Chimps May Reveal the Origins of Language
Posted by Science Oxford on November 27, 2009 | comments
New research suggests that our left-brain dominance for language comes from our ape-like ancestors.
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Visit this page »Chimps seem to use the left half of the brain when communicating with gestures—just as humans do when using language, researchers have found.
The findings, in a species considered one of the two closest relatives of humans in the animal kingdom, suggest that our left-brain dominance for language comes from our ape-like ancestors, the scientists said. The results also support a theory that spoken language evolved from gestural communication, they added.
Most human linguistic functions are controlled by the left hemisphere, or half, of the brain. The study of captive chimpanzees at the Yerkes National Primate Research Center in Atlanta, Ga. found that a large majority of the chimps showed a “significant” bias towards right-handed gestures, the investigators said. In general, the right half of the body is controlled by the left half of the brain.
The study is reported in the January issue of the research journal Cortex.
The scientists, supervised by William D. Hopkins of Agnes Scott College in Georgia, studied hand use in 70 captive chimpanzees over a period of 10 months, recording a variety of communicative gestures specific to chimps.
These included actions classified as “arm threat,” “extend arm” or “hand-slap,” produced in different social contexts, such as attention-getting, shared excitation, threat, aggression, greeting, reconciliation or invitations for grooming or play. The gestures were directed both at other chimps and at human observers.
“The degree of predominance of the right hand for gestures is one of the most pronounced we have ever found in chimpanzees in comparison to other non-communicative manual actions. We already found such manual biases in this species for pointing gestures exclusively directed to humans. These additional data clearly showed that right-handedness for gestures is not specifically associated to interactions with humans,” Hopkins said.
Co-authors Adrien Meguerditchian and Jacques Vauclair of Aix-Marseille University in France said the findings offer “additional support” to the idea that speech evolved initially from a gestural communicative system in our ancestors. Apes’ gestural communication shares some key features with human language, such as intentionality, referential properties and flexibility of learning and use, they argued.
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