A BONOBO has surprised his trainers by appearing to make up his own 鈥渨ords鈥�. It鈥檚 the first report of an ape making sounds that seem to hold their meaning across different situations, and the latest challenge to the orthodox view that animals don鈥檛 have language.
Kanzi is an adult bonobo, or pygmy chimp, kept at Georgia State University in Atlanta. He has grown up among humans, and is adept at communicating with symbols. He understands some spoken English, and can respond to phrases such as 鈥済o out of the cage鈥� and 鈥渄o you want a banana?鈥� Jared Taglialatela and Sue Savage-Rumbaugh, who work with Kanzi, noticed that he was making gentle noises during his interactions with them. 鈥淲e wanted to know if there was any rhyme or reason to when they were produced,鈥� says Taglialatela.
So his team studied 100 hours of videotape showing Kanzi鈥檚 day-to-day interactions and analysed the sounds he made at various times. They picked situations in which the bonobo鈥檚 actions were unambiguous: for example, while he was eating a banana, pointing to the symbol for 鈥済rapes鈥�, or responding to a request to go outside by leaving the cage.
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They identified four sounds Kanzi made in different contexts: banana, grapes, juice and yes. In each context, Kanzi made the same sound. 鈥淲e haven鈥檛 taught him this,鈥� says Taglialatela. 鈥淗e鈥檚 doing it on his own.鈥�
Some will argue that the sounds are simply the result of differences in Kanzi鈥檚 emotional state. Taglialatela concedes that emotions may play a part, but says they are not the whole story. For instance, Kanzi鈥檚 sound for 鈥測es鈥� stayed the same across very different emotional states.
Primatologist Frans de Waal of Emory University in Atlanta, Georgia, agrees. 鈥淭hat emotion is involved doesn鈥檛 rule out that he鈥檚 following rules that have some sort of cognitive component.鈥�
Kanzi is just the latest primate to challenge the view that animals have no language ability. Language used to be popularly defined as symbolic communication until Washoe, a chimpanzee, stumped everyone by learning to communicate in American Sign Language. 鈥淭he linguists then came up with a definition that emphasised syntax much more than symbols,鈥� says de Waal. 鈥淪ometimes we feel it鈥檚 a bit unfair that they move the goalposts as soon as we get near.鈥�
Recently researchers studying Campbell鈥檚 and Diana monkeys in the Ivory Coast in West Africa found some evidence of syntax in the calls the monkeys made (快猫短视频, 30 March 2002, p 10). And Karen Hallberg and Sally Boysen of Ohio State University, Columbus, have noticed hints that when chimps see food, they make calls that specify its desirability as high, medium or low, and that other chimps can interpret the sounds.
But Kanzi comes closest yet to providing concrete evidence that apes can make sounds that carry a particular meaning. 鈥淜anzi is modifying his sounds to denote certain things in his environment,鈥� says de Waal. 鈥淭hat鈥檚 very special.鈥�
The results are significant and exciting, agrees primatologist John Mitani of the University of Michigan in Ann Arbor. 鈥淒espite the fact that we have had glimmerings of this in the monkey world, few instances of anything like this have been documented among our closest living relatives, chimps and bonobos,鈥� he says.
Taglialatela and his team have now started studying seven more bonobos in their lab, some of which have not been language-trained. They are also analysing Kanzi鈥檚 sounds to see if he is actually trying to imitate human speech. Until more results are in, Mitani and de Waal caution against drawing any firm conclusions. For Kanzi鈥檚 ability to be considered similar to language, it must be flexible and applicable to many different situations, they say. And Hallberg says she won鈥檛 consider Kanzi鈥檚 sounds to be communication until other bonobos are shown to respond to them appropriately.
Nevertheless, the observations add to the growing body of evidence that language skills did not just show up suddenly in humans, and hint that non-human primates may have abilities that could be described as primitive language. 鈥淭here have to be evolutionary precursors to what we do,鈥� says Mitani. 鈥淲e are beginning to find them in the primate world.鈥�