Language Evolution and Computation Bibliography

This article highlights gesture as the most flexible modality of primate communication. An understanding of the complex issue of language evolution must be grounded in a range of disciplines, including linguistics, psychology, neuroscience, philosophy, archaeology, and primatology. The evolution of language is typically debated within a hypothetical framework, but we can look to extant non-human primate communication to help shape the discussion. One of the most interesting and least studied forms of social communication in apes is gesture. All four species of great ape that include bonobo, chimpanzee, orangutan, use their hands to communicate, but gestures are difficult to study in the wild. A notable exception is one of the first reports on gestures in wild chimpanzees studied by Goodall. The most detailed studies of gesture historically concerned human-reared individuals trained to use American Sign Language. This article reviews gestures studied in two species of great ape, chimpanzees and bonobos. The gestural origin of language theory offers a tantalizing scenario for what human language may have looked like in its early stages, and this article reviews the data on ape gestures that support this theory, or rather, a suggested modified version.

The natural communication of apes may hold clues about language origins, especially because apes frequently gesture with limbs and hands, a mode of communication thought to have been the starting point of human language evolution. The present study aimed to contrast brachiomanual gestures with orofacial movements and vocalizations in the natural communication of our closest primate relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes). We tested whether gesture is the more flexible form of communication by measuring the strength of association between signals and specific behavioral contexts, comparing groups of both the same and different ape species. Subjects were two captive bonobo groups, a total of 13 individuals, and two captive chimpanzee groups, a total of 34 individuals. The study distinguished 31 manual gestures and 18 facial/vocal signals. It was found that homologous facial/vocal displays were used very similarly by both ape species, yet the same did not apply to gestures. Both within and between species gesture usage varied enormously. Moreover, bonobos showed greater flexibility in this regard than chimpanzees and were also the only species in which multimodal communication (i.e., combinations of gestures and facial/vocal signals) added to behavioral impact on the recipient.