Can chimpanzees learn human language?

Chimpanzee Communication

Dr. Roger Fouts tries to teach American Sign Language to a chimp named Lucy in 1972.
Dr. Roger Fouts tries to teach American Sign Language to a chimp named Lucy in 1972.
Nina Leen/Time & Life Pictures/Getty Images

A female chimpanzee named Washoe kicked off man's earnest quest to teach chimps human language. She was born in Africa in 1965 and eventually taken to Washoe County, Nev. (her namesake); that's where Washoe became the subject of cognitive research performed by Allen and Beatrix Gardener. The chimp wowed the world when she successfully learned American Sign Language, which had never happened before with a nonhuman primate. Washoe then passed her skills on to her adopted son Loulis, and by the time she died in 2007, Washoe had mastered around 130 signs [source: Carey].

In 1973, Columbia University psychologist Herbert Terrace wanted to see what happened with a chimp's language if it were raised as a human [source: Adler]. Nim Chimpsky -- named in snide homage for Noam Chomsky -- moved in with a family in New York City and was taught American Sign Language. Although Nim memorized 150 signs, researchers discovered his proficiency sprang from imitation of his teacher rather than unprompted communication [source: Adler]. Like Washoe, Nim hadn't cracked the code on spontaneous, humanlike communication.

Nevertheless, there are some interesting things going on in the apes' brains when signing or communicating with their innate gestures and vocalizations. PET scans conducted during a study for the Yerkes National Primate Research Center at Emory University found that chimpanzee communication activated the same regions of the brain as human language, particularly Broca's area and Wernicke's area [source: Moskowitz].

That breakthrough likely came as little surprise to lead primatologist for the Great Ape Trust, Susan Savage-Rumbaugh. Savage-Rumbaugh firmly believes that apes are capable of linguistic communication with humans and points to Kanzi and Panbanisha -- bonobo pygmy chimps she has worked with for more than 20 years -- as evidence. Instead of relying solely on sign language, Savage-Rumbaugh created lexigrams, or symbolic word representations, to teach the bonobos. She has also strived to meld the chimpanzee and human lifestyles to give the apes context for the words they're learning.

The result? Kanzi knows an impressive 360 lexigrams. Using a specialized series of keyboards with a lexigram on each key, Kanzi can point to a symbol to "say" a word. Panbanisha knows even more lexigrams. Savage-Rumbaugh also cites instances of creativity and word play in the bonobos, demonstrating that they are not simply memorizing words. For instance, Panbanisha pointed to the lexigram for "monster" in response to a poorly behaved visitor [source: Hamilton]. They also seem to understand syntax when tested. If Savage-Rumbuagh asks Kanzi to put raisins in a cup of water, the bonobo understands the difference between that and if she were to ask him to pour water on top of the raisins [source: Begley].

Even with those skills, Kanzi and Panbanisha's language abilities match up to that of a toddler [source: Cohen]. And the lack of spontaneous, noninstigated communication lingers. Scientists at the Yerkes National Primate Research Center may have pinpointed the key to that chimpanzee language gap in spring 2008.

Using Diffusion Tensor Imaging that traces neural paths, the researchers compared the brains of humans, rhesus monkeys and chimpanzees. Zeroing in on the arcuate fasciculus, the bundle of nerves that connects the brain's language centers, the imaging showed more widespread nerve connections spanning across the mid-temporal region in humans [source: Moskowitz]. Those expanded connections imply a greater ability of humans to analyze and contextualize linguistic information and could be the key difference between how we communicate versus chimps.

But as long as Kanzi and others continue to baffle us with their recognition and use of humanlike communication, the case of chimpanzees mastering our language is far from closed.

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