Baby Apes’ Arm Waving Hints At Origins Of Language
Actions speak louder than words. Baby chimps, bonobos, gorillas and orang-utans – our four closest living relatives – quickly learn to use visual gestures to get their message across, providing the latest evidence that hand waving may have been a vital first step in the development of human language.
After a long search for the origins of language in animal vocalisations, some evolutionary biologists have begun to change tack. The emerging “gesture theory” of language evolution has it that our ancestors’ linguistic abilities may have begun with their hands rather than their vocal cords.
Katja Liebal and colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have found new evidence for the theory by studying how communication develops in our closest living relatives. They discovered that all four great apes – chimps, bonobos, gorillas and orang-utans – develop a complex repertoire of gestures during the first 20 months of life.
Those gestures included the tactile pokes and nudges that are expected to effectively capture another’s attention in any situation, but they also included visual gestures such as extending the arms towards another ape or head shaking. To be effective communication tools, these visual gestures require that a young ape be aware that another individual is paying attention before using them, if they want to get their message across.
“Given that purely visual gestures require more advanced social cognition we would have expected them to appear later in the apes’ lives,” says Liebal. “Their early presence in all four species is really surprising.” Human babies also quickly learn to use visual gestures. Liebal’s team argues that this puts great apes and humans on a different evolutionary branch from monkeys, which typically do not learn to use visual gestures until later in life.
Michael Corballis at the University of Auckland, New Zealand, agrees. “In monkeys, intentional arm movements are dedicated mainly to grasping,” he says. “Communicative gestures probably emerged in apes, and began to assume grammatical forms in hominins.”
Shadows of the differences that emerged in hominins can still be seen by comparing the type of visual gestures used by young great apes with those that young children use. “The apes did not use a single gesture systematically, either within a species or across all species – that’s in striking contrast to human infants,” says Ulf Liszkowski at the Max Planck Institute for Psycholinguistics in Nijmegen in the Netherlands.
Liszkowski has just completed a study of gesture use by young children in seven different cultural settings, including Indonesia, Japan, Mexico and Peru. In all cases children had learned to point with their index finger by 14 months (Cognitive Science, in press). “Interestingly, it is exactly that index-finger-pointing gesture which did not emerge naturally in any of the ape species in the Liebal study,” he says.
Beyond these broad patterns, however, Corballis says it is unlikely that the great ape study will ultimately lead to an evolutionary tree of gestures that reveals exactly how language appeared in humans. “I suspect apes have evolved their own idiosyncratic gestures since they diverged from hominins,” he says.
From NewScientist.com
