APA Research Paper (Shaw)

 

Apes and Language:

A Review of the Literature

Over the past 30 years, researchers have demonstrated that

the great apes (chimpanzees, gorillas, and orangutans) resemble

humans in language abilities more than had been thought possible.

Just how far that resemblance extends, however, has been a

matter of some controversy. Researchers agree that the apes have

acquired fairly large vocabularies in American Sign Language and

in artificial languages, but they have drawn quite different conclusions

in addressing the following questions:

1. How spontaneously have apes used language?

2. How creatively have apes used language?

3. Can apes create sentences?

4. What are the implications of the ape language studies?

This review of the literature on apes and language focuses on

these four questions.

How Spontaneously Have

Apes Used Language?

In an influential article, Terrace, Petitto, Sanders, and Bever

(1979) argued that the apes in language experiments were not

using language spontaneously but were merely imitating their

trainers, responding to conscious or unconscious cues. Terrace and

his colleagues at Columbia University had trained a chimpanzee,

Nim, in American Sign Language, so their skepticism about the

apes’ abilities received much attention. In fact, funding for ape

language research was sharply reduced following publication of

their 1979 article “Can an Ape Create a Sentence?”

In retrospect, the conclusions of Terrace et al. seem to have

been premature. Although some early ape language studies had

not been rigorously controlled to eliminate cuing, even as early

as the 1970s R. A. Gardner and B. T. Gardner were conducting

double-blind experiments that prevented any possibility of cuing

(Fouts, 1997, p. 99). Since 1979, researchers have diligently

guarded against cuing.

Perhaps the best evidence that apes are not merely

responding to cues is that they have signed to one another

spontaneously, without trainers present. Like many of the apes

studied, gorillas Koko and Michael have been observed signing

to one another (Patterson & Linden, 1981). At Central Washington

University the baby chimpanzee Loulis, placed in the

care of the signing chimpanzee Washoe, mastered nearly fifty

signs in American Sign Language without help from humans.

“Interestingly,” wrote researcher Fouts (1997), “Loulis did not

pick up any of the seven signs that we [humans] used around

him. He learned only from Washoe and [another chimp] Ally”

(p. 244).

The extent to which chimpanzees spontaneously use language

may depend on their training. Terrace trained Nim using the

behaviorist technique of operant conditioning, so it is not surprising

that many of Nim’s signs were cued. Many other researchers

have used a conversational approach that parallels the process by

which human children acquire language. In an experimental study,

O’Sullivan and Yeager (1989) contrasted the two techniques, using

Terrace’s Nim as their subject. They found that Nim’s use of

language was significantly more spontaneous under conversational

conditions.

How Creatively Have

Apes Used Language?

There is considerable evidence that apes have invented

creative names. One of the earliest and most controversial examples

involved the Gardners’ chimpanzee Washoe. Washoe, who knew

signs for “water” and “bird,” once signed “water bird” when in the

presence of a swan. Terrace et al. (1979) suggested that there was

“no basis for concluding that Washoe was characterizing the swan

as a ‘bird that inhabits water.’” Washoe may simply have been

“identifying correctly a body of water and a bird, in that order”

(p. 895).

Other examples are not so easily explained away. The

bonobo Kanzi has requested particular films by combining symbols

on a computer in a creative way. For instance, to ask for Quest for

Fire, a film about early primates discovering fire, Kanzi began to

use symbols for “campfire” and “TV” (Eckholm, 1985). The gorilla

Koko, who learned American Sign Language, has a long list of

creative names to her credit: “elephant baby” to describe a Pinocchio

doll, “finger bracelet” to describe a ring, “bottle match” to

describe a cigarette lighter, and so on (Patterson & Linden, 1981,

p. 146). If Terrace’s analysis of the “water bird” example is applied

to the examples just mentioned, it does not hold. Surely

Koko did not first see an elephant and then a baby before signing

“elephant baby”--or a bottle and a match before signing “bottle

match.”

Can Apes Create Sentences?

The early ape language studies offered little proof that apes

could combine symbols into grammatically ordered sentences. Apes

strung together various signs, but the sequences were often random

and repetitious. Nim’s series of sixteen signs is a case in point:

“give orange me give eat orange me eat orange give me eat orange

give me you” (Terrace et al., 1979, p. 895).

More recent studies with bonobos at the Language Research

Center in Atlanta have broken new ground. Kanzi, a bonobo trained

by Savage-Rumbaugh, seems to understand simple grammatical

rules about word order. For instance, Kanzi learned that in twoword

utterances action precedes object, an ordering also used by

human children at the two-word stage. In a major article reporting

on their research, Greenfield and Savage-Rumbaugh (1990) wrote

that Kanzi rarely “repeated himself or formed combinations that

were semantically unrelated” (p. 556).

More important, Kanzi began on his own to create certain

patterns that may not exist in English but can be found among

deaf children and in other human languages. For example, Kanzi

used his own rules when combining action symbols. Symbols

that involved an invitation to play, such as “chase,” would

appear first; symbols that indicated what was to be done during

play (“hide”) would appear second. Kanzi also created his own

rules when combining gestures and symbols. He would use

the symbol first and then gesture, a practice often followed by

young deaf children (Greenfield & Savage-Rumbaugh, 1990,

p. 560).

In a later study, Kanzi’s abilities to understand spoken

language were shown to be similar to those of a 2-1/2-year-old

human, Alia. Rumbaugh (1995) reported that “Kanzi’s comprehension

of over 600 novel sentences of request was very comparable

to Alia’s; both complied with the requests without assistance on

approximately 70% of the sentences” (p. 722). A recent monograph

provided examples of the kinds of sentences both Kanzi and

Alia were able to understand:

For example, the word ball occurred in 76 different sentences,

including such different requests as “Put the leaves in your

ball,” “Show me the ball that’s on TV,” “Vacuum your ball,” and

“Go do ball slapping with Liz.” Overall, 144 different content

words, many of which were presented in ways that required syntactic

parsing for a proper response (such as “Knife your ball”

vs. “Put the knife in the hat”), were utilized in the study.

(Savage-Rumbaugh et al., 2000, pp. 101-102)

The researchers concluded that neither Kanzi nor Alia could have

demonstrated understanding of such requests without comprehending

syntactical relationships among the words in a sentence.

What Are the Implications of the

Ape Language Studies?

Kanzi’s linguistic abilities are so impressive that they may

help us understand how humans came to acquire language. Pointing

out that 99% of our genetic material is held in common with

the chimpanzees, Greenfield and Savage-Rumbaugh (1990) have

suggested that something of the “evolutionary root of human language”

can be found in the “linguistic abilities of the great apes”

(p. 540). Noting that apes’ brains are similar to those of our

human ancestors, Leakey and Lewin (1992) argued that in ape

brains “the cognitive foundations on which human language could

be built are already present” (p. 244).

The suggestion that there is a continuity in the linguistic

abilities of apes and humans has created much controversy.

Linguist Noam Chomsky has strongly asserted that language is

a unique human characteristic (Booth, 1990). Terrace has continued

to be skeptical of the claims made for the apes, as have

Petitto and Bever, coauthors of the 1979 article that caused such

skepticism earlier (Gibbons, 1991).

Recently, neurobiologists have made discoveries that may

cause even the skeptics to take notice. Ongoing studies at the

Yerkes Primate Research Center have revealed remarkable similarities

in the brains of chimpanzees and humans. Through brain scans

of live chimpanzees, researchers have found that, as with humans,

“the language-controlling PT [planum temporale] is larger on the

left side of the chimps’ brain than on the right. But it is not lateralized

in monkeys, which are less closely related to humans than

apes are” (Begley, 1998, p. 57).

Although the ape language studies continue to generate

controversy, researchers have shown over the past 30 years that

the gap between the linguistic abilities of apes and humans is far

less dramatic than was once believed.

References

Begley, S. (1998, January 19). Aping language. Newsweek, 131,

56-58.

Booth, W. (1990, October 29). Monkeying with language: Is chimp

using words or merely aping handlers? The Washington Post, p.

A3.

Eckholm, E. (1985, June 25). Kanzi the chimp: A life in science.

The New York Times, pp. C1, C3.

Fouts, R. (1997). Next of kin: What chimpanzees have taught me

about who we are. New York: William Morrow.

Gibbons, A. (1991). Déjà vu all over again: Chimp-language wars.

Science, 251, 1561-1562.

Greenfield, P. M., & Savage-Rumbaugh, E. S. (1990). Grammatical

combination in Pan paniscus: Processes of learning and invention

in the evolution and development of language.

In S. T. Parker & K. R. Gibson (Eds.), “Language” and intelligence

in monkeys and apes: Comparative developmental perspectives

(pp. 540-578). Cambridge: Cambridge University

Press.

Leakey, R., & Lewin, R. (1992). Origins reconsidered: In search of

what makes us human. New York: Doubleday.

O’Sullivan, C., & Yeager, C. P. (1989). Communicative context and

linguistic competence: The effect of social setting on

a chimpanzee’s conversational skill. In R. A. Gardner, B. T.

Gardner, & T. E. Van Cantfort (Eds.), Teaching sign language to

chimpanzees (pp. 269-279). Albany: SUNY Press.

Patterson, F., & Linden, E. (1981). The education of Koko.

New York: Holt, Rinehart & Winston.

Rumbaugh, D. (1995). Primate language and cognition:

Common ground. Social Research, 62, 711-730.

Savage-Rumbaugh, E. S., Murphy, J. S., Sevcik, R. A., Brakke,

K. E., Williams, S. L., Rumbaugh, D. M., et al. (2000). Language

comprehension in ape and child: Monograph. Atlanta, GA:

Language Research Center. Retrieved January 6, 2000, from the

Language Research Center Web site: http://

www.gsu.edu/~wwwlrc/monograph.html

Terrace, H. S., Petitto, L. A., Sanders, R. J., & Bever, T. G. (1979).

Can an ape create a sentence? Science, 206,

891-902.


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