The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


An ape's view of language and handedness: consequence, correlation or coincidence?

LINDA F. MARCHANT1 and WILLIAM C. MCGREW2.

1Department of Anthropology, Miami University, OHIO, 2Department of Archaeology and Anthropology, University of Cambridge, UK

Thursday 1:15-1:30, Grand Ballroom II Add to calendar

The temptation is perennial to link two derived conditions, language and handedness, because each is based in cerebral asymmetry. This inclination may be because both traits appear to be uniquely human characteristics, sharing a common neural substrate. However, in our species’ evolutionary past, one may have caused the other, both may be by-products of some third factor, or they may be unrelated. One way to seek to disentangle this puzzle is to look at the two conditions in our closest living relations, chimpanzee and bonobo. The current situation is murky, although all agree that fully-blown semantic and syntactic communication and right-handedness are universal in Homo sapiens. But are both features also unique to the hominin line? Two schools of thought have emerged for handedness: One sees signs of rightside-biased manual laterality in apes, while another does not. We assess critically the current evidence from Pan troglodytes and P. paniscus, using evidence from various contexts: field, lab, zoo, and sanctuary. We focus especially on gestures, that is, behavioural data on unimanual signals that occur spontaneously in ape-to-ape communication. We scrutinise data on variation within and across individuals, populations, and species. We seek to take account of methodological complications that make direct comparisons, much less experimental replications, difficult. We conclude that the evidence for species-level rightside-bias is present, but inconclusive.

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