Kanzi: The Ape at the Brink of the Human Mind (29 page)

We first detected what seemed like spoken word comprehension when Kanzi was one and a half years old. We began to notice that often, when we talked about lights, Kanzi would run to the switch on the wall and flip it on and off. Later he simply looked at the light switch on hearing the word, apparently visually forming the pairing. How was this different from what we and others had seen in other apes? Was Kanzi not responding to some undetermined contextual cues? At first we thought this must be the case. However, there were differences. Sherman and Austin responded to speech and contextual information when someone was talking to them or saying something of relevance to or about them. They often responded appropriately to queries like, “Do you want to go outdoors?” “Please don’t push the TV set,” and “Stop tickling so hard.” Kanzi also responded in this manner, but in addition, he seemed to be “listening in” on conversations that had nothing to do with him. For example, I once asked another caretaker if “someone had left the lights on last night” and then noted that Kanzi was gazing at the light switch, even though neither I nor anyone else had done so, and in fact we had not even been discussing the particular light that he was noting.

It was what seemed to be this uncanny ability to “listen in” on conversations that were not directed to him, and indeed ones that he was not supposed to pay attention to, that first began to convince me that Kanzi was processing sounds in a manner that I had not experienced in other apes—even in those who had been
reared in human homes. I believed, however, that this was not possible. The prevailing theory of the time was that of Phillip Lieberman, who asserted that vocal and auditory capacities co-evolved in all creatures. According to Lieberman, the auditory system, composed of the inner ear and the auditory cortex, was capable of processing sounds in an efficient manner only if they corresponded to the types of signals that a species made with its vocal tract. An animal’s auditory comprehension was, so to speak, tuned to the capacity of its throat by co-evolution of the communicative process. This theory seemed very reasonable and it explained, for me, why Sherman and Austin had difficulty understanding words even though we spoke to them constantly.

As time passed, Kanzi appeared able to understand more and more spoken words. Finally, I could no longer ignore the fact that what Kanzi was doing really did not fit within the standard theory and that it was not like the kind of apparent comprehension or partial comprehension that I had encountered in Sherman and Austin or Lucy and Washoe. Kanzi had become so proficient that not only was he listening in on conversations that were not directed to him, he was beginning to translate some of the words we said on the keyboard. For example, one afternoon someone approached me to tell me about a fight that had occurred between Sherman and Austin. Kanzi listened, then went to his keyboard and said
Austin
and gestured
go
, pointing in the direction where Austin and Sherman were housed. Another time, someone mentioned in passing that Kanzi had learned how to turn the light on and off. He immediately went to his keyboard and hit the key for light and then gestured toward the light switch. In response, we had to do what many parents do when they don’t want their children to overhear; we began to spell out some words around Kanzi. Kanzi, like most children, recognized that we were doing this to avoid his listening and simply began to listen all the harder.

At this point we decided to test Kanzi’s speech comprehension carefully and with controls, just as we had previously done with Sherman and Austin. We didn’t train Kanzi for this test, nor did we offer rewards for correct answers. We simply showed him an array of three photographs and lexigrams and then spoke the word to
indicate which one he was to give us. We performed three testing sessions, in which our requests alternated between spoken English and lexigrams. The tests included thirty-five different items, used in 180 trials in English and 180 with lexigrams. Kanzi scored 95 percent correct on the lexigram trials and almost as well, 93 percent, on the English trials. We were able to determine that Kanzi understood 150 spoken words at the end of the seventeen-month period. By comparison, Sherman and Austin were correct 98 percent of the time they were shown a symbol and asked to find the corresponding photo from an array of two or three pictures. However, when we used spoken English to ask for a particular photo, they appeared to guess. They hesitated, tried to look for cues, and asked us to turn the keyboard on. When all else failed, they would simply select the nearest or most interesting picture. Their overall score was near 30 percent, as one would expect if they were simply selecting the photos randomly.

Kanzi’s ability to comprehend spoken English is part of the explanation of the larger phenomenon, namely, his humanlike acquisition of language capacity. Comprehension aided the emergence of the productive skill in Kanzi, as it does in humans, central to which is the understanding that words and lexigrams are referential and can be used as a mode of symbolic communication.

This discovery, another first for Kanzi, clearly would force us to rethink our ideas even further about language and about human uniqueness. “If an ape can begin to comprehend spoken English without being so trained, and was able to do more than emit differential motor responses on cue, it would appear that the ape possessed speech and language abilities similar to our own,” I later commented with my colleagues, in a scientific paper. “Even if the ape was unable to speak, an ability to comprehend language would be the cognitive equivalent of having acquired language.”
⁵

The amount of time and effort that had gone into the first four years of rearing and testing Kanzi had exceeded that in any other published study I had undertaken, and the resulting body of data was the most extensive. I felt ready to present what I
considered to be a strong case for a reevaluation of the language capacities in apes. Five years had passed since Herbert Terrace had published his famous paper in
Science
, in 1979, which concluded that, despite many claims, no one had demonstrated language in apes. I therefore selected
Science
as the most appropriate journal to which to submit a report of the work.

I prepared a manuscript titled “Spontaneous Language Acquisition by a Pygmy Chimpanzee,” and in December 1984 sent it to the editorial offices of
Science
, in Washington, D.C. I believed that the findings with Kanzi should at least reopen the door to the consideration of language skills in other species. “These results indicate that the propensity of the pygmy chimpanzee for the acquisition of primitive language skills is considerably in advance of that yet reported for other apes,” we wrote. “Language acquisition in the pygmy chimpanzee seems to be accompanied (and facilitated) by the ability to understand spoken English.” We pointed out that this was the first report of an ape with these abilities, and that the results had important implications for the evolution of language capacities.

Three months later, we received a rather curt rejection letter from one of the staff editors at
Science
. Two researchers had reviewed the manuscript. The first reviewer acknowledged that we were reporting important new information that was potentially significant to progress in the field. However, the review followed this with a blizzard of specific criticisms which, it suggested, must be addressed if the paper was to be published. The second review asserted that our claim for spontaneous language acquisition in a nonhuman species was not new.

How could anyone who knew anything about the field suggest that spontaneous acquisition was not novel? The reviewer stated that he/she could not envision any way in which a lexigram system could lead to the emergence of linguistic communication, thus there could be no validity to our findings, regardless of the data we presented. I wrote to the editor at
Science
and pointed out the second reviewer’s apparent bias, and asked that the rejection decision be reconsidered. In mid-April we received a second rejection letter.

In the world of scientific publication,
Science
represents
one of the two most widely circulated and respected general journals. The second one is
Nature
, which is published in London. We therefore recast our manuscript, to take account of some of the suggestions the first reviewer had made, and mailed it to London in May. In July we received a letter from an editor at
Nature
, saying “After careful consideration ... we have concluded that publication in
Nature
would not be appropriate.”

We had no better luck with the
Journal of Comparative Psychology
, whose reviewers displayed the same mix of general negativism and incredulity in their comments with which we were by now becoming quite familiar. Finally, I submitted a much more detailed and extensive revision to the
Journal of Experimental Psychology
, along with the previous reviews I had received, so that the editor could see the difficulties that lay ahead. Most, if not all, of the other reviews appeared to have been written by people in the field of ape language. It seemed that, for the most part, they simply refused to believe what was being said about Kanzi. They did not raise methodological or philosophical objections; they simply denied the validity of our findings outright.

The editor of the
Journal of Experimental Psychology
responded by sending the manuscript to well-recognized experimental psychologists who were not in the field of ape language. All reviewers accepted the validity of the basic phenomena and the data that documented it, and the article was published.

Terrace had done the field of ape-language research a favor with his 1979
Science
paper. But instead of accepting what he said in it, which was that many things that had been accepted initially without question needed to be readdressed more carefully, many had inferred that apes were incapable of language capacity. Period. Few were therefore prepared to try to understand the significance of what Kanzi was doing.

Meanwhile Kanzi continued to acquire new symbols, to understand more complex sentences, and to form combinations that appeared to have some regularities to them. Knowing that these skills needed systematic study, I solicited the help of Patricia Greenfield, a linguist at the University of California, Los Angeles,
who had worked with me previously on an analysis of Sherman and Austin’s data.

Patricia had done pioneering work in language acquisition in children, demonstrating, against prevailing orthodoxy, the great communicative content of single-word utterances in infants. She had pointed out that although single words by themselves might convey limited information, they were usually uttered within an informative social context, including gestures of various kinds. As a result of her insights with children, Patricia became one of the few linguists to support language performance in apes, where single-word utterances constitute the great majority of communication. As with children, the single words of apes were typically accompanied by other forms of communicative information. For those prepared to listen, ape-language research derived a degree of linguistic credibility from Patricia’s theories that it might not otherwise have enjoyed.

The problem I faced at this point, however, was how to establish credibility for what Kanzi had achieved. For me, the massive amount of data we had collected carried undeniable conclusions, and yet, people seemed unwilling even to consider them. “What can we do with this data that will help people understand the kinds of things that Kanzi is able to do?” I asked Patricia one day. We were poring over the pages and pages of novel combinatorial utterances that now characterized part of our database on Kanzi. “There
must
be something we can do,” she replied emphatically. “Let’s start classifying these combinations and see what we come up with.”

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