Different Approaches to Meaning in Primate Gestural and Vocal Communication

Abstract

In searching for the roots of human language, comparative researchers investigate whether precursors to language are already present in our closest relatives, the non-human primates. As the majority of studies into primates’ communication use a unimodal approach with focus on one signal type only, researchers investigate very different aspects depending on whether they are interested in vocal, gestural, or facial communication. Here, we focus on two signal types and discuss how meaning is created in the gestural (visual, tactile/auditory) as compared to the vocal modality in non-human primates, to highlight the different research foci across these modalities. First, we briefly describe the defining features of meaning in human language and introduce some debates concerning meaning in non-human communication. Second, with focus on these features, we summarize the current evidence for meaningful communication in gestural as compared to vocal communication and demonstrate that meaning is operationalized very differently by researchers in these two fields. As a result, it is currently not possible to generalize findings across these modalities. Rather than arguing for or against the occurrence of semantic communication in non-human primates, we aim at pointing to gaps of knowledge in studying meaning in our closest relatives, and these gaps might be closed.

A stepping stone to compositionality in chimpanzee communication

“…First, vocal studies focus on functionally referential vocalizations, which are used in response to very specific events in the monkeys’ environment, and therefore have very specific meanings. Gestures, however, are much less specific, although it has been claimed that at least some of them have specific meanings (Hobaiter & Byrne, 2014; but see Liebal & Oña, 2018). Second, the vocal studies by Arnold & Zuberbühler (2006) and Ouattara, Lemasson & Zuberbühler (2009a, 2009b) focus on one modality only, raising the possibility that the monkeys’ communication may be even more complex, if other signal types or contextual information were taken into consideration (Wheeler & Fischer, 2012).…”

“…The determination of meaning is hampered by the fact that researchers differ drastically in terms of whether and how they assign specific meanings to signals across gestural, facial and vocal studies (Liebal & Oña, 2018). For example, vocal research has largely focused on whether primate calls have specific referents (such as specific types of predators or food), determined by the reactions of the recipients of these calls, while in the visual modalities, such as gestures and facial expressions, receiver reactions have been investigated to a much lesser extent (but see Hobaiter & Byrne, 2014).…”

The origins of gestures and language: history, current advances and proposed theories

“…see Call & Tomasello, for a literature review addressing the production and use of gestures], with only a few studies focussing on the understood gestural repertoire by addressing the meaning of gestures, i.e. what signals are used intentionally to achieve [bonobos, Pan paniscus (Graham, Furuichi & Byrne, ); chimpanzees (Roberts, Vick & Buchanan‐Smith, ; Hobaiter & Byrne, ); see also Hauser, , Scott‐Phillips, , , b ), Sievers & Gruber, and Liebal & Oña, for discussions about meaning and reference in human and non‐human animals]. While the expressed gestural repertoire refers to ‘the set of gesture types that a signaller deploys’, the understood gestural repertoire refers to ‘the set of gestures to which a recipient reacts in a way that satisfies the signaller repertoire’ (Graham, Furuichi & Byrne, , p. 171).…”

Allometry unleashed: an adaptationist approach of brain scaling in mammalian evolution

“…Second, vocalisation is only one way by which primates species communicate (Liebal et al 2013), and the intentionality component can be difficult to assess (Liebal and Oña 2018a). It would be interesting to see how gestural (Liebal and Oña 2018b) and facial (Waller and Micheletta 2013) communication, in particular, compare to Dunn and Smaers's results. Finally, those species having the smallest repertoire size also have a larger striate cortex (Figure 7b).…”