More recent experiments have shown that apes can learn to use, if not speak, true language (Fouts 1997; Miles 1983). Several apes have learned to converse with people through means other than speech. One such communication system is American Sign Language, or ASL, which is widely used by hearing-impaired Americans. ASL employs a limited number of basic gesture units that are analogous to sounds in
spoken language. These units combine to form words and larger units of meaning.
The first chimpanzee to learn ASL was Washoe, a female, who died in 2007 at the age of 42. Captured in West Africa. Washoe revolutionized the discussion of the language-learning abilities of apes (Carey 2007). The researchers always used ASL to communicate with each other in her presence. The chimp gradually acquired a vocabulary of more than 100 signs representing English words . At the age of two, Washoe began to combine as many as five signs into rudimentary sentences such as “you, me, go out, hurry.”
The second chimp to learn ASL was Lucy, Washoe’s junior by one year. Lucy died, or was murdered by poachers, in 1986, after having been introduced to “the wild” in Africa in 1979 (Carter 1988). Lucy used ASL to converse with her foster parents. After acquiring language, Washoe and Lucy exhibited several human traits: swearing, joking, telling lies, and trying to teach language to others (Fouts 1997).
When irritated, Washoe called her monkey neighbors at the institute “dirty monkeys.” Lucy insulted her “dirty cat.” On arrival at Lucy’s place, Fouts once found a pile of excrement on the floor. When he asked the chimp what it was, she replied, “dirty, dirty,” her expression for feces. Asked whose “dirty, dirty” it was, Lucy named Fouts’s coworker, Sue. When Fouts refused to believe her about Sue, the chimp blamed the excrement on Fouts himself.
Cultural transmission of a communication system through learning is a fundamental attribute of language. Washoe, Lucy, and other chimps have tried to teach ASL to other animals, including their own offspring. Washoe taught gestures to other institute chimps, including her son Sequoia, who died in infancy (Fouts, Fouts, and Van Cantfort 1989).
Psychologist Penny Patterson’s work with gorillas at Stanford University seems more daring than the chimp experiments. Patterson raised her now full-grown female gorilla, Koko, in a trailer next to a Stanford museum. Koko’s vocabulary surpasses that of any chimp. She regularly employs 400 ASL signs and has used about 700 at least once.
Koko and the chimps also show that apes share still another linguistic ability with humans: productivity. Speakers routinely use the rules of their language to produce entirely new expressions that are comprehensible to other native speakers. I can, for example, create “baboonlet” to refer to a baboon infant. I do this by analogy with English words in which the suffix -let designates the young of a species. Anyone who speaks English immediately understands the meaning of my new word. Koko, Washoe,
Lucy, and others have shown that apes also are able to use language productively. Lucy used gestures she already knew to create “drinkfruit” for watermelon. Washoe, seeing a swan for the first time, coined “waterbird.” Koko, who knew the gestures for “finger” and “bracelet,” formed “finger bracelet” when she was given a ring.
Apes also have demonstrated linguistic displacement. Absent in call systems, this is a key ingredient in language. Normally, each call is tied to an environmental stimulus such as food. Calls are uttered only when that stimulus is present. Displacement means that humans can talk about things that are not present. We don’t have to see the objects before we say the words. Human conversations are not limited by place. We can discuss the past and future, share our experiences with others, and benefit from theirs. Patterson has described several examples of Koko’s capacity for displacement (Patterson 1978). The gorilla once expressed sorrow about having bitten Penny three days earlier. Koko has used the sign “later” to postpone doing things she doesn’t want to do.
Certain scholars doubt the linguistic abilities of chimps and gorillas . These people contend that Koko and the chimps are comparable to trained circus animals and don’t really have linguistic ability.
No one denies the huge difference between human language and gorilla signs. There is a major gap between the ability to write a book or say a prayer and the few hundred gestures employed by a well-trained chimp. Apes aren’t people, but they aren’t just animals either. Let Koko express it: When asked by a reporter whether she was a person or an animal, Koko chose neither. Instead, she signed “fine animal
gorilla” (Patterson 1978)
Chimps and gorillas have a rudimentary capacity for language. They may never have invented a meaningful gesture system in the wild. However, given such a system, they show many humanlike abilities in learning and using it. Of course, language use by apes is a product of human intervention and teaching. The experiments mentioned here do not suggest that apes can invent language (nor are human children ever faced with that task). However, young apes have managed to learn the basics of gestural
language. They can employ it productively and creatively, although not with the sophistication of human ASL users.
Table 4.1 summarizes the contrasts between language, whether sign or spoken, and call systems.
Language Contrasted with Call Systems
| Human Language | Primate Call Systems |
| Has the capacity to speak of things and events that are not present (displacement). | Are stimuli-dependent; the food call will be made only in the presence of food; it cannot be faked. |
| Has the capacity to generate new expressions by combining other expressions (productivity). | Consist of a limited number of calls that cannot be combined to produce new calls. |
| Is group specific in that all humans have the capacity for language, but each linguistic community has its own language, which is culturally transmitted. | Tend to be species specific, with little variation among communities of the same species for each call. |