“Monkeys … very sensibly refrain from speech lest they should be set to earn their livings.”

-Kenneth Grahame
The Golden Age: Lusisti Satis (1895)

I am a primate. I share ninety-eight percent of my genetic information with the other species of primates, such as chimpanzees, orangutans, and bonobos. Yet, I feel more than just two percent different than these other animals. For one, I have the capacity for language. I have never heard of a nonhuman primate that can write a novel, tell a story, sing a song, or read a newspaper. But just because these other animals fall short of possessing my language expertise, does that mean that other primates do not have any capacity for language?

Human philosophers and linguists throughout the ages, and many still today, do not believe animals other than Homo sapiens have the capacity for language. In fact, many believe language to be the distinguishing feature that sets humans apart from the beasts. René Descartes wrote in the 17th century that animals are mechanical “automata” and do not possess “feelings and reason.”] Three hundred years later, 20th century linguist Noam Chomsky continued the tradition of language’s human-specificity. Chomsky believes the quest to quantify language in apes is in vain; he asks why apes do not use language if they have the ability. (Hart, 1) But perhaps the apes are using their own language. Julien Offray de la Mettrie’s challenge posed to Descartes’ view in 1748 still applies to Chomsky’s camp, over two hundred years later. De la Mettrie cautions that “proof of man’s uniqueness and rationality could be undermined by teaching an ape to speak.” (Rumbaugh, 12) Obviously, apes do not have the full capacity for human language, just as humans do not have the capacity to communicate fluently with apes. And here we stumble upon the primary conundrum of primate language research: What is language?

A specific definition of language is necessary in order to test a primate’s ability of language capability. Language is the ability to communicate with members of an animal’s own species using symbolic output, as well as the ability to perform somewhere along the continuum of language. Considering that language is a function of an animal’s consciousness, researchers must tackle the question of whether primates are conscious. This task proves difficult, although necessary. “Consciousness cannot be understood unless accurately described.” (Savage-Rumbaugh, 910) Sue Savage-Rumbaugh, a renowned researcher of primate language, believes that consciousness “is general among animal species.” (Savage-Rumbaugh, 911) Additionally, Rumbaugh stresses that we can come to a more clear understanding of a primate’s ability for language by shaping an individual ape’s worldview using human culture. This way, we can rate the performance of an ape based on criteria familiar to all humans. “The culture in which an ape is raised will significantly affect the form of consciousness it develops. If reared in a human culture, ape consciousness will be molded according to a form that human beings can recognize.” (Savage-Rumbaugh, 911) Regardless of how well an ape lives up to human linguistic and cultural standards is irrelevant if we assume that primates perform perfectly when communicating with each other. Still, in order for researchers to develop a clear understanding of an ape’s linguistic performance, she must test the ape in accordance to rules she can understand as a human, and as an investigator. Resulting from this trans-species outlook of language capacity is a theoretical “continuum” of language understanding and capability. (Savage-Rumbaugh, 920) Along this continuum reside the capacity to understanding a language and the capacity to produce a language. Considering human language employed on a nonhuman primate, apes might perform better at the former. “Humans first learn to understand a language, then later learn to produce it. It follows, they claim, that animals might learn to understand language better than they learn to produce it.” (Snowdown, 225) The continuum of language ends at human capability and degrades as a gradient. If an animal’s abilities reside somewhere along this line, then that animal is said to have some capacity for language as we know it.

For years, the preferred method for testing a primate’s ability to use symbolic language was to submit apes to experiments in which they interacted with humans. In 1971, Duane Rumbaugh began the “Lana Project” in which researchers attempted to teach a chimpanzee named Lana to use the American Sign Language. Unfortunately, “her signs were often inarticulate and difficult to decipher.” (Savage-Rumbaugh, 911) Others criticized the work “for its lack of control, for the iconicity of the signs not being truly symbolic, and for displaying little true evidence of grammar.” (Snowdown, 220) For example, the controversial symbol for “flower” on the keyboard somewhat resembled a flower. Most of the symbols, however, were entirely abstract. Lana only learned about twenty-five different signs, and exhibited no mastery of the symbols. “It was also not clear why she sometimes made what seemed to be incomprehensible errors and formed nonsensical strings.” (Savage-Rumbaugh, 912) Clearly, Lana could not master the higher level meaning the sign language represents. “Lana’s use of symbols was somehow not humanlike.” (Savage-Rumbaugh, 912) In attempt to salvage the research, Rumbaugh allowed Lana more leeway by allowing her to try various sentence combinations while attempting to communicate a desire. Yet the results show that Lana was not learning from her errors, and “it could take five to fifteen attempts” to arrive at the correct answer. This “absence of systematic elimination” shows a lack of understanding human syntax. D. Rumbaugh went on to develop a “lexical keyboard” containing various pictograph symbols representing real world objects. “The lexical keyboard system … provided a potential means of propelling apes beyond the limitations posed by these other methodologies,” such as sign language. (Savage-Rumbaugh, 911) Although chimpanzees mastered the keyboard easier than the sign language system, research using the keyboard cultivated little evidence for an ape’s understanding of language. In all of these experiments, Lana communicated with a human being, not a member of her own species. Attempts to gauge the language capacity of a chimpanzee using human-primate interaction failed. Researchers have proposed a reason for the disaster.

One objection to the research involving primate interaction with humans is the potential for reward expectation on the part of the primate. Were Lana and the other chimpanzees involved in the primate-human experiments simply responding to Pavlovian stimuli? Perhaps these experiments clouded any evidence for actual language capacity by setting up a positive-feedback loop. Researchers questioned whether the primates were simply using symbols and sign language in order to achieve the goal of getting a food reward or if they grasped the concept of symbolic language in the same manner as a human’s understanding. Michael Beran confirmed these suspicions in 2001 with a study designed to test this exact hypothesis. In fact, Beran actually used Lana, the chimpanzee from D. Rumbaugh’s original study. He found that the chimpanzees did expect a reward. The chimpanzees would become agitated if the human experimenters withheld the reward after a correct response. “What is clear is that both Lana and Mercury (another chimpanzee) had a clear expectation of receiving a food reward when a trial was completed correctly that they did not have when a trial was incorrect.” (Beran, 181) These primates expected a reward, yet all of these experiments were based on primate-human interaction. Could a change in research philosophy solve the problem of reward expectation?

In accordance with the above definition of language, a paradigm shift in research could allow for a greater understanding of primate language. In fact, this revolution would come with the development of primate-primate research, as opposed to the awkwardness of primate-human experiments. In 1983, D. Rumbaugh’s wife, Sue Savage-Rumbaugh, developed what Charles Snowdown of the University of Wisconsin Madison calls a “major breakthrough in the study of language analogues.” (Snowdown, 223) Savage-Rumbaugh endeavored on one such study in 1979. She and other researchers analyzed communication between two chimpanzees named Sherman and Austin. Unlike previous attempts at measuring language competency in chimpanzees, this study did not involve any primate-human interaction during the course of the experiments. “It meant for the first time in the field of animal language, the experimenter was removed as half of every subject-experimenter interaction.” (Savage-Rumbaugh, 913) By eliminating the role of the human, Savage-Rumbaugh undermined the challenges involved with reward procurement on the part of the primate. No longer could critics challenge the experiment’s results on charges of reward expectation. “The issue is no longer one of data, of potential cueing or experimenter effects, or of conditioning.” (Savage-Rumbaugh, 919) In these experiments with Sherman and Austin, experimenters created situations that required the two chimpanzees to communicate to each other using a symbolic language. A keyboard provided the means for communication. The keyboard featured 256 unique symbols. Each symbol represented a common object or concept. One example of an experiment involved a circumstance where one of the chimpanzees knew where food was hidden and the other did not. In order to receive the food, one chimpanzee would have to communicate the location of the food to the other so that the other chimpanzee could locate the food. The chimpanzees nearly always completed the task successfully. After analyzing the data obtained by the experiments, researchers concluded, “symbolic communication of a high level, with the use of an abstract code and with mutual understanding and cooperation, was possible between nonhuman creatures.” Without the primate-primate setup of the experiment, researchers would not have been able to conclude any significant facts about primate communication because human interaction would have tainted the results by creating unrealistic situations. “Linguistic communication necessarily takes place between individuals in a multiplicity of exchanged that cannot be controlled from the outside either by intentionally setting the stage of the preceding stimulus or effecting a particular event.” (Savage-Rumbaugh)

Primates not only successfully use symbolic visual language, such as with the aforementioned keyboard, but also vocally. Although nonhuman primates lack the proper vocal chords to make the broad range of human sounds, research has shown bonobos use audible messages to communicate with members of their own species. In 2000, investigators led by Jared Taglialatela painstakingly analyzed over four hundred hours of bonobo vocalization. They found that the sounds bonobos use in nature alter substantially during unique situations. Statistical analysis verified the linguistic implications of the sounds, or phrases. “Structural differences do exist between those vocalizations produced in different communicative contexts. These results suggest that the vocalizations possess lexical significance.” (Taglialatela, 95) Taglialatela used computer technology to decipher the hidden meaning in what sounds like indiscriminate shrieks to the human ear. What sounds like a casual grunt to a human primate actually means “banana” to a bonobo primate. “A vocalization produced in conjunction with a gesture to a banana was assigned to the communicative context, ‘banana.’” (Taglialatela, 95) Primates, human and nonhuman alike, have the capacity to understand symbolic visual language as well as their own vocal language.

In addition to communicating among themselves with their natural vocal communication system, researchers have evidence of primates teaching sign language to their peers of the same species. In 1974, researchers at the Institute of Primate Studies in Norman, Oklahoma, witnessed a sign language competent chimpanzee teach another chimpanzee signs. “Manny, a young chimpanzee in the colony, has acquired from Washoe the ‘come hug’ sign, which is used correctly when the chimpanzees greet one another or are engaged in mutual comforting.” (Sebeok, 279) This drifting of contagious symbolism between human primates and chimpanzees is the most stunning verification of language in primates. Humans using signs to communicate with each other is language. And when the technique is transmitted to an ape, it remains language.

Whether the reason for the human’s adamant rejection of primate language is due to taxonomic arrogance or cross-species misunderstanding, scientific research shows that primates utilize the power of language for the same reasons as humans: for survival, culture, and play.


Work Cited

Hart, Stephen. “Apes may hold clues to language’s origins.” BioScience, June 1998 v48 i6 p437(2)

Rumbaugh, D.M. Language Learning by a Chimpanzee. New York: Academic Press. 1997.

Savage-Rumbah, S., Fields, W. M., Taglialatela, J.P. (2000). Ape consciousness-human consciousness: A perspective informed by language and culture. American Zoologist, 40 (6): 910-921.

Sebeok, T.A., Umiker-Sebeok, J.U. Speaking of Apes. New York: Plenum Press. 1980.

Snowdown, C.T. (1990). “Language capacity of Nonhuman Animas.” Yearbook of Physical Anthropoloby 33: 215-243

“Vocalization production and usage in language-competent, captive bonobos (Pan paniscus).” American Journal of Primatology, 51 (Supplement 1): 95 Abstract.

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