiter, & Byrne, 2009). During the main body phase of play, playfaces and laughter serve to maintain play .…”

“…To re-engage partners following interruptions, individuals animate objects and show them to partners to re-establish mutual attention toward the game (Tanner & Byrne, 2010). In the closing phase, to exit from play, gorillas use handon and pirouette gestures (Genty et al, 2009;Luef & Liebal, 2013).…”

A word in the hand: action, gesture and mental representation in humans and non-human primates

“…Subsequent studies have recorded species repertoires of up to 100 gesture types (e.g. [76]), but these differences can largely be attributed to how narrowly each gesture type is defined in each study [77].…”

Adaptable individuals and innovative lineages

“…There is, for example, a debate on the extent to which great ape communication traditions can be explained by ritualization; an associative mechanism that shapes an initially functional act into a signal; turning a grab into a begging gesture. There are great ape gestural practices which seem not to have plausible origins in associative learning [51]. Likewise, the motivational contexts and constraints on social innovation seem different from those that constrain ecological innovation.…”