by Carl Sagan
Boyce Rensberger is a sensitive and gifted reporter for the New York Times whose parents could neither speak nor hear, although he is in both respects normal. His first language, however, was Ameslan. He had been abroad on a European assignment for the Times for some years. On his return to the United States, one of his first domestic duties was to look into the Gardners’ experiments with Washoe. After some little time with the chimpanzee, Rensberger reported, “Suddenly I realized I was conversing with a member of another species in my native tongue.” The use of the word tongue is, of course, figurative: it is built deeply into the structure of the language (a word that also means “tongue”). In fact, Rensberger was conversing with a member of another species in his native “hand.” And it is just this transition from tongue to hand that has permitted humans to regain the ability—lost, according to Josephus, since Eden—to communicate with the animals.
In addition to Ameslan, chimpanzees and other nonhuman primates are being taught a variety of other gestural languages. At the Yerkes Regional Primate Research Center in Atlanta, Georgia, they are learning a specific computer language called (by the humans, not the chimps) “Yerkish.” The computer records all of its subjects’ conversations, even during the night when no humans are in attendance; and from its ministrations we have learned that chimpanzees prefer jazz to rock and movies about chimpanzees to movies about human beings. Lana had, by January 1976, viewed The Developmental Anatomy of the Chimpanzee 245 times. She would undoubtedly appreciate a larger film library.
In the illustration on this page, Lana is shown requesting, in proper Yerkish, a piece of banana from the computer. The syntax required to request from the computer water, juice, chocolate candy, music, movies, an open window and companionship are also displayed. (The machine provides for many of Lana’s needs, but not all. Sometimes, in the middle of the night, she forlornly types out: “Please, machine, tickle Lana.”) More elaborate requests and commentaries, each requiring a creative use of a set grammatical form, have been developed subsequently.
Lana monitors her sentences on a computer display, and erases those with grammatical errors. Once, in the midst of Lana’s construction of an elaborate sentence, her trainer mischievously and repeatedly interposed, from his separate computer console, a word that made nonsense of Lana’s sentence. She gazed at her computer display, spied her trainer at his console, and composed a new sentence: “Please, Tim, leave room.” Just as Washoe and Lucy can be said to speak, Lana can be said to write.
Lana at her computer. The overhead bar, just off the top, must be pulled to activate the console. Dispensers for juice, water, bananas, and chocolate candies are near the base of the console.
At an early stage in the development of Washoe’s verbal abilities, Jacob Bronowski and a colleague wrote a scientific paper denying the significance of Washoe’s use of gestural language because, in the limited data available to Bronowski, Washoe neither inquired nor negated. But later observations showed that Washoe and other chimpanzees were perfectly able both to ask questions and to deny assertions put to them. And it is difficult to see any significant difference in quality between chimpanzee use of gestural language and the use of ordinary speech by children in a manner that we unhesitatingly attribute to intelligence. In reading Bronowski’s paper I cannot help but feel that a little pinch of human chauvinism has crept in, an echo of Locke’s “Beasts abstract not.” In 1949, the American anthropologist Leslie White stated unequivocally: “Human behavior is symbolic behavior; symbolic behavior is human behavior.” What would White have made of Washoe, Lucy and Lana?
These findings on chimpanzee language and intelligence have an intriguing bearing on “Rubicon” arguments—the contention that the total brain mass, or at least the ratio of brain to body mass, is a useful index of intelligence. Against this point of view it was once argued that the lower range of the brain masses of microcephalic humans overlaps the upper range of brain masses of adult chimpanzees and gorillas; and yet, it was said, microcephalics have some, although severely impaired, use of language—while the apes have none. But in only relatively few cases are microcephalics capable of human speech. One of the best behavioral descriptions of microcephalics was written by a Russian physician, S. Korsakov, who in 1893 observed a female microcephalic named “Masha.” She could understand a very few questions and commands and could occasionally reminisce on her childhood. She sometimes chattered away, but there was little coherence to what she uttered. Korsakov characterized her speech as having “an extreme poverty of logical associations.” As an example of her poorly adapted and automaton-like intelligence, Korsakov described her eating habits. When food was present on the table, Masha would eat. But if the food was abruptly removed in the midst of a meal, she would behave as if the meal had ended, thanking those in charge and piously blessing herself. If the food were returned, she would eat again. The pattern apparently was subject to indefinite repetition. My own impression is that Lucy or Washoe would be a far more interesting dinner companion than Masha, and that the comparison of microcephalic humans with normal apes is not inconsistent with some sort of “Rubicon” of intelligence. Of course, both the quality and the quantity of neural connections are probably vital for the sorts of intelligence that we can easily recognize.
The diagram shows the logic tree required for a number of requests to be communicated. The system is both polite and grammatical: requests must be initiated by a “please” and terminated by a period.
Recent experiments performed by James Dewson of the Stanford University School of Medicine and his colleagues give some physiological support to the idea of language centers in the simian neocortex—in particular, like humans, in the left hemisphere. Monkeys were trained to press a green light when they heard a hiss and a red light when they heard a tone. Some seconds after a sound was heard, the red or the green light would appear at some unpredictable position-different each time—on the control panel. The monkey pressed the appropriate light and, in the case of a correct guess, was rewarded with a pellet of food. Then the time interval between hearing the sound and seeing the light was increased up to twenty seconds. In order to be rewarded, the monkeys now had to remember for twenty seconds which noise they had heard. Dewson’s team then surgically excised part of the so-called auditory association cortex from the left hemisphere of the neocortex in the temporal lobe. When retested, the monkeys had very poor recall of which sound they were then hearing. After less than a second they could not recall whether it was a hiss or a tone. The removal of a comparable part of the temporal lobe from the right hemisphere produced no effect whatever on this task. “It looks,” Dewson was reported to say, “as if we removed the structure in the monkeys’ brains that may be analogous to human language centers.” Similar studies on rhesus monkeys, but using visual rather than auditory stimuli, seem to show no evidence of a difference between the hemispheres of the neocortex.
Because adult chimpanzees are generally thought (at least by zookeepers) to be too dangerous to retain in a home or home environment, Washoe and other verbally accomplished chimpanzees have been involuntarily “retired” soon after reaching puberty. Thus we do not yet have experience with the adult language abilities of monkeys and apes. One of the most intriguing questions is whether a verbally accomplished chimpanzee mother will be able to communicate language to her offspring. It seems very likely that this should be possible and that a community of chimps initially competent in gestural language could pass down the language to subsequent generations.
Where such communication is essential for survival, there is already some evidence that apes transmit extragenetic or cultural information. Jane Goodall observed baby chimps in the wild emulating the behavior of their mothers and learning the reasonably complex task of finding an appropriate twig and using it to prod into a termite’s nest so as to acquire some of these tasty delicacies.
Differences in group behavior—something that it is very tempting to call cultural differences—have been reported among chimpanze
es, baboons, macaques and many other primates. For example, one group of monkeys may know how to eat bird’s eggs, while an adjacent band of precisely the same species may not. Such primates have a few dozen sounds or cries, which are used for intra-group communication, with such meanings as “Flee; here is a predator.” But the sound of the cries differs somewhat from group to group: there are regional accents.
An even more striking experiment was performed accidentally by Japanese primatologists attempting to relieve an overpopulation and hunger problem in a community of macaques on an island in south Japan. The anthropologists threw grains of wheat on a sandy beach. Now it is very difficult to separate wheat grains one by one from sand grains; such an effort might even expend more energy than eating the collected wheat would provide. But one brilliant macaque, Imo, perhaps by accident or out of pique, threw handfuls of the mixture into the water. Wheat floats; sand sinks, a fact that Imo clearly noted. Through the sifting process she was able to eat well (on a diet of soggy-wheat, to be sure). While older macaques, set in their ways, ignored her, the younger monkeys appeared to grasp the importance of her discovery, and imitated it. In the next generation, the practice was more widespread; spread; today all macaques on the island are competent at water sifting, an example of a cultural tradition among the monkeys.
Opposite: A chimp with a long blade of grass, used as a tool to prod termites out of their nest.
Photograph by Baron Hugo van Lawick.
Copyright © National Geographic Society
Earlier studies on Takasakiyama, a mountain in northeast Kyushu inhabited by macaques, show a similar pattern in cultural evolution. Visitors to Takasakiyama threw caramels wrapped in paper to the monkeys—a common practice in Japanese zoos, but one the Takasakiyama macaques had never before encountered. In the course of play, some young monkeys discovered how to unwrap the caramels and eat them. The habit was passed on successively to their playmates, their mothers, the dominant males (who among the macaques act as babysitters for the very young) and finally to the subadult males, who were at the furthest social remove from the monkey children. The process of acculturation took more than three years. In natural primate communities, the existing nonverbal communications are so rich that there is little pressure for the development of a more elaborate gestural language. But if gestural language were necessary for chimpanzee survival, there can be little doubt that it would be transmitted culturally down through the generations.
I would expect a significant development and elaboration of language in only a few generations if all the chimps unable to communicate were to die or fail to reproduce. Basic English corresponds to about 1,000 words. Chimpanzees are already accomplished in vocabularies exceeding 10 percent of that number. Although a few years ago it would have seemed the most implausible science fiction, it does not appear to me out of the question that, after a few generations in such a verbal chimpanzee community, there might emerge the memoirs of the natural history and mental life of a chimpanzee, published in English or Japanese (with perhaps an “as told to” after the by-line).
If chimpanzees have consciousness, if they are capable of abstractions, do they not have what until now has been described as “human rights”? How smart does a chimpanzee have to be before killing him constitutes murder? What further properties must he show before religious missionaries must consider him worthy of attempts at conversion?
I recently was escorted through a large primate research laboratory by its director. We approached a long corridor lined, to the vanishing point as in a perspective drawing, with caged chimpanzees. They were one, two or three to a cage, and I am sure the accommodations were exemplary as far as such institutions (or for that matter traditional zoos) go. As we approached the nearest cage, its two inmates bared their teeth and with incredible accuracy let fly great sweeping arcs of spittle, fairly drenching the lightweight suit of the facility’s director. They then uttered a staccato of short shrieks, which echoed down the corridor to be repeated and amplified by other caged chimps, who had certainly not seen us, until the corridor fairly shook with the screeching and banging and rattling of bars. The director informed me that not only spit is apt to fly in such a situation; and at his urging we retreated.
I was powerfully reminded of those American motion pictures of the 1930s and 40s, set in some vast and dehumanized state or federal penitentiary, in which the prisoners banged their eating utensils against the bars at the appearance of the tyrannical warden. These chimps are healthy and well-fed. If they are “only” animals, if they are beasts which abstract not, then my comparison is a piece of sentimental foolishness. But chimpanzees can abstract. Like other mammals, they are capable of strong emotions. They have certainly committed no crimes. I do not claim to have the answer, but I think it is certainly worthwhile to raise the question: Why, exactly, all over the civilized world, in virtually every major city, are apes in prison?
For all we know, occasional viable crosses between humans and chimpanzees are possible.* The natural experiment must have been tried very infrequently, at least recently. If such off-spring are ever produced, what will their legal status be? The cognitive abilities of chimpanzees force us, I think, to raise searching questions about the boundaries of the community of beings to which special ethical considerations are due, and can, I hope, help to extend our ethical perspectives downward through the taxa on Earth and upwards to extraterrestrial organisms, if they exist.
It is hard to imagine the emotional significance for chimpanzees of learning language. Perhaps the closest analogy is the discovery of language by intelligent human beings with severe sensory organ impairment. While the depth of understanding, intelligence and sensitivity of Helen Keller, who could neither see, hear nor speak, greatly exceeds that of any chimpanzee, her account of her discovery of language carries some of the feeling tone that this remarkable development in primate languages may convey to the chimpanzee, particularly in a context where language enhances survival or is strongly reinforced.
One day Miss Keller’s teacher prepared to take her for a walk:
She brought me my hat, and I knew I was going out into the warm sunshine. This thought, if a wordless sensation may be called a thought, made me hop and skip with pleasure.
We walked down the path to the well-house, attracted by the fragrance of the honeysuckle with which it was covered. Someone was drawing water and my teacher placed my hand under the spout. As the cool stream gushed over my hand she spelled into the other the word water, first slowly, then rapidly. I stood still, my whole attention fixed upon the motion of her fingers. Suddenly I felt a misty consciousness as of something forgotten—a thrill of returning thought; and somehow the mystery of language was revealed to me. I knew then that W-A-T-E-R meant that wonderful cool something that was flowing over my hand. That living word awakened my soul, gave it light, hope, joy, set it free! There were barriers still, it is true, but barriers that in time could be swept away.
I left the well-house eager to learn. Everything had a name, and each name gave birth to a new thought. As we returned into the house, every object which I touched seemed to quiver with life. That was because I saw everything with the strange, new sight that had come to me.
Perhaps the most striking aspect of these three exquisite paragraphs is Helen Keller’s own sense that her brain had a latent capability for language, needing only to be introduced to it. This essentially Platonic idea is also, as we have seen, consistent with what is known, from brain lesions, of the physiology of the neocortex; and also with the theoretical conclusions drawn by Noam Chomsky of the Massachusetts Institute of Technology from comparative linguistics and laboratory experiments on learning. In recent years it has become clear that the brains of nonhuman primates are similarly prepared, although probably not quite to the same degree, for the introduction of language.
The long-term significance of teaching language to the other primates is difficult to overestimate. There is an arresting passage in Charles Darwin’s Desc
ent of Man: “The difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind.… If it could be proved that certain high mental powers, such as the formation of general concepts, self-consciousness, et cetera, were absolutely peculiar to man, which seems extremely doubtful, it is not improbable that these qualities are merely the incidental results of other highly-advanced intellectual faculties; and these again mainly the results of the continued use of a perfect language.”
This same opinion on the remarkable powers of language and human intercommunication can be found in quite a different place, the Genesis account of the Tower of Babel. God, in a strangely defensive attitude for an omnipotent being, is worried that men intend to build a tower that will reach to heaven. (His attitude is similar to the concern he expresses after Adam eats the apple.) To prevent Mankind from reaching heaven, at least metaphorically, God does not destroy the tower, as, for example, Sodom is destroyed. Instead, he says, “Behold, they are one people, and they have all one language; and this is only the beginning of what they will do; and nothing that they propose to do will now be impossible for them. Come, let us go down, and there confuse their language, that they may not understand one another’s speech” (Genesis 11:6-7).
The continued use of a “perfect” language … What sort of culture, what kind of oral tradition would chimpanzees establish after a few hundred or a few thousand years of communal use of a complex gestural language? And if there were such an isolated continuous chimpanzee community, how would they begin to view the origin of language? Would the Gardners and the workers at the Yerkes Primate Center be remembered dimly as legendary folk heroes or gods of another species? Would there be myths, like those of Prometheus, Thoth, or Oannes, about divine beings who had given the gift of language to the apes? In fact, the instruction of chimpanzees in gestural language distinctly has some of the same emotion tone and religious sense of the (truly fictional) episode in the movie and novel 2001: A Space Odyssey in which a representative of an advanced extraterrestrial civilization somehow instructs our hominid ancestors.
