Kanzi: The Ape at the Brink of the Human Mind

by Sue Savage-Rumbaugh

  I soon learned, however, that Iain was as concerned about people failing to understand his perspective on archeology as I was about having my chimp work misunderstood. Consequently he had sought the very first opportunity to drive home the point that an event as salient as the origin of language, which took place in prehistory, is likely to have left its mark on prehistory, and that this line of evidence had not received sufficient attention from people interested in language origins—particularly psychologists. I learned this only because that evening after supper I decided to muster my courage and go up and speak to Iain directly.

  I started out by asking him how he could be so peremptorily derogatory about apes when he knew next to nothing about them. How was it he could so blithely assume that symbol capacities did not exist in creatures before they began to leave permanent statues, paintings, or other artifacts in the archeological record? Much to my surprise, Iain was not nearly as bombastic when approached one on one. I realized that he probably had been so stiff and argumentative because he was in front of the group. It seemed to me that human males often responded that way during initial encounters—just as do chimpanzee males. Unlike every other Chomskian I had met, Iain readily allowed that there was a great deal he did not know about apes, though he held fast to his notion that only man could symbolize.

  Although our original intellectual positions seemed very far apart—with Iain proposing a late, sudden origin of language while I favored an early, more gradual efflorescence—we began that day one of the most productive, free-flowing exchanges of ideas I’ve been privileged to enjoy with a colleague. We both listened, and as a result began to modify our ideas. Iain wasn’t afraid to argue forcefully for his views, and neither was I, but somehow this did not keep us from talking to one another, as is so often the case with scientists who disagree. Why not? I think because we each accepted the other’s directness, even bluntness, without offense. We did so out of a mutual recognition of the integrity of the other person’s efforts. It was a remarkable week, one that may become a milestone in our important intellectual journey toward understanding the human mind—with the human/nonhuman boundary suffering badly.

  Fortunately, it was not up to me alone to convince the gathering’s skeptics of the range and inventiveness that characterize ape intelligence. I was aware, of course, of chimpanzees’ penchant for using tools, but it wasn’t until Bill McGrew itemized the different types of tools they use, and in the many different circumstances, that its import became fully clear to me, and to others, too. “Chimpanzees are the only nonhuman species in nature to use different tools to solve different problems,” said McGrew, a primatologist at the University of Stirling, Scotland. “They go beyond using the same tool to solve different problems (for example, a sponge of leaves to swab out a fruit-husk or a cranial cavity) or different tools to solve the same problem (for example, probes of bark or grass or vine to fish for termites). Thus, they have a toolkit”16

  It was Christophe Boesch, of the University of Basel, Switzerland, who grabbed the most attention with his reports of chimpanzees in the tropical rain forest of the Taï National Park, in the Ivory Coast, West Africa. The chimps of the region exploit a rich food resource, that of Coula and Panda nuts, which have to be cracked open to give access to the kernels. The animals gather the nuts and then place them one by one in a depression in an exposed tree root or branch on the forest floor (the anvil). They then pound the nuts one by one with a stone or short branch (the hammer). A skilled practitioner can garner as many as 3800 calories a day in the nut season.

  It takes time to become skilled at nut cracking, however—often as much as eleven years. The animals’ persistence in developing the skill is an indication of the value of the nuts. One of the great advantages of nut cracking is that it allows a mother to provision for her offspring. Coula and Panda nuts are common in Western and Central Africa, but it is only the Taï forest chimp population that has learned to exploit the resource. This is a striking example of a cultural difference between populations. Even more dramatic, however, was Boesch’s observation of mothers actively teaching their offspring the skills of nut cracking.

  Boesch told us how, on one occasion, he saw Salomé and her son Satre cracking Panda nuts. Salomé cracked most of them, and when Satre tried with a partially opened nut, he placed the nut improperly on the anvil. Before he could strike it with the stone hammer, “Salomé took the piece of nut in her hand, cleaned the anvil, and replaced the piece carefully in the correct position,” explained Boesch. “Then, with Salomé observing him, he successfully opened it and ate the second kernel.”

  On another occasion Boesch saw Nina, daughter of Ricci, having difficulty opening nuts using an irregular hammer. Nina kept shifting her position, turning the hammer around in her hand, but still was frustrated by her lack of success. After eight minutes, Ricci joined Nina, who immediately gave the hammer to her mother. Ricci took the hammer and, with deliberate slowness, turned the hammer to the most effective position, cracked some nuts (which she shared with Nina), and handed the hammer back. Nina took the hammer, held it in the position demonstrated by her mother, and proceeded to open four nuts. This example is particularly interesting, said Boesch, because “the mother, seeing the difficulties of her daughter, corrected an error in her daughter’s behavior in a very conspicuous way and then proceeded to demonstrate to her how it works with the proper grip.”17

  These instances are the first field examples of active teaching—another behavior supposedly unique to humans—in a nonhuman primate population. As Kathleen Gibson kept remarking throughout the conference, “Every time I learned something unique about humans, it wasn’t unique!” The gap was closing, or at least bridgeable.

  As the week wore on, I grew anxious for an opportunity to show the video of Kanzi: Sydel Silverman finally relented under my repeated requests and promised that I could show my tape. I had lugged an American machine with me, along with all the required adapters, so I could run the tape (which has different specifications from European videotapes). I had been testing the system in my hotel room a few days before I was due to show the tape. Disaster struck. I had left the machine plugged in when a series of power outages—common in the region, I learned later—destroyed a key component in the set. Philip Lieberman, an expert on the structure of the vocal tract and a professor at Brown University, helped me search for replacement parts in the local town. He stripped the set down, put in the new parts, reassembled it all—but it still failed to work. In desperation, I called LRC (the Language Research Center, my lab in Georgia) and asked if a tape could be transformed to European specifications and sent express to Cascais. It arrived late, not until the very last day.

  With the tape in hand, I was now ready for Kanzi to demonstrate to a critical but finally open-minded audience just why the remaining bricks in the constantly patrolled man/animal wall should be cast aside.

  2

  The Meaning of Words

  I first saw chimpanzees in the St. Louis “monkey show” when I was about eight years old. They rode a motorcycle and walked on stilts. They wore clothes and sometimes had temper tantrums in which they began screaming at each other in the middle of the show. I remember thinking that the things they were doing looked like fun, but that the chimpanzees themselves did not look as if they were having a good time, except for the one who was permitted to ride the motorcycle. He went round and round with his chin tucked down and a rather fiendish grin on his face that I can still recall. He jumped the bike through a hoop of fire for the finale—and all this was before Evel Knievel.

  I wondered how the chimps felt about what they were doing. I tried hard to broach that question with my parents, but they seemed to think it was an odd question and dismissed it, saying something about how it was not really possible to tell exactly how animals felt about things, since they could not talk.

  I also saw the lion and tiger show, in which a trainer with a whip kept ten different large cats on pedestals while each too
k a turn doing tricks. The most impressive trick was when one of them jumped through a flaming hoop. In contrast to the chimpanzee on the motorcycle, the cat seemed afraid. He readily jumped through the hoop without the fire, but when it was lit, he hesitated and had to be persuaded with a great deal of whip cracking by a trainer who was sweating profusely. At the time, I had no sense of how dangerous apes can be; neither, I think, did the rest of the audience.

  The big cats, however, looked perfectly capable of swallowing a man, and they all appeared quite hungry. Consequently, the power the trainer could wield over them with only a whip amazed me. I noted that the trainer of the chimpanzees did not use a whip and the chimpanzees did not threaten him, as did the lions. I never really wondered how the big cats felt about the show, as I did with the chimpanzees; I did wonder why they tolerated being in a show.

  My next experience with live chimpanzees occurred when I became a graduate teaching assistant in psychology at the University of Oklahoma, in Norman. Roger Fouts, who had recently transferred to Oklahoma from the University of Nevada, arrived in class one day carrying Booee, who was a little more than three years old. Roger set Booee down on a table and produced a series of objects, including a hat, a shoe, and a ring of keys. He held up each object and asked Booee to name it. The class, myself included, was quite taken aback as Booee formed his hands into signs for the objects, using the American Sign Language (ASL) system. Although he knew the names of all the objects, Booee was really interested only in the keys. He wanted to play with them and kept signing “keys” over and over while holding his hand out for them. While I wondered whether he really knew the other words that he was signing, it seemed pretty clear that he understood “keys.”

  The time was 1970, and prior to seeing Booee in class I had heard little of the so-called ape-language studies that had begun in the late 1960s. My image of apes—based on the shows I had seen at the zoo and on television—was that of acrobatic monkeys. I thought of apes as smart dogs with hands and goofy faces. But the ape before me was different. He wasn’t cavorting on a stage or walking around in a coat with a large hat down over his eyes, mimicking a human character. He was sitting calmly on a table in front of nearly one hundred people and making a different sign each time Roger held up a different object. Roger had shown us the signs in advance, so we could see for ourselves that Booee was correct almost every time. After watching Booee do this, and noting the expressions on his face as he looked out over the audience, I knew at once that this creature had to possess sentience that all my life I had assumed was to be found only among humankind.

  As impressive as Booee’s apparent language abilities were, even more intriguing was the nature of the social contract between Booee and Roger. Being the oldest in a family of seven siblings, I had been responsible for much of the caretaking of my younger siblings. This responsibility necessarily gave me a clear understanding of the typical behavior of young children, and the means they use to communicate even before they can speak. Seeing Booee with Roger that day was something like having a professor reveal to you that one of his children was learning impaired with severe speech difficulties and a few minor physical deformities. The real news, however, was not that this “child” was impaired, but that this child was not a human being by physical standards, regardless of whether or not his behavior suggested otherwise. Watching Booee and Roger reminded me of the many times I had taken my younger brothers and sisters on outings as they were learning to talk; Booee was just as playful and inventive as they had been.

  I was attracted to psychology, in part, because of the experiences I encountered helping to raise so many siblings. The development of human behavior intrigued me, particularly the effect of rearing on the development of the human mind and intellectual capacities. When I saw Booee I decided to take Roger up on his request for volunteers to work at the “Chimp Farm.” This chimp farm, owned by Dr. Bill Lemmon, a clinical psychologist, was located about fifteen minutes outside of Norman, Oklahoma. There approximately thirty chimpanzees resided, along with several species of monkeys, lesser apes, peacocks, pigs, and various other animals.

  On my first visit to the chimp farm Roger put me in a very small outdoor cage (two-by-four-by-six feet) with Booee and a bowl full of raisins. He showed me how to get Booee to practice the signs he was being taught. I was asked to hold up the object, then take Booee’s hands and place them in the appropriate configuration for the sign that corresponded to the object I had displayed, and then quickly give Booee a reward. There were a number of different objects Booee was learning and my job was to show each one to Booee, in a random order, and then guide him into making the correct sign. Once I could easily guide his hands into the proper place, I was asked to “fade out” the guidance slowly, expecting Booee to do more and more of the work, until finally he would make the sign all on his own whenever I held up the object.

  Booee was not very interested in making the signs I was supposed to teach him, nor did the fading technique seem to be as effective as Roger had promised. Playing was a far more effective way to spend one’s time in Booee’s view, so I soon began playing with him, after each batch of correct signs, to keep his interest. One time he hung by his hands from the top of the cage and did a 360° turn while we were playing. I laughed and, wanting to see that again, held up my hand and spun my index finger around in a 360° arc and pointed to the top of the cage. Booee at once grasped my intent and proceeded to repeat his flip for my benefit. This gesture was not one of Booee’s signs. In fact, no one had ever made that sort of gesture or request to him before. He had been asked to sign, but never to do things that entailed his entire body. Yet he was immediately able to comprehend the meaning of my gesture—repeat that flip you did up there.

  I felt so taken aback by the alacrity with which he understood what I meant that I simply stood there, rooted in place, staring at him transfixed. The implications of his ability to comprehend such a novel gesture began to race through my mind, leaving me somewhat shaken. Finally Booee decided to take advantage of my rapt state and began to steal the raisins. That brought me back to the necessity of dealing with an ape in the immediate time frame that they, like children, typically insist upon. That night, as I lay awake thinking over all of the things I had seen apes do that day, and how different the “signing chimps” appeared to be from those who had no signs, I knew deep within me that I would work with apes the rest of my life in some manner. For a long time I had felt, in a vague but ever-present way, that there was something I should be about, but that I had not yet discovered it. That night I knew, without doubt, that I had finally found it, and that it was apes.

  Booee lived on an island with four other young chimpanzees, Thelma, Cindy, Bruno, and Washoe. When they were not engaged in signing lessons, these four chimps were taken, by boat, back to the island where they played and slept. Roger was attempting to determine if chimpanzees other than Washoe could learn sign language. Since it took a long time, and a great deal of practice for these chimpanzees to learn signs, Roger needed a lot of help. That was why he had brought Booee to class, to help solicit volunteers.

  Roger explained to the class that in Nevada he had worked with Allen and Beatrice Gardner, who had initiated an ape-language project in 1966 with a wild-born female chimp called Washoe. By 1972 Washoe had become something of a simian celebrity, with an American Sign Language vocabulary of some 150 signs and an apparent ability to make up novel sentences, albeit short ones. Roger brought Washoe to Oklahoma with him in 1970 and began to teach ASL to three other young chimps, including Booee.

  As I began to read the relevant literature, with guidance from Roger, I became even more keenly aware of the implications of human-ape communication. It seemed to offer an insight into the nature of language and even to the essence of humanity itself. There is a long history of this kind of fascination—and specifically in the notion of teaching language to apes. For instance, an entry in the diary of Samuel Pepys, dated 24 August 1661, records his reactions o
n seeing an ape in London, one of the first to have been brought back to the Western world. He describes the ape (probably a chimpanzee) as being “a great baboone” but notes how humanlike it was. He wrote: “I do believe it already understands much english; and I am of the mind it might be taught to speak or make signs.”

  Such suggestions were subsequently to be made many times, often as a passing comment of this kind. The most influential proposal, however, was by the pioneering primatologist Robert Yerkes. In a book called Almost Human, published in 1925, he noted apes’ great intelligence, speculated on their cognitive potential to form language, and recognized the anatomy of their vocal tract as a barrier to speech. “I am inclined to conclude from the various evidences that the great apes have plenty to talk about, but no gift for the use of sounds to represent individual, as contrasted with racial, feelings or ideas,” he wrote. “Perhaps they can be taught to use their fingers, somewhat as does the deaf and dumb person, and thus helped to acquire a simple, nonvocal, ‘sign language.’”1

  Four decades later, the Gardners put Yerkes’ suggestion to the test. Washoe lived in a trailer in the Gardners’ backyard and experienced much of the life of a child, surrounded by playthings and language. The Gardners and their helpers taught Washoe a limited ASL by molding her hands into the appropriate sign in the presence of an object. She was often rewarded for success with some tidbit of food. It was a laborious business, requiring repeated presentation of the object and repeated molding of the hands. A single sign was taught at a time. Slowly she built a vocabulary, rising from four signs after seven months, to thirty after almost two years, and peaking at about 150 after four years. By that time, 1970, Washoe had become too large and boisterous to be easily handled in the Gardners’ trailer, so she was moved to the Institute for Primate Studies, in Oklahoma, where Roger continued working with her in the company of the other apes he was hoping would also learn to sign.