Right-Handed Chimpanzees Provide Clues To The Origin Of Human Language


Most of the linguistic functions in humans are controlled by the left cerebral hemisphere. A study of captive chimpanzees at the Yerkes National Primate Research Center (Atlanta, Georgia), reported in the January 2010 issue of Elsevier’s Cortex, suggests that this “hemispheric lateralization” for language may have its evolutionary roots in the gestural communication of our common ancestors. A large majority of the chimpanzees in the study showed a significant bias towards right-handed gestures when communicating, which may reflect a similar dominance of the left hemisphere forcommunication in chimpanzees as that seen for language functions in humans.

A team of researchers, supervised by Prof. William D. Hopkins of Agnes Scott College (Decatur, Georgia), studied hand-use in 70 captivechimpanzees over a period of 10 months, recording a variety of communicative gestures specific to chimpanzees . These included ‘arm threat’, ‘extend arm’ or ‘hand-slap’ gestures produced in different social contexts, such as attention-getting interactions, shared excitation, threat, aggression, greeting, reconciliation or invitations for grooming or for play. The gestures were directed at the human observers, as well as toward otherchimpanzees.