A husband-and-wife team at Georgia University's Language Research Centre, near Atlanta, reared a pygmy chimpanzee called Panbanisha who communicates in basic phrases using a computer keyboard. The research stems from work going back to 1970 when some chimpanzees were able to communicate with humans with varying degrees of competence.
Sue Savage-Rumbaugh and her husband Duane Rumbaugh say Panbanisha is the best language expert they have reared in their small community of research apes. The chimp was brought up learning to use a lexigram, a computer screen full of symbols which she can press to produce a rudimentary response to a human voice. She had an ordinary chimp as lifelong companion to compare the abilities of the two species. Professor Savage-Rumbaugh said: "The chimpanzees were spoken to and were responsive to the intonation, gestures, body language and general context of speech, but no attempts were made to explicitly foster the understanding of speech. The chimpanzees became able to recognise certain favourite or key words, such as `outdoors' or `M&Ms', when spoken in the proper context with the proper intonation."
But the level of recognition remained very simple and did not compare in any sense with an ability to understand complex human speech, she added.
Critics say this suggests the chimps do not understand true speech and syntax but simply identify known sounds. Several years ago a pygmy chimp called Kanzi could accurately locate the correct printed symbol on a lexigram for a given spoken word or phrase.
"This was truly unprecedented," said Professor Savage-Rumbaugh. "No ape, or indeed non-human of any sort, had been able to determine that a specific spoken word corresponded to either a picture or a printed symbol. Kanzi is the first ape to demonstrate real comprehension of spoken speech. The claim has been made for other apes, but comprehension in these apes has not been tested or demonstrated in controlled tests.".
Primatologists showed in June that wild chimpanzees are capable of passing on learned inventions and culture to their offspring. It might be possible for adult chimps with simple language abilities to teach their young to understand human speech. But apes can never learn to speak - their voice boxes are anatomically different to human ones.