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How To Teach an Ape To TalkCross-species communication 101.

By Daniel Engber
Updated Thursday, Feb. 24, 2005, at 7:26 PM ET
Koko and kitten

The woman who trained Koko the gorilla to use sign language has been accused of pressuring two former employees to expose themselves to the animal. According to the complaint, Francine Patterson (who also serves as Koko's interpreter) told the two employees that Koko had demanded to see their nipples. How do you train a great ape to communicate with you?

With hand signals, keyboards, or plastic tokens. Attempts to raise chimpanzees in human environments—and speak to them like humans—had failed to produce chimpanzee speech, so by the 1960s researchers were turning to other methods. The late '60s and '70s were the heyday of cross-species communication: Allen and Beatrix Gardner taught chimps to use American Sign Language, David Premack trained them with plastic tokens, and Duane Rumbaugh and Sue Savage-Rumbaugh got chimps and bonobos to use a special computer keyboard. Francine Patterson began training Koko the gorilla using ASL in 1972.

The Gardners began their research in 1966 with the goal of raising chimps as if they were human children. The animals lived in trailers designed for people, with television sets, kitchens, and toilets; they were expected to dress themselves, brush their teeth, do chores, and take on other human responsibilities. Whenever the chimps were awake, researchers would speak to them using signs—exactly as if they were deaf, human children.

Not long after the Gardners had put their first chimp in diapers, two researchers at Georgia State University—Rumbaugh and Savage-Rumbaugh—started using a keyboard to communicate with chimpanzees. Each key on the keyboard is marked with a shape that corresponds to a particular object or concept. The version they use today has hundreds of keys, which the animals punch in order to produce sentences. The computer provides treats, but only if the animal has constructed a sentence in the proper way. This keyboard language is called Yerkish, after the famous primatologist Robert Yerkes.

A similar approach used plastic tokens of different shapes and colors instead of keys. David Premack taught chimps to attach the metal-backed tokens to a magnetic slate to "write" sentences. He'd begin by teaching the animal basic associations between objects and tokens—she'd get an apple if she placed the "apple" piece on the slate. Then he'd train her to use and understand tokens that meant things like "color of" or "shape of." In the end, he could present the chimp with a series of tokens describing a new object. By looking at the tokens, she would know to choose an object that is "the color of chocolate" or "the shape of an apple."

Could any of these apes articulate ideas of their own? Most scientists believe that non-human primates can't learn anything beyond simple rules and associations. (Although, a few years ago, Koko did speak to her adoring fans via live Internet chat.) Today, not all talking animal research centers on primates: At Brandeis, for example, Irene Pepperberg has taught some linguistic basics to a gray parrot named Alex.

Next question?

Explainer thanks Allen Gardner of the University of Nevada, Deborah Fouts of Central Washington University, and David Premack.

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Daniel Engber is an associate editor at Slate. He can be reached at .
Photograph of Koko and kitten courtesy AP Photo/National Geographic Society, Ronald Cohn.
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