Great ape gestures: intentional communication with a rich set of innate signals

Abstract

Great apes give gestures deliberately and voluntarily, in order to influence particular target audiences, whose direction of attention they take into account when choosing which type of gesture to use. These facts make the study of ape gesture directly relevant to understanding the evolutionary precursors of human language; here we present an assessment of ape gesture from that perspective, focusing on the work of the “St Andrews Group” of researchers. Intended meanings of ape gestures are relatively few and simple. As with human words, ape gestures often have several distinct meanings, which are effectively disambiguated by behavioural context. Compared to the signalling of most other animals, great ape gestural repertoires are large. Because of this, and the relatively small number of intended meanings they achieve, ape gestures are redundant, with extensive overlaps in meaning. The great majority of gestures are innate, in the sense that the species’ biological inheritance includes the potential to develop each gestural form and use it for a specific range of purposes. Moreover, the phylogenetic origin of many gestures is relatively old, since gestures are extensively shared between different genera in the great ape family. Acquisition of an adult repertoire is a process of first exploring the innate species potential for many gestures and then gradual restriction to a final (active) repertoire that is much smaller. No evidence of syntactic structure has yet been detected.

Multimodal communication and language origins: integrating gestures and vocalizations

“…Arnold & Zuberbühler, ), as opposed to the redundancy present in the ape gestural repertoire (e.g. Byrne et al, ).…”

“…By contrast, studies on wild communities provided evidence that the available repertoires are largely innate and species‐typical (Genty et al, ; Hobaiter & Byrne, ; Graham, Furuichi & Byrne, ). After a lively debate on the mechanisms of gesture acquisition, several researchers concluded that the forms of gesture types (the ‘tool‐set’ or available repertoires) are largely genetically anchored (Byrne et al, ), whereas their usage in relation to their context and social environment (the ‘tool application’) is affected by interactional experiences throughout life (Bard et al, ; Fröhlich & Hobaiter, ; Liebal, Schneider & Errson‐Lembeck, ; Pika & Fröhlich, ). Early gestural communication in chimpanzees, for instance, is influenced by the number of interaction partners and interaction rates with non‐maternal conspecifics (Fröhlich et al, ).…”

“…Hewes, ; Corballis, ; Armstrong & Wilcox, ). Since a remarkable number of gesture types in the naturally used repertoire is shared among genera and species, they are thought to be phylogenetically quite old (Byrne et al, ). What historically began with a focus on manual gestures limited to movements of the upper extremities in enculturated apes trained to use sign language (Gardner & Gardner, ; Premack & Premack, ; Patterson, ) has gradually expanded to include most of the bodily communication of primates.…”

Cross-species referential signalling events in domestic dogs (Canis familiaris)

“…This is in contrast to findings in great apes where repertoire size is negatively related to age (Genty et al 2009; Hobaiter and Byrne 2011). There it is proposed apes gradually learn which gestures from a portfolio work best and so omit superfluous ones with experience (Byrne et al 2017). With the so-called ‘redundancy’ taking place adult apes consequently demonstrate fewer gestures.…”

Crossing the Rubicon: Behaviorism, Language, and Evolutionary Continuity

“…Attempts to teach great apes to talk have largely failed, but greater success has been achieved using simplified forms of sign language (Patterson and Gordon, 2001) or keyboards containing arrays of word-like symbols (Savage-Rumbaugh et al, 1998). Byrne et al (2017) list 84 different communicative gestures arising from the studies of great apes' gestures, and note that they are goal directed and intentional, unlike most primate calls. To be sure, there is little evidence for sentence-like structure, but chimpanzee gestures suggest a natural platform for more complex sequences.…”