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کتاب: آیا ما به اندازه ی کافی باهوش هستیم که بدانیم حیوانات چقدر باهوش هستند؟ / فصل 4
آیا ما به اندازه ی کافی باهوش هستیم که بدانیم حیوانات چقدر باهوش هستند؟
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4TALK TO ME
Speak and I shall baptize thee!
—French Bishop to a chimpanzee, early 1700s1
We associate research in the natural habitat with sacrifice and bravery, since fieldworkers must tackle the unpleasant and dangerous creatures of the tropical rainforest, from bloodsucking leeches to predators and snakes. By contrast, students of captive animals are thought to have it easy. But we sometimes forget how much courage it takes to defend one's ideas in the face of staunch opposition. Most of the time this occurs just among academics, which is disagreeable rather than hazardous, but Nadia Kohts faced lethal risks. Her full name was Nadezhda Nikolaevna Ladygina-Kohts, and she lived and worked early last century in the shadow of the Kremlin. Under the sinister influence of the would-be geneticist Trofim Lysenko, Joseph Stalin had many a brilliant Russian biologist either shot or sent to the Gulag for thinking the wrong thoughts. Lysenko believed that plants and animals pass on traits gained during their lifetime. The names of those who disagreed with him became unmentionable, and entire research institutes were closed down.
It was in this oppressive climate that Kohts, with her husband Alexander Fiodorovich Kohts—founding director of Moscow's State Darwin Museum—set out to study ape facial expressions, inspired by The Expression of the Emotions in Man and Animals by that bourgeois Englishman, Charles Darwin. Lysenko was distinctly ambivalent about Darwin's theory, some of which he labeled "reactionary." Staying out of trouble became a major preoccupation of the Kohtses, who hid documents and data among their taxidermy collection in the museum basement. They wisely put a large statue of the French biologist Jean-Baptiste Lamarck—famous proponent of the inheritance of acquired characteristics—at the museum entrance.
Kohts published in French, German, and most of all her native Russian. She wrote seven books, of which only one was translated into English, long after its appearance in 1935. The English version of Infant Chimpanzee and Human Child, edited by me, appeared in 2002. The book compares the emotional life and intelligence of a young chimpanzee, Joni, with that of Kohts's little son, Roody. Kohts studied Joni's reactions to pictures of chimpanzees and other animals, and to his own mirror image. Even though Joni was probably too young to recognize himself, Kohts describes how he would entertain himself in front of his reflection by pulling weird faces and sticking out his tongue.2
Kohts is little known compared to Wolfgang K?hler, who conducted his groundbreaking ape research from 1912 through 1920. I wonder what she knew about it while working in Moscow from 1913 until Joni's premature death in 1916. While K?hler is widely recognized as a pioneer of evolutionary cognition, pictures of Kohts's work leave little doubt that she was on exactly the same track. One of the museum's glass cases features Joni's mounted body surrounded by ladders and tools, including sticks that fit into each other. Was Kohts overlooked by science due to her gender? Or was it her language?
I learned about her from the writings of Robert Yerkes, who came to Moscow to discuss her projects through an interpreter. In his books, Yerkes described Kohts's work with the greatest admiration. There is a good chance, for example, that Kohts invented the matching-to-sample (MTS) paradigm, a staple of modern cognitive neuroscience. MTS is nowadays being applied to both humans and animals in countless laboratories. Kohts would hold up an object for Joni, then hide it among other objects in a sack and let him feel around to find the first one. The test involved two modalities—vision and touch—demanding that Joni make a choice based on his memory of the previously seen model.
Nadia Ladygina-Kohts was a pioneer in animal cognition, who studied not only primates but also parrots, such as this macaw. Working in Moscow at around the same time that K?hler conducted his research, she remains far less known.
My own fascination with this unsung hero's work took me to Moscow, too. I received a behind-the-scenes tour of the museum, where I leafed through private picture albums. Kohts was (and is) much beloved in her country, where she is widely recognized as the great scientist that she was. My biggest surprise was to learn that she owned at least three large parrots. Pictures show her accepting an object handed to her by a cockatoo, and her holding out a tray with three cups toward a macaw. The parrots would sit opposite her, on a table, while Kohts held a small food reward in one hand and a pencil in the other, scoring their choices as she tested their ability to discriminate among objects. I checked with our contemporary expert on Psittaciformes, the American psychologist Irene Pepperberg, but she had never heard of Kohts's parrot studies. I doubt that anyone in the West ever suspected that bird cognition, too, was studied in Russia well before it became more widely known.
Alex the Parrot
I first met Alex, the African gray that Irene raised and studied for three decades, on visits to her department from a nearby university. Irene had bought the bird in a pet store, in 1977, and was setting up an ambitious project that would open the public eye to the avian mind. It ended up paving the way for all subsequent studies of bird intelligence, because until then the general opinion had been that bird brains simply don't support advanced cognition. Due to their lack of much of anything that looks like a mammalian cortex, birds were viewed as well endowed with instincts yet poor at learning, let alone thinking. Despite the fact that their brains can be quite sizable—the African gray's is the size of a shelled walnut, with a large area that functions like a cerebral cortex—and that their natural behavior offers ample reason to question the low opinion of them, the different brain organization of birds has been held against them.
Having myself kept and studied jackdaws—members of that other large-brained bird family, the corvids—I have never had any doubt about their behavioral flexibility. On walks through the park, my birds would tease dogs by flying right in front of their heads, just out of reach of their snapping mouths, to the surprise and chagrin of the dog owners. Indoors, they would play object hiding with me: I would hide a small item, such as a cork, under a pillow or behind a flower pot, while they would try to find it, or vice versa. This game relied on the well-known food-caching talents of crows and jays but also suggested object permanence: the understanding that an object continues to exist even after it has disappeared from view. The extreme playfulness of my jackdaws hinted, as it does with animals in general, at high intelligence and the thrill of a challenge. Visiting Irene, I was quite prepared to be impressed by a bird, therefore, and Alex did not disappoint. Cockily sitting on his perch, he had begun to learn labels for items such as keys, triangles, and squares, saying "key," "three-corner," or "four-corner" whenever these objects were pointed out.
At first sight, this came across as language learning, but I am not sure this is the right interpretation. Irene didn't claim that Alex's talking amounted to speaking in the linguistic sense. But of course, the labeling of objects is very much part of language, and we should not forget that once upon a time linguists defined language simply as symbolic communication. Only when apes proved capable of such communication did they feel the need to raise the bar and add refinements such as that language requires syntax and recursivity. Language acquisition by animals became a huge topic that drew enormous public interest. It was as if all questions about animal intelligence boiled down to a sort of Turing test: can we, humans, hold a sensible conversation with them? Language is such a marker of humanity that an eighteenth-century French bishop was ready to baptize an ape provided he could speak. It surely was all that science seemed to care about in the 1960s and 1970s, resulting in attempts to talk with dolphins and teach language to a multitude of primates. Some of this attention turned sour, however, when the American psychologist Herbert Terrace, in 1979, published a highly skeptical article about the sign-language capacities of Nim Chimpsky, a chimpanzee named after American linguist Noam Chomsky.3
Terrace found Nim a boring conversationalist. The vast majority of his utterances were requests for desirable outcomes, such as food, rather than expressions of thoughts, opinions, or ideas. Terrace's surprise at this was by itself rather surprising, however, given his reliance on operant conditioning. Since this is not how we teach children language, one wonders why it was used for an ape. Having been rewarded thousands of times for hand signals, why wouldn't Nim use these signals to obtain rewards? He simply did what he was taught. As a result of this project, however, the voices pro and contra animal language were getting louder by the day. To find a bird voice among this cacophony threw many people off, because while apes obviously don't talk, Alex carefully pronounced every word. Superficially, his behavior resembled language more than that of any other animal, even if there was little agreement about what it actually meant.
Irene's choice of species was intriguing since Doctor Dolittle, the central character of a series of children's books, owned an African gray, named Polynesia, who taught the good doctor the language of animals. Irene had always been attracted to these stories and as a child already presented her pet budgie with a drawer full of buttons to see how the bird would arrange them.4 Her work with Alex grew straight out of her early captivation with birds and their taste in colors and shapes. But before discussing her research further, let me briefly dwell on the desire to talk with animals—a desire often expressed by scientists working on animal cognition—as it relates to the deeper connection often assumed between cognition and language.
Oddly enough, this particular desire must have passed me by, because I have never felt it. I am not waiting to hear what my animals have to say about themselves, taking the rather Wittgensteinian position that their message might not be all that enlightening. Even with respect to my fellow humans, I am dubious that language tells us what is going on in their heads. I am surrounded by colleagues who study members of our species by presenting them with questionnaires. They trust the answers they receive and have ways, they assure me, of checking their veracity. But who says that what people tell us about themselves reveals actual emotions and motivations?
This may be true for simple attitudes free from moralizations ("What is your favorite music?"), but it seems almost pointless to ask people about their love life, eating habits, or treatment of others ("Are you pleasant to work with?"). It is far too easy to invent post hoc reasons for one's behavior, to be silent about one's sexual habits, to downplay excessive eating or drinking, or to present oneself as more admirable than one really is. No one is going to admit to murderous thoughts, stinginess, or being a jerk. People lie all the time, so why would they stop in front of a psychologist who writes down everything they say? In one study, female college students reported more sex partners when they were hooked up to a fake lie-detector machine than without it, thus demonstrating that they had been lying before.5 I am in fact relieved to work with subjects that don't talk. I don't need to worry about the truth of their utterances. Instead of asking them how often they engage in sex, I just count the occasions. I am perfectly happy being an animal watcher.
Now that I think of it, my distrust of language goes even deeper, because I am also unconvinced of its role in the thinking process. I am not sure that I think in words, and I never seem to hear any inner voices. This caused a bit of an embarrassment once at a meeting about the evolution of conscience, when fellow scholars kept referring to an inner voice that tells us what is right and wrong. I am sorry, I said, but I never hear such voices. Am I a man without a conscience, or do I—as the American animal expert Temple Grandin once famously said about herself—think in pictures? Moreover, which language are we talking about? Speaking two languages at home and a third one at work, my thinking must be awfully muddled. Yet I have never noticed any effect, despite the widespread assumption that language is at the root of human thought. In his 1973 presidential address to the American Philosophical Association, tellingly entitled "Thoughtless Brutes," the American philosopher Norman Malcolm stated that "the relationship between language and thought must be so close that it is really senseless to conjecture that people may not have thoughts, and also senseless to conjecture that animals may have thoughts."6
Since we routinely express ideas and feelings in language, we may be forgiven for assigning a role to it, but isn't it remarkable how often we struggle to find our words? It's not that we don't know what we thought or felt, but we just can't put our verbal finger on it. This would of course be wholly unnecessary if thoughts and feelings were linguistic products to begin with. In that case, we'd expect a waterfall of words! It is now widely accepted that, even though language assists human thinking by providing categories and concepts, it is not the stuff of thought. We don't actually need language in order to think. The Swiss pioneer of cognitive development, Jean Piaget, most certainly was not ready to deny thought to preverbal children, which is why he declared cognition to be independent of language. With animals, the situation is similar. As the chief architect of the modern concept of mind, the American philosopher Jerry Fodor, put it: "The obvious (and I should have thought sufficient) refutation of the claim that natural languages are the medium of thought is that there are non-verbal organisms that think."7
What irony: we have traveled all the way from the absence of language as an argument against thought in other species to the position that the manifest thinking by nonlinguistic creatures argues against the importance of language. While I won't complain about this turn of events, it owes a great debt to language studies on animals such as Alex: not so much because these studies demonstrated language per se but because they helped expose animal thought in a format that we easily relate to. We see a sharp-looking bird, who replies when spoken to, pronouncing object names with great accuracy. He faces a tray full of objects, some made of wool, some of wood, some of plastic, representing all colors of the rainbow. He is invited to feel every object with his beak and tongue, and then, after they have all been returned to the tray, he is asked what the two-cornered blue object is made of. By correctly answering "wool," he combines his knowledge of color, shape, and material with his memory of what this particular item felt like. Or he sees two keys, one made of green plastic, the other of metal, and is asked "what is different?" He says "color." Asked "which color bigger," he answers "green."8
Anyone watching Alex perform, as I did in the early stages of his career, is blown away. Obviously, skeptics tried to ascribe his skills to rote learning, but since the stimuli changed all the time as did the questions asked, it is hard to see how he could have performed at this level based on stock answers. He would have needed a gigantic memory to handle all possibilities, so much so that it is in fact simpler to assume, as Irene did, that he had acquired a few basic concepts and was capable of mentally combining them. Furthermore, he didn't need Irene's presence to answer, nor did he even need to see the actual items. In the absence of any corn, he might be asked what color corn is and would say "yellow." Particularly impressive was Alex's ability to distinguish "same" from "different," which required him to compare objects on a variety of dimensions. All these capacities—labeling, comparing, and judging color, shape, and material—were assumed to require language at the time that Alex began his training. It was an aggravating struggle for Irene to convince the world of his skills, especially since skepticism with respect to birds ran so much deeper than it ever was for our close relatives, the primates. After years of persistence and solid data, however, she had the satisfaction of seeing Alex turn into a celebrity. Upon his death in 2007, he was honored with obituaries in both The New York Times and The Economist.
In the meantime some of his relatives had begun to impress as well. Another African gray not only mimicked sounds but added accompanying body movements. He'd say "Ciao" while waving goodbye with a foot or wing, or say "Look at my tongue" while sticking out his tongue, just as his owner had shown him. It remained a puzzle how a bird was able to draw such parallels between the human body and its own.9 Then there was Figaro, a Goffin's cockatoo who was seen breaking off large splinters from a wooden beam in order to rake in nuts placed outside his aviary. Before Figaro, there had been no reports of toolmaking parrots.10 It makes me wonder if Kohts ever conducted similar experiments on her cockatoo, macaw, and ara. Given her keen interest in tools and her six untranslated books, I wouldn't be surprised to hear about it one day. There is obviously still much to discover, as also became clear from tests of Alex's counting abilities.
Alex's talents were accidentally revealed while researchers were testing Griffin—a parrot named after Donald Griffin—who was staying in the same room with him. In order to see if Griffin could pair quantities with sounds, they would click twice, to which the right answer would be "two." But when Griffin failed to answer and got two more clicks, Alex, from across the room, chimed in with "four." And after two more clicks, Alex said "six," while Griffin remained mute.11 Alex was familiar with numbers and could correctly answer the question "what number is green?" after having seen a tray with many objects, including several green ones. But now he was doing addition, and more than that: he was doing it without visual input. Again, adding up numbers was once thought to be language-dependent, but this claim had already begun to wobble a few years back when a chimpanzee succeeded at it.12
Irene set out to test Alex's capacities more systematically by placing a few differently sized items (such as pasta pieces) under a cup. She'd lift the cup up for a few seconds in front of Alex, then put it down again. After this she would do the same for a second cup, then a third. The number of items under each cup was small, and sometimes there were none. After this, with only the three cups visible, Alex would be asked "how many total?" Out of ten tests, Alex mentioned the correct total eight times. The two that he missed, he got right the second time he heard the question.13 And all this in his head, because he couldn't see the actual items.
Unfortunately, this study was broken off by Alex's unexpected death. But by then this diminutive mathematical genius in a grey suit had given us ample evidence that there is more knocking around in a bird's skull than anyone had suspected. Irene concluded that "for far too long, animals in general, and birds in particular, have been denigrated and treated merely as creatures of instinct rather than as sentient beings."14
At times, Alex's talking made perfect linguistic sense. For example, once when Irene was fuming about a meeting in her department and walked to the lab with angry steps, Alex told her "Calm down!" No doubt the same expression had in the past been aimed at Alex's own excitable self. Other famous cases include Koko, the sign-language gorilla spontaneously combining the signs for "white" and "tiger" upon seeing a zebra, and Washoe, the chimpanzee pioneer of this entire field, labeling a swan a "water bird."
I am prepared to interpret this as a hint of deeper knowledge, but only after I see more evidence than we have today. It is good to keep in mind that these animals produce hundreds of signs every day and have been studied for decades. We'd need to know more about the ratio between hits and misses among the thousands of utterances recorded. How are these fortuitous combinations different from, say, Paul the octopus (nicknamed Pulpo Paul) who rose to fame after a string of correct predictions during the 2010 World Cup? In the same way that no one assumes that Paul knew much about soccer—he was just a lucky mollusk—we need to compare striking animal utterances with the probability of them coming about by chance. It is hard to evaluate linguistic skills if we never get to see the raw data, such as unedited videotapes, and hear only cherry-picked interpretations by loving caretakers. It also doesn't help that whenever apes produce wrong answers, their interpreters assume that they have a sense of humor, exclaiming "Oh, stop kidding around!" or "You funny gorilla!"15
Upon the death of Robin Williams, in 2014, when the whole country was grieving one of the world's funniest men, Koko was said to be mourning, too. It sounded plausible, especially since the Gorilla Foundation, in California, called Williams one of her "closest friends." The problem is that the two of them had met just once, thirteen years before, and that the only evidence of Koko's "somber" reaction was a photo of her sitting with her head down and eyes closed, which was hard to distinguish from a dozing ape. I found the grieving claim to be a huge stretch, not because I doubt that apes have feelings or can grieve, but because it is nearly impossible to gauge an animal's reaction to an event it has not witnessed. While it is entirely possible that Koko's mood was affected by the people around her, this is not the same as grasping what had happened to a member of our species whom she barely knew.
All responses to death and loss thus far observed in apes concern individuals who were truly close (such as mother and offspring, or lifelong friends) and whose corpses the apes were able to see and touch. Mourning triggered by the mere mention of someone's death requires a level of imagination and understanding of mortality that most of us don't assume. It is precisely because of such inflated claims that the whole field of talking apes has fallen into ill repute over the years, and why no new projects of its kind are being initiated. Those that still do exist tend to resort to feel-good stories and publicity stunts to raise funds. There is too much of this going around, and too little hard-nosed science.
You won't often hear me say something like this, but I consider us the only linguistic species. We honestly have no evidence for symbolic communication, equally rich and multifunctional as ours, outside our species. It seems to be our own magic well, something we are exceptionally good at. Other species are very capable of communicating inner processes, such as emotions and intentions, or coordinating actions and plans by means of nonverbal signals, but their communication is neither symbolized nor endlessly flexible like language. For one thing, it is almost entirely restricted to the here and now. A chimpanzee may detect another's emotions in reaction to a particular ongoing situation, but cannot communicate even the simplest information about events displaced in space and time. If I have a black eye, I can explain to you how yesterday I walked into a bar with drunken people … and so on. A chimpanzee has no way, after the fact, to explain how an injury came about. Possibly, if his assailant happens to walk by and he barks and screams at him, others will be able to deduce the connection between his behavior and the injury—apes are smart enough to put cause and effect together—but this would work only in the other's presence. If his assailant never walks by, there will be no such information transfer.
Countless theories have attempted to identify the benefits that language bestows upon our species and to explain why language may have arisen. In fact, an entire biennial international conference is devoted to exactly this topic, where speakers present more speculations and evolutionary scenarios than you can imagine.16 I myself take the rather simple view that the first and foremost advantage of language is to transmit information that transcends the here and now. There is great survival value in communication about things that are absent or events that have happened or are about to happen. You can let others know that there is a lion over the hill, or that your neighbors have picked up weapons. This is just one idea out of many, though, and it is true that modern languages are far too complex and elaborate for this limited purpose. They are sophisticated enough to express thoughts and feelings, convey knowledge, develop philosophies, and write poetry and fiction. What an incredibly rich capacity it is: one that seems entirely our own.
But as with so many larger human phenomena, once we break it down into smaller pieces, some of these pieces can be found elsewhere. It is a procedure I have applied myself in my popular books about primate politics, culture, even morality.17 Critical pieces such as power alliances (politics) and the spreading of habits (culture), as well as empathy and fairness (morality), are detectable outside our species. The same holds for capacities underlying language. Honeybees, for example, accurately signal distant nectar locations to the hive, and monkeys may utter calls in predictable sequences that resemble rudimentary syntax. The most intriguing parallel is perhaps referential signaling. Vervet monkeys on the plains of Kenya have distinct alarm calls for a leopard, eagle, or snake. These predator-specific calls constitute a life-saving communication system, because different dangers demand different responses. For example, the right response to a snake alarm is to stand upright in the tall grass and look around, which would be suicidal in case a leopard lurks in the grass.18 Instead of having special calls, some other monkey species combine the same calls in different ways under different circumstances.19
After the primate studies, the usual rippling has added birds to the list of referential signalers. Great tits, for example, have a unique call for snakes, which pose a grave threat as they slither into nests to swallow the young.20 But whereas these kinds of studies have helped raise the profile of animal communication, some serious doubts have been raised, too, and language parallels have been called a "red herring."21 Animal calls do not necessarily mean what we think they mean: a critical part of how they function is how listeners interpret them.22 On top of this, it is good to keep in mind that most animals do not learn their calls the way humans learn words. They are simply born with them. However sophisticated natural animal communication may be, it lacks the symbolic quality and open-ended syntax that lends human language its infinite versatility.
Perhaps hand gestures offer a better parallel, since in the apes they are under voluntary control and often learned. Apes move and wave their hands all the time while communicating, and they have an impressive repertoire of specific gestures such as stretching out an open hand to beg for something, or moving a whole arm over another as a sign of dominance.23 We share this behavior with them and only them: monkeys have virtually no such gestures.24 The manual signals of apes are intentional, highly flexible, and used to refine the message of communication. When a chimp holds out his hand to a friend who is eating, he is asking for a share, but when the same chimp is under attack and holds out his hand to a bystander, he is asking for protection. He may even point out his opponent by making angry slapping gestures in his direction. But although gestures are more context-dependent than other signals and greatly enrich communication, comparisons with human language remain a stretch.
Does this mean that all the attempts to find languagelike qualities in animal communication have been a waste of time, including training projects, such as those with Alex, Koko, Washoe, Kanzi, and others? After Terrace's paper, linguists eager to rid their territory of hairy or feathered "intruders" made the fruitlessness of animal research their mantra. They were so contemptuous of it that, at a 1980 conference—the title of which contained the words Clever Hans—they called for an official ban on any and all attempts to teach animals language.25 This unsuccessful move was reminiscent of nineteenth-century anti-Darwinists for whom language was the one barrier between brute and man, including the Linguistic Society of Paris, which in 1866 forbade the study of language origins.26 Such measures reflect intellectual fear rather than curiosity. What are linguists afraid of? They had better pull their heads out of the sand, because no trait, not even our beloved linguistic ability, ever comes about de novo. Nothing evolves all of a sudden, without antecedents. Every new trait taps into existing structures and processes. Thus, Wernicke's area, a part of the brain central to human speech, is recognizable in the great apes, in which it is enlarged on the left side, as it is in us.27 This obviously raises the question of what this particular brain region was doing in our ancestors before it was recruited for language. There are many such connections, including the FoxP2 gene that affects both human articulated speech and the fine motor control of birdsong.28 Science increasingly views human speech and birdsong as products of convergent evolution, given that songbirds and humans share at least fifty genes specifically related to vocal learning.29 No one serious about language evolution will ever be able to get around animal comparisons.
In the meantime, language-inspired studies have dispelled the notion that natural animal communication is purely emotional. We now have a far better grasp of how communication is geared to an audience, provides information about the environment, and relies on interpretation by those receiving the signals. Even if the connection with human language remains contentious, our appreciation of animal communication has greatly benefited from this flurry of research. As for the handful of language-trained animals, they have proven invaluable at showing what their minds are capable of. Since these animals respond to requests and prompts in a way that we find easy to interpret, the results speak to the human imagination and have been instrumental in breaking open the field of animal cognition. When Alex hears a question about the items on his tray, he inspects them carefully and comments on the one that he was asked about. We have no trouble putting ourselves into his shoes, given that we understand both the question and his answer.
I once asked Sue Savage-Rumbaugh, who worked with Kanzi, the bonobo who communicates by pressing symbols on a keyboard, "Would you say that you study language or intelligence, or is there no difference?" She replied:
There is a difference because we have apes who have no linguistic abilities in the human sense, but who do quite well on cognitive tasks such as solving a maze problem. Language skills can help elaborate and refine cognitive skills, though, because you can tell an ape who is language-trained something that he does not know. This can put a cognitive task on a whole different plane. For example, we have a computer game in which apes put three puzzle pieces together to make different portraits. After having learned this, they get four pieces presented on the screen, and the fourth piece is from a different portrait. When we first did this with Kanzi, he would take the piece of a bunny face and put it together with a piece of my face. He kept trying, but of course it wouldn't fit. Since he understands spoken language so well, I could say to him: "Kanzi, we're not making the bunny, put Sue's face together." As soon as he heard this, he stopped making the bunny, and stuck to the pieces of my face. So, the instructions had an immediate effect.30
Since Kanzi lived for years in Atlanta, I met him multiple times and was always impressed by how well he grasped spoken English. What struck me was not his self-produced utterances—which were rather basic, certainly below the level of a three-year-old child—but the way he reacted to those by the people around him. In one videotaped exchange, Sue asks him "Put the key in the refrigerator," while she wears a welding mask to prevent Clever Hans Effects. Kanzi picks up a chain of keys, opens the fridge, and puts the keys into it. Asked to give his doggy a shot, he picks up a plastic syringe and injects it into his stuffed toy dog. Kanzi's passive comprehension is greatly helped by his familiarity with a large number of items and words. This has been tested by playing spoken words to him through headphones while he sits at a table and selects a picture of the object that he hears being mentioned. But that he is excellent at word recognition still doesn't explain why Kanzi appears to understand entire sentences.
Such understanding is something I also know of my own apes despite the fact that none of them have had language training. Georgia is a naughty chimpanzee prone to furtively collecting water from the faucet so as to spray unsuspecting visitors. Once I told her, in Dutch, while pointing a finger at her, that I had seen her. Immediately, she let the water run from her mouth, apparently realizing that there was no point trying to surprise us. But how did she know what I had said? My suspicion is that many apes know a few key words and are highly sensitive to contextual information, such as our tone of voice, glances, and gestures. After all, Georgia had just collected a mouthful of water, and I was giving a range of clues, such as pointing a finger at her and calling her by name. Without necessarily following my exact words, she had the cognitive talent to piece together what I probably meant.
When apes guess correctly, we get the distinct impression that they must have understood everything we said, but their understanding may be more fragmentary. A striking illustration was given by Robert Yerkes after an interaction with Chimpita, a young male chimpanzee:
I was feeding grapes to Chimpita one day and he swallowed the seeds. I told him he must give the seeds to me, for I was afraid they might cause appendicitis, so he gave me all the seeds he had in his mouth and then picked up some from the floor with his lips and his hands. Finally, there were two left between the cage wall and the cement floor which he could not get well with either lips or fingers. I said to him "Chimpita, when I have gone you will eat those seeds." He looked at me as if he asked why I bothered him so much. Then he went into the next cage, looking at me all the while, got a little stick, and with it poked the seeds out of the crack and gave them to me.31
It is easy to think that Chimpita must have understood the whole sentence, which is why an astonished Yerkes added, "Such behavior demands careful scientific analysis." But more likely, the ape was following the scientist's body language more closely than we are used to. I regularly have this eerie impression that apes look right through me, perhaps because they are not distracted by language. By directing our attention to what others have to say, we neglect body language compared to animals, for whom it is all they have to go by. It is a skill they employ every day and have refined to the point that they read us like a book. It reminds me of a story by Oliver Sacks about a group of patients in an aphasia ward who were convulsed with laughter during a televised speech by President Ronald Reagan.32 Incapable of understanding words as such, aphasia patients follow what is being said through facial expressions and body language. They are so attentive to nonverbal cues that they cannot be lied to. Sacks concluded that the president, whose speech seemed perfectly normal to others around, so cunningly combined deceptive words and tone of voice that only the brain-damaged were able to see through it.
The immense effort to find language outside our own species has, ironically, led to a greater appreciation of how special the language capacity is. It is fed by specific learning mechanisms that allow a toddler to linguistically outpace any trained animal. It is in fact an excellent example of biologically prepared learning in our species. Yet this realization by no means invalidates the revelations we owe animal language research. That would be like throwing out the baby with the bathwater. It has given us Alex, Washoe, Kanzi, and other prodigies who have helped put animal cognition on the map. These animals convinced skeptics and the general public alike that there is much more to their behavior than rote learning. One cannot watch a parrot successfully count up items in his head and still believe that the only thing these birds are good at is parroting.
To the Dogs
Each in their own way, Irene Pepperberg and Nadia Kohts navigated treacherous waters. It would be great if everyone were open-minded and purely interested in the evidence, but science is not immune to preconceived notions and fanatically held beliefs. Anyone who forbids the study of language origins must be scared of new ideas, as must anyone whose only answer to Mendelian genetics is state persecution. Like Galileo's colleagues, who refused to peek through his telescope, humans are a strange lot. We have the power to analyze and explore the world around us, yet panic as soon as the evidence threatens to violate our expectations.
This was the situation when science got serious about animal cognition. It was an upsetting time for many. The language studies helped kill the reigning incredulity, even if for reasons other than their original intent. With the cognitive genie out of the bottle, it couldn't be pushed back in, and science began to explore animals through less language-colored glasses. We returned to the ways Kohts, Yerkes, K?hler, and others had conceived their studies, focusing on tools, knowledge of the environment, social relations, insight, foresight, and so on. Many experimental paradigms popular today in studies of cooperation, food sharing, and token exchange go back to research of one century ago.33 Of course, there remains the problem of how to work with hard-to-control creatures, such as the apes, and how to motivate them. If they haven't grown up around humans, these animals have no clue what our commands mean and don't pay as much attention to us as we'd like them to. They remain essentially wild and hard to engage. Language-trained animals have been so much easier to deal with that one wonders how we might replace them.
In most cases this is impossible, and we'll just have to learn how to test wild or semiwild creatures. But there is one exception, which is an animal intentionally bred by our species to get along with us: the dog. Not so long ago, students of animal behavior shied away from dogs precisely because they were domesticated animals, hence genetically modified and artificial. But science is coming around to the dog, recognizing its advantage for studies on intelligence. For one thing, dog researchers don't need to worry as much about safety or to lock their subjects up in cages. They don't need to feed or maintain their subjects, since they just ask people to drop by at a convenient time with their pets. They compensate the proud owners with a certificate emblazoned with the seal of their university, which confirms their pooch's genius. Most of all, investigators don't face the motivational problems found in most other animals. Dogs eagerly pay attention to us and need little encouragement to work on the tasks that we present to them. No wonder "dognition" is an up-and-coming field.34 In the meantime, we are also learning more about human perceptions of animals. Did you know, for example, that one quarter of dog owners believe their pets to be smarter than most people?35 As an added bonus, the dog is a highly empathic and social creature, so that these studies also illuminate animal emotions, an area Darwin was excited about. He often used dogs to illustrate the emotional continuity among species.
With dogs, we even have the prospect of neuroscience at a level that remains out of reach for most other animals. In our own species, we are used to fMRI scans of the brain in order to see what we are afraid of or how much we love each other. Results of these studies are common fare in the news media. Why aren't we doing the same with animals? The reason is that humans are prepared to lie still for many minutes inside a giant magnet, which is the only way to get a good image of their brains. We can ask them questions and show them videos and compare their brain's activity with its resting state. The answers are not always as informative as they are hyped to be, though, because brain imaging often amounts to what I mockingly call neurogeography. The typical outcome is a brain map with an area lighted up in yellow or red: it tells us where things happen in the brain, but rarely do we hear an explanation of what is going on and why.36
Apart from this limitation, however, the problem that has vexed science is how to gather the same information on animals. Attempts have been made with birds, but they were not awake during the scanning itself. We also have brain scans of immobilized yet awake marmosets. Put in a scanner swaddled like Mongolian babies, these tiny monkeys were exposed to various scents.37 But for larger primates, such as chimpanzees, to undergo such a procedure—even if it were at all practical, which it is not—would cause so much stress that it would keep them from paying attention to cognitive tasks. We also cannot put them under anesthesia, since this would defeat the whole purpose. The real challenge is to get fully conscious voluntary participation.
To see how this may be done, I descended one day to the basement floor of my own psychology department at Emory University to inspect the new magnet intended for human imaging. One of my colleagues had begun to exploit this fine piece of equipment to achieve a breakthrough with the one animal that can be trained to sit still. Gregory Berns, a neuroscientist, joined me in the waiting room with Eli, a large intact male dog, and Callie, a much smaller spayed female. Callie is the hero of Greg's tale, as she is his own pet, the first dog trained to lie still with her snout in a specially designed holder.
While we waited, the dogs played nicely together in the room, but when it turned into a fight in which Eli drew a drop of blood, we had to separate them. This was surely different from most human waiting rooms. For Callie, it was the eighth time she had received the muttmuffs, or foam-filled ear seals that fit like headphones over a dog's head to reduce sound, such as the buzzing of the magnet. It is an important part of the project to get the dogs used to odd noises. Strangely enough, Greg was convinced that this might work after seeing a video of the raid on Osama bin Laden's compound. SEAL Team 6 had a trained dog jump out of a helicopter with an oxygen mask on while strapped to a soldier's chest. If you can train dogs to do this, Greg thought, we certainly should be able to get them used to the magnet's noises. This, together with training them to put their heads in a chinrest, is the secret to the project's success. With lots of little chunks of hotdog, the canines are trained at home so that the chinrest in the magnet is familiar to them and they know what is expected of them.38
Callie in a magnetic resonance scanner. Dogs can be trained to sit still, which permits the study of their cognition through brain imaging, such as fMRI.
The frequent rewards pose a bit of a problem, because eating requires jaw movements, which interfere with brain imaging. Via a special dog ladder, Callie ran into the scanner and took her position waiting for the procedure. She was a bit too excited, though, because her tail wagged wildly, adding another source of body movement. Greg's joking that we were looking for the tail-wagging area in the brain was not too far off. Eli needed a bit more encouragement to enter the scanner but was convinced once he saw his familiar chinrest. His owner told me that he is so used to it, and associates it with such good times, that she sometimes finds him sleeping at home with his head inside. He remained still for three minutes, long enough for some good scanning.
Pretrained hand signals tell the dog in the scanner whether a treat is forthcoming. This is how Greg studies activation of their pleasure centers. His goals are rather modest at this point, such as to show that similar cognitive processes in humans and dogs engage similar brain areas. Greg is finding that the prospect of food activates the caudate nucleus in the canine brain in the same way that it does in the brain of businessmen anticipating a monetary bonus.39 That all mammalian brains operate in essentially the same way has also been found in other domains. Behind these similarities is a much deeper message, of course. Instead of treating mental processes as a black box, as Skinner and his followers had done, we are now prying open the box to reveal a wealth of neural homologies. These show a shared evolutionary background to mental processes and offer a powerful argument against human-animal dualism.
Although this research is still in its infancy, it promises a noninvasive neuroscience of animal cognition and emotion. I felt as if I were at the threshold of a new era, while Eli trotted out of the scanner to lean his head on my knee and let out a deep dog sigh to signal his relief that all had ended well.
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