Apes Point to Language Origins

April 30, 2007

Apes’ use of hand and limb signals, or gestures, to communicate may help illuminate the origins of human language, new research suggests. Although all primates use their voices and facial expressions to communicate, only humans and apes have free manual gestures in their communicative repertoire. However, little is known about how these signals combine with other forms of communication and how their use affects the response of others. Amy Pollick and Frans de Waal report that our closest primate relatives, bonobos (Pan paniscus) and chimpanzees (Pan troglodytes), use gestures differently from the way they use facial/vocal signals. Facial/vocal signals were tied to specific contexts and used similarly across species and groups. Gesture usage, however, was so flexible that it could not be generalized from species to species – or even from group to group within the same species. Bonobos used gestures most flexibly, adding gestures to complement vocal and facial signals. These combinations were more effective in getting a response from the recipient, e.g., obtaining food by extending an open hand. These findings fit the “gestural hypothesis” of language origin, which suggests that human language evolved in the gestural domain before it involved the spoken word.

Abstract © 2007, PNAS

“Ape gestures and language evolution,” Amy S. Pollick, Frans B. M. de Waal, April 30, 2007

Frans B. M. de Waal, Yerkes National Primate Research Center, Emory University