Monday, April 30, 2007

The evolution of gestures   posted by Razib @ 4/30/2007 03:00:00 PM

Ape gestures and language evolution:
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)...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.

It is important to remember that phylogeny does not always track morphology or ethology. After all, superficially dolphins and fish exhibit gross morphological similarities, and domestic dogs are the non-human species most sensitive to the cues and messages we send via facial expressions. The power of natural selection can utilize the extant genetic variation within disparate lineages and drive them toward cognate phenotypic conformations. So, I think we should be cautious about the insights that we can glean from studies of our nearest genetic relatives in regards to our own species' evolutionary history. In any case this work might be read with provisional paper on chimpanzee population substructure in mind.

Update: ScienceNow has a good summary.