To What Extent Can Apes Communicate Through the Use of Sign Language?

To what extent can apes communicate through the use of sign language?

Apes use a variety of communication techniques with each other in the wild, but in captivity, some have been trained to use American Sign Language. Knowing signs gives the possibility of understanding the needs, wants, and dislikes of the ape. It is possible that apes can communicate effectively through the use of sign language and it has been observed in several cases.

In the wild, apes have different ways of visual communication such as hair erection, their general posture, and the use of different facial expressions.

American Sign Language is a visual language in that it also uses facial expressions as a part of the vocabulary; for example, two different signs can be the same in movement and location but use different facial expressions to convey the meaning. Apes cannot speak like humans because “apes’ vocal cords (or some other part of their anatomy) are not built for speaking” (De Luce).

Apes may not have the necessary mental and physical equipment, but they still have ways of communicating with each other. “Additional studies indicate that the production of sign language is controlled by the same brain areas as speech” (Hopkins). Therefore, it is possible that apes can use speech through the use of sign language.

Some chimpanzees that have been raised by humans have been taught how to use sign language. At the Chimpanzee and Human Communication Institute (CHCI) at Central Washington University, several chimpanzees know and use sign language with their trainers and each other.

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These chimpanzees use signs as single words as well as a certain combination with other signs. “Requests for objects and actions were the predominant communicative intentions of the sign utterances, though naming and answering also occurred” (Rivas). This is the same way humans first learn to communicate, by explaining something is wanted.

Washoe was a female chimpanzee that was raised by her caretakers and taught sign language before entering CHCI. She knew to sign the word “more” when she wanted to be tickled more or eat more. She knew the meanings of signs and made connections with others, “Washoe has transferred the DOG sign to the sound of barking by an unseen dog” (Gardner). What makes a sign reliable is when three separate observers have recorded its use over 15 consecutive days. Washoe knew 240 different reliable signs and mainly used them for the use of teaching her young and expressing her concern for them.

The use of sign language has also been seen in chimpanzees signing to each other. Washoe adopted a male infant chimpanzee, Loulis, and without the aid of any human teaching sign language to him for the first five years of his life, he learned 50 different signs on his own by observing the other chimpanzees. Sign language must have been beneficial to learning to communicate with the other chimpanzees, otherwise, Loulis most likely would not have bothered learning it. Similar to how human children learn the language, Loulis learned by observing others and with the help of Washoe to mold his hands correctly for signing words. Humans can learn sign language before the ability to speak because it is a visual language so it is not far off to assume apes can have a similar brain function of understanding what signing is and the meaning behind it.

Koko is a female gorilla that learned American Sign Language at the age of one year old. Koko has learned over 1000 signs and can understand at least 2000 signs as well as invent word sign combinations. She has been caught numerous times signing to herself alone and in the terror, which shows a level of self-awareness. Sign language also has allowed her to openly express her emotions; for example, when she was told her pet cat had died she would sign “cry” repeatedly. “A great deal of creativity, spontaneity, and structure characterize her utterances” (Patterson). When Koko lied to her trainers by telling them the sink that was ripped out of the wall was the cat’s fault, it showed she has a cognitive capacity to blame something else to avoid punishment.

An orangutan named Chantek learned about 150 different signs and used them spontaneously and without undue repetition. “Chantek internalized a minimal value system, using signs for GOOD and BAD in appropriate contexts” (Miles). Much like a human child, Chantek prefers to address things with names rather than pronouns. He even invents signs of his own for instance, “eye-drink” means eye drops. Chantek also can point to show objects, which is a uniquely human trait. However, he is very shy so he will not sign in front of strangers.

A bonobo named Kanzi learned communication through the use of a keyboard with lexigrams and learned sign language from watching videos of Koko the gorilla signing. “Bonobos (Panpaniscus) can understand and produce differences in meaning by varying word arrangements” (Ujhelyi). He is believed to understand around 500 words and uses 30-40 daily. Kanzi’s understanding of new sentences is about equal to a human child at the of age two and a half. “Kanzi uses sentences; that is, he follows structured rules in his multi-word utterances (showing the property of duality)”.

(Savage-Rumbaugh). Although Kanzi can make short sentences, he has never tried to describe his feelings or experiences by signing “ I feel, I want or I think”.

Some apes are shy but others are more social by signing with total strangers. At the Welsh Mountain Zoo in Wales, a chimpanzee was filmed signing to a zoo visitor asking him to free it. The chimpanzee is seen in the video motioning to a zoo visitor to unlock the bolt-on what appears to be a glass door and lift the window, so he can be free.

The chimpanzee repeatedly taps on the window to urge the viewers to let him out. The chimpanzee is making sure it is being understood by the visitors by doing repetitive actions and giving longing looks to the people watching.

It is remarkable to be able to communicate with another species and teaching language to apes is beneficial in understanding the nature of language and cognitive and intellectual capacities. Teaching apes sign language also shows that apes can communicate with other species, they just need to be shown how. Overall, the available research supports the idea that great apes can communicate using sign language and comprehend the meaning behind it.

Works Cited

De Luce, J. and Wilder, H.T. “Introduction,” in Language in Primates: Perspectives and Implications. Ed. J. de Luce and H.T. Wilder, pp. 1-17. New York: Springer Verlag, 1983.

Gardner, R.A. and Gardner, B.T. “Teaching Sign Language to a Chimpanzee,” in Language Intervention from Ape to Child. Ed. R.L. Schiefelbusch and J.H. Hollis, pp. 171 – 195. Baltimore: University Park Press, 1979.

Hopkins, W. D., and Cantero, M. (2003), From hand to mouth in the evolution of language: the influence of vocal behavior on lateralized hand use in manual gestures by chimpanzees (Pan troglodytes). Developmental Science, 6:55–61.

Miles, H.L.W. “Language and the Orang-utan: The Old ‘Person’ of the Forest,” in The Great Ape Project: Equality Beyond Humanity. Ed. P. Cavalieri and P. Singer, pp. 42-57. New York: St. Martin’s Press, 1993.

Patterson, F., and Linden, E. The Education of Koko. New York: Holt, Rinehart and Winston, 1981.

Rivas, Esteban. “Recent Use Of Signs By Chimpanzees (Pan Troglodytes) In Interactions With Humans.” Journal Of Comparative Psychology 119.4 (2005): 404-417. PsycARTICLES. Web. 27 Apr. 2013.

Savage-Rumbaugh, S. and Lewin, R. Kanzi: The Ape at the Brink of the Human Mind. New York: John Wiley & Sons, 1994.

Ujhelyi, Maria. Is There Any Intermediate Stage Between Animal Communication and Language?, Journal of Theoretical Biology, Volume 180, Issue 1, 7 May 1996, Pages 71-76.