Shadows of Forgotten Ancestors

One of the most thoroughgoing examinations of the linguistic and grammatical abilities of apes was done by the psychologist Herbert Terrace and his colleagues, who recorded on videotape nearly twenty thousand signing attempts generated by a male chimp named Nim.²⁰ He mastered over one hundred different gestural signs. Nim would regularly sign “Play me” or “Nim eat” in context and with apparent understanding. But there was no evidence, Terrace concluded, that Nim put more than two signs together in any consistent manner appropriate to the context. The average length of his sentences was less than two words long. His longest recorded sentence was “Give orange me give eat orange me eat orange give me eat orange give me you.” It does seem a little frantic, but oranges are tasty, chimps are not known for their patience, and anyone who has spent time with a small excited child will recognize the syntax. Note that four of the words are non-redundant (“give me orange you”), and that no words irrelevant to this urgent request are included among the sixteen. Emphasis through repetition is common in human languages. But the simplicity of chimp sentences has rendered their use of language unimpressive in the minds of many psychologists and linguists. Nim was also belittled for interrupting his trainers’ signing with his own, for being too imitative (repeating remarks of his trainer), and for not inventing grammatical rules such as the subject-predicate sequence.

This work has in turn been criticized. Chimps require close emotional ties for social tasks and, one would think, especially for something as difficult as language; instead, Nim had sixty different trainers over a four-year period. There is a tension between a loving, one-on-one environment that might be needed to teach language skills and the emotionally sterile protocols needed so that scientific results are, with high reliability, uncontaminated by the enthusiasm of the experimenters. It has frequently been found that apes sign most creatively in spontaneous circumstances in their everyday life, and not in experimental sessions. Too, there was great emphasis on drill in the Nim experiments, the very opposite of spontaneity. The complaint about Nim interrupting the signing of his trainer has itself been belittled, because Ameslan speakers may sign simultaneously without stepping on each other’s lines, an advantage of signing over speech. Delayed imitation is just what human children do when they first learn language. For all these reasons, just how much grammatical dexterity apes have is still an open question.²¹

But clearly chimps can use something like the rudiments of language with much greater facility than had been thought possible before the experiments of the Gardners. They can unambiguously associate certain signs with certain people, animals, or objects—unsurprising when there are monkeys

with different alarm cries and evasion strategies for different species of predators. Chimps have mastered an elementary vocabulary of a few hundred words, comparable to what a normal human two-year-old can do. Chimps who have some knowledge of these signs and who are raised together have been known spontaneously to sign to one another. There is at least one case in which a young chimp, uninstructed by any human, is said to have learned dozens of signs from another chimp knowledgeable in Ameslan.²²

“We may consider it proven,” said the psychologist William James, “that the most elementary single difference between the human mind and that of brutes lies in this deficiency on the brute’s part to associate ideas by similarity.” He held this to be a more fundamental cause of human uniqueness than reason, language, and laughter—all of which, he taught, emerge from recognizing similarities among ideas.²³

Some chimps were taught a common symbol to describe any one of three foods, and another to describe any one of three tools. Then they were taught the individual names of other foods and other tools and asked to put them in the proper categories—not the new foodstuffs or tools themselves, but the arbitrary names

of the new foodstuffs and tools. They did exceptionally well.²⁴ How is this possible, unless chimps reason, form abstract ideas, and “associate ideas by similarity”? Another domesticated chimp, Viki Hayes, was given two piles of pictures, one of humans, the other of nonhumans, and then handed a stack of additional pictures and invited to categorize. Her performance was perfect, with one small exception: She placed the picture of herself among the humans.