Language is a collection of symbols that represents objects, actions, and thoughts. It is representational, allowing for the transmission and relocation of information between minds. It can be written, spoken, gestured, and/or signed for purposes of communication.
It is often debated whether or not humans are the only animal possessing language capabilities. In particular, some studies have revealed that great apes (chimpanzees, bonobos, gorillas, and orangutans) exhibit some language like qualities. Apes have a larger brain size to body size ratio than all other nonhuman primates. In addition, one of the apes, the chimpanzee (Pan troglodytes), shares 98.4% of their deoxyribonucleic acid (DNA) with humans.
Apes typically use scent markings, pilo (hair) erection, facial expressions, and vocalizations, as well as other verbal and visual means of communication. Apes also can communicate with humans, and chimpanzees are capable of forming infrequent human vocalizations in response to human speech. In addition, some apes make the complex hand movements used in American Sign Language (ASL).
Nonetheless, ape language is qualitatively different than human language. Apes do not have a vocal tract that allows them to speak the same way people do. Also, apes do not have the same level of intelligence as humans, which some believe is necessary for understanding and producing speech. Furthermore, ape language is not as complex or expressive as human language.
There have been many studies on the language abilities of the great apes. Research has been conducted on the evolution of language, the acquisition and production of language, as well as strategies for teaching language to humans. The results of some ape language studies have been beneficial to those working on language acquisition in mentally challenged children.
Manual signing, plastic “words,” computer lexigrams, and simultaneous communication have been used in ape language studies. In fact, human curiosity with the language abilities of apes dates back to the 1930s. In 1933, Winthrop and Luella Kellogg raised Gua, a female chimpanzee, along with their infant son, Donald. Over a period of 9 months, Gua was able to understand and respond to about 70 verbal commands. In 1966, another chimpanzee, Sarah, participated in language research designed by David Premack. Sarah learned to form sentences by placing plastic tokens that symbolized words in a vertical line. Sarah was able to read and write with over 130 words.
In 1967, two psychologists, Beatrice and Allen Gardner, taught Washoe, an infant female chimpanzee, how to use ASL in the same way that parents teach deaf children to sign. After a period of about 3 years, Washoe learned to sign approximately 130 words. Lana, another female chimpanzee, participated in a language study beginning in 1971 at the Regional Centre of Primate Studies at Yerkes. Duane Rumbaugh and colleagues placed Lana in an experimental chamber, where she used a computer lexigram language system to “talk.”
Beginning in 1972, Koko, a female gorilla (Gorilla gorilla), learned ASL through simultaneous communication with Penny Patterson. Koko responded to verbal questions and signed novel combinations of words. Researchers noted that at times, Koko even talked (signed) to herself and her dolls.
Nim Chimpsky, a chimpanzee, was raised and taught sign language as if he were human. In 1979, Herbert Terrace developed a language study at Columbia University in which Nim was a subject. In 44 months of training, Nim learned 125 words and was able to combine two- and three-word utterances. However, after reviewing years of data, Terrace concluded that most of the time Nim was not signing spontaneously. Rather, he appeared to be imitating his trainer’s signs.
Chantek, an orangutan (Pongo pygmaeus), was taught ASL by Lyn Miles, who raised him as her child. As Chantek’s vocabulary increased, the ideas that he expressed became more intricate. Chantek used signs in combinations and even invented his own signs (for example, “eye-drink” for contact lens solution). Chantek learned over 150 words from 1979 to 1986 and did not simply imitate his caregivers, but used signs to initiate communication. In addition, Chantek was able to comprehend spoken English.
Kanzi, a bonobo (Pan paniscus), learned to use language without specifically being trained or prompted to do so. Kanzi accompanied his mother, Matata, when she attended language-learning sessions in 1980 with Sue Savage-Rumbaugh. At the time, Matata was being taught a computer lexigram language. During Matata’s language training, Kanzi often tried to interact with the researchers and sometimes touched the lexigrams on the keyboard. At first, Kanzi received little attention because his mother was the focus of the study. However, one day, Matata was absent and Kanzi used the lexigrams competently, to the amazement of the researchers. To date, Kanzi has learned approx-imately 256 lexigram words and can understand 500 spoken English words.
In 1985, Kanzi’s sister, Panbanisha, joined the language studies at the Language Research Center in Georgia. Panbanisha, a bonobo or “pygmy” chimpanzee, was co-reared with Panzee, a “common” chimpanzee, to see if there were any differences in language acquisition and production between the two species of chimps. Like Kanzi, Panbanisha and Panzee became linguistically competent without specific training. However, it was found that there were differences in the learning abilities of the two apes. Panbanisha learned symbols sooner and combined words in more novel ways than Panzee. Currently, Panbanisha understands over 3,000 words and uses a vocabulary of 250 words.
Although much has been learned from ape language studies regarding the ontogeny of language, there still is a substantial amount of controversy regarding how much apes’ language abilities resemble that of humans. Some research shows that apes do not use language spontaneously (for example, Nim), while other research demonstrates that they do (Chantek). Another point of contention is whether or not apes can form grammatically ordered sentences. Although apes do construct sentences using multiple signs, the sentences are often random and/or repetitious. Notwithstanding, Kanzi does not repeat himself often and appears to understand the grammatical rules about lexigram order.
After Terrace’s conclusions that Nim Chimpsky seemed to be mimicking the signs of his trainers and could not grasp syntax, funding for ape language research dwindled. Terrace’s findings were a major disappointment to talking-ape enthusiasts. However, the work of Sue Savage-Rumbaugh and colleagues brings an encouraging perspective to those who believe that great apes can acquire and produce language.
- Fouts, R., & Mills, S. T. (1998). Next of kin: My conversations with chimpanzees. New York: Perennial Currents.
- Greenspan, S. I., & Shanker, S. G. (2004). The first idea: How symbols, language, and intelligence evolved from our primate ancestors to modern humans. New York: Da Capo Press.
- King, B. (1999). The origins of language. Santa Fe, NM: School of American Research Press.
- Patterson, F., & Cohn, R. H. (1988). Koko’s story. New York: Scholastic.
- Premack, D. (1976). Intelligence in ape and man. Hillsdale, NJ: Lawrence Erlbaum.
- Savage-Rumbaugh, S., Shanker, S. G., & Taylor, T. J. (2001). Apes, language, and the human mind. Oxford: Oxford University Press.
- Terrace, H. S. (1987). Nim, a chimpanzee who learned sign language. New York: Columbia University Press