Language Evolution and Computation Bibliography

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.

The majority of studies on animal communication provide evidence that gestural signaling plays an important role in the communication of nonhuman primates and resembles that of pre-linguistic and just-linguistic human infants in some important ways. However, ape gestures also differ from the gestures of human infants in some important ways as well, and these differences might provide crucial clues for answering the question of how human language -- at least in its cognitive and social-cognitive aspects- evolved from the gestural communication of our ape-like ancestors. The present manuscript summarizes and compares recent studies on the gestural signaling of the great apes (Gorilla gorilla, Pan paniscus, Pan troglodytes, Pongo pygmaeus) to enable a comparison with gestures in children. We focused on the three following aspects: 1) nature of gestures, 2) intentional use of gestures, 3) and learning of gestures. Our results show, that apes have multifaceted gestural repertoires and use their gestures intentionally. Although some group-specific gestures seem to be acquired via a social learning process, the majority of gestures are learned via individual learning. Importantly, all of the intentional produced gestures share two important characteristics that make them crucially different from human deictic and symbolic gestures: 1) they are almost invariably used in dyadic contexts and 2) they are used exclusively for imperative purposes. Implications for these differences are discussed.