Chimps Talk with Their Hands

Righthanded gesturing in apes hints at the origins of human language The origins of language have long been a mystery, but mounting evidence hints that our unique linguistic abilities could have evolved from gestural communication in our ancestors. Such gesturing may also explain why most people are righthanded. Researchers at the Yerkes National Primate Research Center recently ex amined captive chimpanzees and found that most of them predominantly used their right hand when communicating with one another—for example, when greeting another chimp by extending an arm. The animals did not show this hand preference for noncommunicative actions, such as wiping their noses. Such lateralized hand use suggests that chimpanzees have a system in their left brain hemisphere that is coupled to the production of communicative gestures, says study author William Hopkins. The same cerebral hemisphere is host to most language functions in humans, which hints that an ancestral gestural system could have been the precursor for language, he says. That notion is supported by previous studies that have shown anatomical asymmetries in chimpanzees’ brains in areas that are considered to be ho mologues of human language centers, such as Broca’s area, Hopkins says. “Chimps that gesture with their right hand typically have a larger left Broca’s area, and those that don’t show a [hand] bias typically don’t show any asymmetry in the brain,” he notes. The idea that language emerged from an ancestral gestural system located in the left brain hemisphere could explain why the vast majority of people are righthanded, Hopkins says. If gesturing was strongly selected for in human evolution, then the fact that most people are righthanded is a consequence of that. This hypothesis challenges the longheld view that the opposite scenario is true: that righthandedness emerged for motor skills such as tool use and that communication built on the developed asymmetry in the motor system later.

Source of Information : Scientific American Mind March-April 2010