Literature

The origins of language has long been discussed with little sign of any resolution. Now, "a team of researchers has rekindled an old hypothesis: that human language evolved from gesturing, rather than from vocal calls." Captive bonobos and chimpanzees were studied, to document manual gestures, facial signals and vocalisations. "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." One neuroscientist has commented: The greater variety of hand gestures "supports the idea that language evolved from manual gestures rather than animal calls".
This research has not been met with universal appreciation. Take this comment, for example: "Although all primates use vocal and facial expressions to communicate, only the great apes - chimpanzees, bonobos, orangutan and gorillas - use gestures as well, an ability they share with humans." Many people think that other animals do use gestures! Whilst manual gestures are only possible with animals having hands, gestures are possible with paws, tails, ears, fur and body posture. Maybe the reason why other animals are claimed not to use gestures is that their body language has not been formally studied. If gesturing is widespread as a means of communication, can there be any special significance of apes making gestures with limbs and hands? Human language remains a distinctive human trait.

Ape gestures and language evolution
Amy S. Pollick and Frans B. M. de Waal
Proceedings of the National Academy of Sciences USA, published April 30, 2007, 10.1073/pnas.0702624104

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.

See also:

Morell, V. The Handy Way of Speaking, ScienceNOW Daily News, 30 April 2007

Ape gestures 'show human links', BBC News, 1 May 2007.