INTRODUCTION

If a Lion Could Talk

Animal Intelligence and the Evolution of Consciousness



By STEPHEN BUDIANSKY



Free Press

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GORILLA SAVES TOT IN BROOKFIELD ZOO APE PIT ran the page-one headline of the Chicago Tribune. The story, quickly picked up around the world as television crews from Britain, Germany, Australia, and the ever-present CNN descended on the scene, was as follows: Binti, an eight-year-old female lowland gorilla and "bona fide hero" had rescued a three-year-old boy who had climbed over a railing and fallen into an enclosure with seven gorillas. The reports told how Binti picked up the unconscious boy, cradled him in her arms, and carried him gently to a door to the apes' enclosure where paramedics were waiting. "Another gorilla walked toward the boy, and she kind of turned around and walked away from the other gorillas and tried to be protective," one visitor told reporters. A keeper at another zoo who had helped raise Binti during the first month of the gorilla's life and who had watched the rescue on television said, "I could not believe how gentle she was. I just had chills."

Visitors who had read the story poured into the zoo to see Binti. Some told reporters that they had cried when they heard about the ape's marvelous feat. Others sent gift bananas or called to sign up for the zoo's "adoption" program -- a $25 or greater annual contribution to help pay for the care and feeding of the zoo animal of your choice.

Binti's saga is the prototypical animal story of our age. Stories of elephants that grieve and elephants that paint pictures, of dolphins that rescue swimmers in distress, of talking parrots that say "I love you! I'm sorry!" of gorillas that insist on watching Pavarotti on TV, of dogs that pull their owners from burning buildings -- such tales are seized on with an eagerness that transcends our mere tendency toward the sentimental. The alleged sagacity, insight, even morality or compassion of animals is taken as proof that animals do not merely know, but know better than selfish and brutal humankind.

Binti's heroic rescue is typical in another way: It is not exactly true. The widely circulated version of events omitted several crucial details. For one thing, Binti did not in fact shield the injured boy from the other gorillas. That job fell to the zoo keepers, who quickly responded (like good Southern sheriffs) by turning on three high-pressure fire hoses and training them at the other gorillas' feet. By these means the other gorillas were shooed out another door of their pen. "The media made it sound like Binti made a conscious decision to, quote unquote 'save the boy,' but this is speculation," lead keeper Craig Demitros said six months later at a workshop where zoo keepers met to discuss maternal behavior in gorillas. "She saved him from what, really? The other animals were not coming after him," he said.

The other missing detail in the story was even more telling. Many gorillas reared in zoos do not develop proper maternal behavior -- which in mammals often involves not only instinct but learning. Binti, herself neglected by her mother and hand-reared by humans, received extensive training in how to be a mother when she became pregnant. The zoo keepers trained her to carry a doll and, moreover, to retrieve it and bring it to her keepers. In other words, Binti was just doing what she had been trained to do -- no different from the way a search-and-rescue dog is trained to track a human's scent, or, for that matter, the way a retriever is trained to fetch a stick. The fact that the boy had been stunned by his fall of more than twenty feet helped, too. "If he had been awake and screaming, he might well have elicited a different kind of response," Demitros explained -- Binti might have run away, or even pushed or bitten the boy.

Those who seize on such tales as proof that animals are far more remarkable than science has given them credit for have, ironically, adopted a profoundly self-centered definition of intelligence. What invariably provokes comment is how closely the animal seems to have resembled man's capacities for thought and emotion. Tales of elephants grieving for their dead, of red foxes as doting fathers full of parental love for their cubs, of chimpanzees that silently watch sunsets -- such are the stories that animal rightists invoke in their effort to knock man off his anthropocentric pedestal at the top of creation. What makes an animal worthy of special consideration, they are effectively saying, is how closely its behavior resembles that of a human (or at least a human on a good day). In their battle against anthropocentrism they have adopted the most anthropocentric stance imaginable. It is an argument as curious as it is revealing.

If the modern sciences of evolutionary biology and ecology have taught us anything, it is that life generates diversity; the millions of species on earth each reflect millions of years of separate adaptation to unique enviromnents and unique ways of life. The mind is no exception to the facts of natural selection; it makes as little sense to expect that other species should share the uniquely human thought processes of the human mind as it would to expect that we should share an elephant's trunk or a zebra's stripes. And as we shall see, evolutionary ecology, the study of how natural selection has equipped animals to lead the lives they do, is beginning to tell us much about how the minds of animals process information in ways that are uniquely their own.





CONTINUITY AND DUALISM

How animals think, and what they think about, are ancient questions that have proved both irresistible and maddeningly elusive. Historically there have been two great currents in human thought on the subject. One emphasizes the continuity between man and other animals; the other emphasizes the discontinuities, or the duality, that separate man and the rest of creation. Both views have deep roots. Traditional tales of the North American Indians and of African tribes often eradicated the discontinuity altogether with accounts of animals that changed to humans and humans that changed to animals. The ancient Greeks, not only in their fables but in their serious philosophical ruminations, credited animals (the scheming fox, for instance) with humanlike motives and insight.

Stories of benevolent animals that warn their masters of danger appear in the folkways of virtually every human culture. The added twist in many of these stories is that the master refuses to understand what the animal has done, and in anger and misunderstanding kills the animal or allows it to die, only later to discover the truth. In A Thousand and One Nights we hear of a falcon that saved the life of the king and his horse: The king, tired from a hot day's hunt, takes a bowl carried about his falcon's neck and fills it with water he sees running down the trunk of a tree. The falcon repeatedly knocks the bowl over before the horse can drink. The king becomes angered and slices off the bird's wings with his sword, whereupon the bird lifts its head "as if to say, 'Look into the tree!'" Only then does the king see that what he took to be water running down the tree was venom being spit by an enormous snake. Essentially the same tale, with a shepherd's dog in the starring role, appears in one of Rabbi Meir's fables in the Talmud, the compilation of Jewish biblical commentaries dating from the first century. In this version the dog actually drinks the poison himself to save his master, who has ignored the dog's frantic attempts to warn him.

Traditional Western religion, however, has perhaps more frequently adopted a dualist stance. Man was instructed by no less an authority than God himself to subdue the earth, and Judaism's emphasis on man as an ethical agent, and Christianity's emphasis on the human soul (not to mention medieval Christianity's abiding distrust of vestiges of pagan animal worship), drew as sharp a line as one could possibly draw between man and non-man. Recent surveys have found that fundamentalist Christians remain among those most likely to strongly reject the notion of emotional or intellectual continuity between man and animals.

They are also the most likely to reject evolution. Darwin's theory is the scientific touchstone for champions of continuity. If man and animals have a common ancestry, if man was not the product of special creation in the image of God, then why should we not expect animals to share our fundamental capacity for rational choice, sense, reflection, insight, and feeling? Darwin's conclusion in The Descent of Man that "the difference in mind between man and the higher animal, great as it is, is certainly one of degree and not of kind" -- that "the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, etc., of which man boasts, may be found in an incipient or even sometimes in a well-developed condition, in lower animals" -- is religiously quoted by those scientists who would press to the utmost the implications of ape-language studies and anecdotes of animal creativity, insight, and deception.

But many who cite Darwin to this effect leave out Darwin's parenthetical acknowledgment of enormous practical difference between human and animal minds ("great as it is"). And elsewhere in The Descent of Man Darwin observed that "a moral being is one who is capable of reflecting on his past actions and their motives -- of approving some and disapproving of others; and the fact that man is the one being who certainly deserves this designation is the greatest of all distinctions between him and the lower animals." Aristotle called man the sole "political animal"; Darwin said man was the only moral animal or "utopian animal," in that he could modify his actions in obedience to an ideal that exists beyond any immediate, real experience.





ANTHROPOMORPHISM AND DOGOMORPHISM

This very tension between the sameness and otherness of animals may explain why we want so much to see into their mental lives. They are similar to us in so many ways and yet so different. Animals, especially the animals that so many of us share our houses and lives with, act and react in ways we find so familiar, yet they are a tantalizing closed book. The gift of human language allows us to penetrate the interior lives of our fellow men; we can read Montaigne's essays and glimpse what it was like to be a sixteenth-century French nobleman or talk to a computer programmer from Berkeley or a lama from Tibet and ask as many questions as we like about their lives, their thoughts, their feelings, their desires, their hopes, their pasts, and their futures. We do communicate with animals, but never in a way that permits them to describe their experience of being.

If our greatest obstacle to entering the mind of another animal is its inability to communicate as we do, the second greatest is our self-centered way of looking at the world. It is a fault we share with other species. It is commonplace to speak of a dog that thinks it is human, but a better statement of the situation is that the dog thinks we're dogs. Funny looking dogs, to be sure, and dogs that refuse to engage in the full array of normal dog behavior, but dogs that are enough like dogs to get along with under the working assumption they are dogs. Our dogs sniff us as they sniff other dogs, bow to us with outstretched front legs when they want to play just as they do to other dogs, and perhaps most important, submit to us as they submit to a pack leader. Cats are descendants of far less social creatures, but when they notice us at all, we're cats. They deliver dead mice to us, or beg for attention the way a kitten does from its mother with its tail straight up in the air. They paint the world in their image just as we paint it in ours. "If cattle and horses, or lions, had hands, or were able to draw with their feet and produce the works which men do," wrote Xenophanes 2,500 years ago, "horses would draw the forms of gods like horses, and cattle like cattle, and they would make the gods' bodies the same shape as their own."

So is it only natural for us to see a dog's behavior in the terms we know. When a dog defecates on the oriental rug and greets us at the door cringing, we without hesitation say he is feeling guilty over what he has done. When a horse nuzzles us, we say he likes (or even loves) us. If we are particularly competitive we say our dog or our horse loves to win blue ribbons at shows. If we are particularly given to New Age mystification, we can suggest the following explanations for why a mother lion ate her dead cub after it was killed by a male from another pride: "Maybe she felt closer to her dead offspring when it was part of her body once again. Maybe she hates waste, or cleans up all messes her cubs make, as part of her love. Maybe this is a lion funeral rite." Or maybe she was hungry.

Anthropomorphism, the tendency to view an animal's actions in terms of our own conscious intentions, thoughts, and motives, is viewed by many as an act of generosity toward the species we aim it at, and humility on our part. The ultimate compliment: You're almost human! But a more honest evaluation may be that anthropomorphism betrays an utter lack of imagination on our part -- not to mention a slavish obedience to an instinct that may well have been pounded into our genes over the course of millions of years of evolution. The eminent animal behaviorist John S. Kennedy, formerly of the University of London, has labeled our behavior "compulsive anthropomorphism," so irresistible does this tendency seem to be. Our very language almost compels us to describe phenomena in anthropomorphic terms, terms that ascribe intention and purpose even to inanimate objects. A particular plant "likes" shade. A malfunctioning engine is "giving us trouble." A computer is "trying to figure out" which printer to send a file to.

Students of evolution have long wrestled with the problem of how to avoid language that implies a purpose or goal, and by all appearances have just about given up. The "selfish gene" metaphor has wide currency: more exacting descriptions are necessarily long-winded and cumbersome. We are forever saying things like, "as the forests gave way to open grassland, horses evolved longer legs in order to run fast and escape from predators." Of course horses did nothing of the sort -- they never evolved anything "in order" to do anything. What happened was that those individual horses who, through chance mutation and recombination of genes, had longer legs were more likely to survive and pass on those genes to their offspring. But the very nature of communication always favors the succinct; there is essentially no other way of conveying the thought quickly than by invoking the metaphor of intentionality.

Man's readiness to ascribe human motives and intentions to phenomena at large is manifest in primitive peoples' view of violent weather or volcanic eruptions or earthquakes as a "punishment"; in the classical personification of Fate and Fortune and Love; and indeed in man's almost obsessive search for meaning in everyday life ("why did this tire have to go flat today!"). The most sweeping example is the nearly universal urge to believe that behind the otherwise inexplicable workings of probability is an all-knowing God who has a reason for everything that he chooses to happen to us.

Natural selection may have favored our tendency to anthropomorphize: Being able to guess at the motives of our fellow man has clear survival value. Being good at thinking "what would I do in his position" can help us calculate what our rivals may be up to and outsmart them. It can help us avoid conflict by anticipating trouble. Because evolution's relentless selection for adaptive traits has so often honed in animals instinctive behaviors that bear a strong working resemblance to the action of purposeful intent, our tendency to anthropomorphize the animals we hunt may have given us a huge advantage in anticipating their habits and their evasions. But it also has made us very bad at being objective about the true nature of the things in the world that actually are not like us.

So we are predisposed -- if not preprogrammed -- to accept tales of animals who display human motives, understanding, reason, and intentions. It takes a far greater imagination to conceive the possibility that a dog's mental life may assume a form that is simply beyond our ken.

In fact the most astonishing things (astonishing to us, that is) that animals do almost certainly have nothing whatever to do with conscious thought as we know it. A horse's or a pigeon's or a bee's ability to find its way to food or home; a monarch butterfly's ability to migrate thousands of miles with unerring accuracy; a chimney swift that catches insects with routine precision in midflight; a sheepdog that strikes the precise balance between ineffectuality and chaos to push a flock of sheep forward without them either stopping or scattering; a dressage horse that executes dozens of all but imperceptible commands -- these, after all, are the things that animals do superbly well every day of their lives. We are drawn to the coincidental oddities of animals that mimic a human mental proficiency, yet tend to ignore the prodigious feats that animal minds routinely pull off right before our eyes.





KNOWING THE OTHER

To understand what we truly can about how animal minds work inescapably means to abandon any real hope of penetrating their thoughts, or of translating their thoughts into human terms. Perhaps the oldest problem in philosophy is the question of how we can even know if mental experiences exist at all outside of ourselves. For all that any of us know, we are each the only beings in the universe capable of thinking thoughts. For how could we ever have proof to the contrary? Suppose someone demanded of you proof that you are conscious -- what could you say to convince him? No matter what your answer, he could insist that you're just a well-programmed computer, that nothing you say or do proves that there is a consciousness within. You might show him a copy of your brain scan, but he could counter that a computer has all sorts of electrical activity going inside it, too; so what?

The same problem, as it applies to computers, has tied philosophers and artificial-intelligence researchers in knots for decades. Suppose you could build a computer that completely simulated a human brain. Would it actually be conscious? Would it experience thoughts and feelings as we do? In 1950, the mathematician Alan Turing proposed a simple test: put a computer in one room, a person in the other, and ask each of them questions without peeking. If you can't tell by their answers which is which, the computer is conscious.

In our hearts we all feel there's something wrong with that definition -- that doing is not the same as understanding or consciously experiencing. I have a program on my computer called "The Talking Moose." If I haven't typed anything for ten minutes, the moose appears in the upper lefthand corner of the screen and spouts a pithy comment on life. The nice feature is that you can add your own aphorisms to his stockpile of sayings. If you just type words into its catalogue in plain English, the moose does a rather bad job at reading them; he mispronounces, puts the emphasis at the wrong places, ends his sentences dangling in the air. But a few minutes' tweaking with special code characters that control vowel sounds and intonation produces wonders; the moose can read even quite long sentences exactly the way someone who fully comprehended their meanings would. Yet no one could possibly suggest that the moose has even the most elementary understanding of the words he reads.

The philosopher John Searle made a similar point in a powerful attack he launched on the Turing test notion: suppose you put a fluent Chinese speaker in one room and in the other room you put someone who knows no Chinese but is given books listing a complete set of rules for translating and producing Chinese characters and syntax. Now send them both questions in Chinese. The results would be indistinguishable, yet no one could claim that the person following the rules has a conscious understanding of Chinese. Yet, on the other hand, this in a way was Turing's whole point: if you can't tell by outward appearances, how can you ever know?

Or maybe even our consciousness is an illusion, too; maybe everything we seem to be experiencing and thinking is not real at all; maybe we're sitting in a sensory deprivation chamber with our neurons plugged into a computer that fires off signals that create the illusion of conscious thought and experience. This is not as fanciful a point as it seems. In one experiment monkeys were first taught to recognize and respond to motion that crosses the visual field in a particular direction. When researchers then electrically stimulated a particular spot of the brain that is associated with motion sensing, the monkeys responded exactly the same as if they had actually seen the real thing.

So maybe this is your fate, too. How would you know? The experimenters get to decide each day what the computer will feed into your brain; when they're in a benevolent mood they arrange for you to think you're having a nice dinner with a $90 bottle of wine and someone else picking up the tab; when they're feeling mischievous they feed you the sensation that you're about to have to take a final exam in that German course you were sure you had dropped at the beginning of the semester.

But behind these well-worn philosophical conundrums is an arguably even greater problem we face when we try to get inside an animal's Mind. Simply stated: To truly know what a horse thinks, we'd have to be a horse -- and then we would have no way of describing horse thoughts in any way recognizable to humans. Not just because horses don't speak or write books -- but because we lack any way of expressing or even comprehending what a nonverbal thought experience is without falling back on words. Think about how hard it is to describe to someone else (or even to ourselves) the countless mental processes that our brains busy themselves with. Some are completely opaque to us. We are completely unaware of the nerve impulses that keep our heart beating. Only with a great effort are we aware of the link between our minds and the motions of our limbs. You can say to yourself, "now I'm going to lift my arm" but thinking that conscious thought is not what makes your arm go up -- try it and you'll find that you really cannot pin down what thing it is inside your head that is actually the thing that makes your arm move. Shooting a basketball while running is an extraordinarily complex computational problem that involves coordinating inputs from the eyes and legs, and outputs to the hand and arms, with a vast stored knowledge about expected trajectories; but who can describe what is going on in their minds in the process? We have all had the experience of having a thought and then struggling to find the words to express it; yet we find it nigh on impossible to describe what that preliterate thought "looked" or "felt" like. Even when we are speaking fluently, we have the sensation (if we think about it at all, which we usually do not!) of the words welling up preformed from somewhere in our brains. Not even the most ardent animal rights proponent suggests that horses or other nonhuman animals have a secret language of their own that allows them to form concepts into words. To literally see inside a horse's brain would be to enter a world that is without the words to describe it -- and so is meaningless to us.

The philosopher Ludwig Wittgenstein made the famous observation, "If a lion could talk, we would not understand him." But that begs the question: if a lion could talk, we probably could understand him. He just would not be a lion any more; or rather, his mind would no longer be a lion's mind.





THE MIDDLE GROUND OF COGNITION

It is conceivable that some day we may be able to decode enough of the "software" of the mind, piecing together clues from which neurons fire under which particular circumstances and which other neurons they connect to, to have a pretty good explanation of consciousness. But that surely will not happen any time soon. Imagine trying to figure out how The Talking Moose works by measuring the voltages in each bit of your computer's memory and processor while the moose talks. Add to the conditions of this problem that you have no clue about the machine language and logical architecture of your (or anyone else's) computer. Good luck.

It might sound like there is thus nothing left to say for the present. But there is a wonderful amount to say about animal minds, so long as we approach the matter with realism and restraint -- and respect for what animals do particularly well in the first place, rather than with a determination to make them into slightly defective versions of ourselves. The so-called cognitive revolution in psychology in the 1970s proposed that there is a great deal that animals do that perforce requires them to hold mental representations of information and to manipulate those representations, and that appropriately designed experiments can reveal something about what sort of mental events may be taking place in an animal's head -- even if we can never get at mental experiences. This view was a mighty leap from the strict behaviorist position championed by psychologists like B. F. Skinner, who insisted that all behavior was a simple, learned stimulus-response link that told nothing about the inner workings of mind -- a position that has been much vilified for reducing animals to automatons. The cognitive approach, while still drawing on an animal's manifest behavior as the chief evidence, relies on experiments that force an animal to use information not in its immediate environment to produce a choice of behaviors.

One class of fascinating experiments, for example, tests animals' abilities to form mental categories. In a typical experiment, capuchin monkeys were shown slides of persons and of "nonpersons" and were rewarded for pressing the correct button that corresponds to each category. The monkeys were then presented with a new set of person and nonperson slides to see how well they had formed a mental concept of the two categories. Such probes of an animal's mind can tell us volumes about its mental capabilities, and even give us insight into how an animal perceives its world -- at least as a practical, functional matter -- without drifting into the unknowable territory of what it experiences as it does so.

Of course realism and restraint is not what everyone is after. Many people are so emotionally committed to a belief in connecting with the mental lives of animals that they refuse to be deflected by any rational argument or prudent skepticism, or to be satisfied with anything science is likely to be able to tell us. Conjectures about the profound truths animals are trying to communicate to us about the meaning of life abound. Members of a new profession called "animal communicators" even offer to tune in to your pet's mind by telepathy and to reveal what they really think of you. Athena, a housecat, for example, reports that she loves her owner but wants to move out because of three new cats that have moved in. "She's in a constant state of stress and it's depressing her immune system," her communicator reports. Other pets dictate poetry to their owners telepathetically, we are told, and a cat at an animal refuge in New York state conceived and "communicated" the design for a new building. One communicator offers a course entitled, "What Animals Can Teach Us About Death."





THE HUMAN POLITICS OF ANIMAL CONSCIOUSNESS

The animal-rights and "deep ecology" literature is full of all sorts of similar talk about reconnecting "psychologically" and "spiritually" with animals to save the planet. But here one suspects the commitment is both emotional and political; these are the people out to knock man off his anthropocentric pedestal, after all, and what better way to do it than by setting up animals as our spiritual equals -- or betters. This line of argument has even been adopted by some animal behavior scientists, including Sue Savage-Rumbaugh, an ape-language researcher who has advanced some of the more extravagant claims for humanlike mental abilities in apes. Recently she said that those who refuse to acknowledge the near-humanness of apes have "deluded" themselves in a desperate attempt to cling to "some small measure of safety." She continued: "But at the expense of gaining some comfort, we risk alienating ourselves psychologically from all other creatures on this planet."

The political agenda behind claims for animal consciousness seems at times to have become the driving force and raison d'être for such research. "If explorations of the minds of chimpanzees and other animals do nothing more than inform the debate about the ethics of animal use research, the work will have been well worth while," wrote a reviewer of a recent book on vervet monkeys. Jane Goodall, of chimpanzee fame, wrote in the foreword to a book by animal-rights philosopher Bernard Rollin that "it is the growing moral concern for animals and their welfare among the general public that is putting pressure on scientists to investigate animal consciousness and suffering."

Indeed, Savage-Rumbaugh does not hesitate to draw political conclusions from her research: Apes should be given "semi-human legal status" she says. She also insists that shifting the moral and legal boundary we have erected between man and other animals will help eradicate the attitudes that have "led us blindly to exploit the world of nature," destroy tropical rain forests, and mistreat animals.

Other researchers accuse Savage-Rumbaugh of overinterpreting the results of her language studies; where she sees her chimpanzees creating true sentences that display an understanding of syntax and semantics (the chimps push buttons labeled with symbols that stand for various nouns and verbs), others point out the extremely rote nature of the chimps' sentences, 96 percent of which are demands for food, toys, or tickling. As one of the chief critics, Herbert Terrace, has pointed out, interpreting a sequence of four button-pushes to be the equivalent of a syntactical sentence "please machine give M&Ms;" makes no more sense than interpreting the sequence of buttons a person pushes while operating an ATM machine "as a sentence meaning, please machine give cash." This is an issue we shall return to in chapter 6.

Savage-Rumbaugh counters that if anyone is politically motivated and irrational, it is those in the scientific orthodoxy who have an "emotional" fear of upsetting man's self-appointed place at the top of the animal heap and who accordingly have ruled out any inquiry into animals' interior mental experiences -- their thoughts, feelings, and intentions. In making this charge she joins with a small but growing number of animal behaviorists who see the long-standing ban on anthropomorphism as a sort of conspiracy to disallow any evidence that might question man's special place in the world. "The concept of mind as we human beings experience it has for many people come to represent an unbreachable boundary between humans and nonhumans," she states, a boundary that "is being policed" by scientists. Others are more explicit in the conspiracy-theory charge; Donald Griffin, a Harvard researcher who is among the leaders of those decrying what he calls the "behavioristic taboo," says that animal behaviorists are "constrained by a guilty feeling that it is unscientific to study subjective feelings and conscious thoughts." He continues: "We have been so thoroughly brainwashed by the vehement rejection of suggestive evidence of animal thinking that it is considered foolhardy for students and aspiring scientists to let their thoughts stray into such forbidden territory, lest they be judged uncritical or even ostracized from the scientific community."

Imputing humanlike feelings and consciousness to animals is merely self-evident common sense that ordinary people have known all along, the conspiracy theorists argue; scientists who reject this view are just following the intellectual fashion of behaviorism, which, at least in caricature, posits that animals are nothing but stimulus-response machines incapable of even having mental states.

Most animal rightists trace the conspiracy back to Descartes, the great seventeenth-century champion of dualism, who, we are told, argued that animals truly were automatons, clockwork machines that lacked a mind altogether. But that view of clockwork, machinelike animals has been rejected by modern cognitive scientists, and indeed it is something of a caricature of even Descartes' views. Descartes' dualism was not so much a distinction between animals and man as between body and soul. The soul -- possessed uniquely by man -- was to Descartes a matter beyond scientific scrutiny, but the body -- possessed by both man and animals -- was fair game for science.

Even as they reject Cartesian dualism, though, modern cognitive scientists for the most part remain furious critics of anthropomorphism. Even the early twentieth-century behaviorists were not so much waging a philosophical war against the notion of continuity as they were waging a methodological war against the fuzzy thinking of "mentalism" -- the uncritical late-nineteenth-century effort to impute conscious reasoning powers to animals. While mentalism perforce implies continuity, the opposite statement -- that behaviorism implies dualism -- does not hold at all. The behaviorists were not saying that animals do not have mental experiences, only that it is impossible for us to know. Given the repeated, and in retrospect often foolish mistakes made by researchers who enthusiastically mistook rote learning in animals as feats of conscious reasoning, this was a prudent course of action.

The behaviorists' fundamentally skeptical stance was well summarized by Edward L. Thorndike, one of the first true experimental psychologists who, in the early years of the twentieth century, noted that most books on animal behavior

do not give us a psychology, but rather a eulogy, of animals. They have all been about animal intelligence, never about animal stupidity....The history of books on animals' minds thus furnishes an illustration of the well-nigh universal tendency in human nature to find the marvelous wherever it can. We wonder that the stars are so big and so far apart, that the microbes are so small and so thick together, and for much the same reason wonder at the things animals do. Now imagine an astronomer tremendously eager to prove the stars as big as possible, or a bacteriologist whose great scientific desire is to demonstrate the microbes to be very, very little! Yet there has been a similar eagerness on the part of many recent writers on animal psychology to praise the abilities of animals. It cannot help leading to partiality in deductions from facts and more especially in the choice of facts for investigation. How can scientists who write like lawyers, defending animals against the charge of having no power of rationality, be at the same time impartial judges on the bench?

The only behaviorists who insist that the methodological decision to study only overt behavior actually reflects an underlying psychological reality -- that is, that not only must we study animals as if they were stimulus-response machines, but they actually are stimulus-response machines -- are the so-called radical behaviorists. Yet theirs is actually the ultimate continuity stance, for radical behaviorists argue that even human thoughts are nothing but conditioned responses -- that is, that thinking actually consists of behavior, and that consciousness in truth does not exist. Or, as the psychologist Jeffrey Gray put it, "One is tempted to add: it is 'just a figment of our imagination.'" Gray also reported that he once asked a radical behaviorist what the difference would be between two awake individuals, one of them stone deaf, who are both sitting immobile in a room listening to a recording of a Mozart string quartet. The radical behaviorist answered: their subsequent verbal behavior.

One of the themes we shall return to is that between the annihilation of thought by the radical behaviorists and the elevation of thought to the level of human consciousness by nineteenth-century mentalists and modern "cognitive ethologists" like Griffin, lies a rich world of possibility. Modern cognitive science and evolutionary ecology are beginning to show that thinking in animals can be complex and wonderful in its variety, even as it differs profoundly from that of man.





I OPEN LATCHES, THEREFORE I AM

The historical roots of the modern distrust of anthropomorphism are worth a closer look, for the charge that it is all a "taboo" or irrational prejudice has tended to stick in recent years.

In the second half of the nineteenth century a number of writers, spurred on by Darwin's theory of evolution, began enthusiastically recounting tales of the power of reason displayed by animals -- mainly clever dogs and other household pets. One of the greatest collectors of clever dog stories in support of Darwinian continuity was George Romanes, a friend and supporter of Darwin's. His book Animal Intelligence is crammed with anecdotes of dogs and cats that open latches and doors, that trick their owners with clever deceptions, and so on. But what distinguishes Romanes' writing is not so much the anecdotal nature of these illustrations as his enthusiasm for interpreting every feat of cleverness in terms of conscious reasoning -- which he defined as an ability to perceive ratios or analogies, draw inferences, or predict probabilities. "We can only conclude," he wrote of latch-opening cats, "that the cats in such cases have a very definitive idea as to the mechanical properties of a door, they know that to make it open, even when it is unlatched, it requires to be pushed...she must reason, 'if a hand can do it, why not a paw?'"

Romanes' operating assumption was that "whenever we see a living organism apparently exerting an intentional choice, we may infer that it is a conscious choice." For example, he describes a fox caught by a farmer in a henhouse; the fox collapses on the floor and plays dead; the farmer chucks the seemingly lifeless body out the door; whereupon the fox gets up and runs away. Romanes concludes: "It seems to me that the probability rather inclines to the shamming dead having been due to an intelligent purpose."

Romanes acknowledged that to interpret an animal's thought processes this way required a heavy dose of inference from our own mental patterns, which we access through introspection. But Romanes invoked continuity to defend this process, which he termed an "ejective" method of inquiry, neither subjective nor objective, that permitted us to project our "own subjectivity" onto "the otherwise blank screen of another mind." He said a skeptic would be logically bound to deny evidence of mind in any organism, even in humans other than the skeptic himself.

Lloyd Morgan, another nineteenth-century pioneer of animal behavior study, agreed that introspection was the only source we have for "direct and immediate acquaintance" with psychological processes. But he also warned that applying our introspective knowledge to other animals was a "doubly inductive" process, and he was highly critical of wanton claims of reasoning in animals on the basis of feats that could be explained through simple learning alone, what Morgan called "sense-experience." He used his own anecdotes to show how easily we are misled, both by the very anecdotal nature of all of these stories and by our ready anthropomorphic projections onto the mental processes of the animals involved. He described his own Scotch terrier pup's struggles with carrying a cane through a gate. The dog had learned to carry the cane happily whenever he went for a walk, grasping it in the middle so it balanced comfortably. The first time they came to a gate, the dog dropped the cane and went on through. When sent back to fetch it, the dog seized the cane by its end and dragged it through. If the tale had stopped there, it would have been a perfect clever dog story: the animal had reasoned that the gate was too narrow for the cane to pass through if he held it by the middle, so he invented on the spot a novel strategy to cope with the situation.

But the tale didn't end there, for as Morgan was returning home with his dog along the same path, the animal did not drop the stick when they came to the gate, but rather repeatedly tried to smash through the gate holding the stick in the middle, each time striking the gate posts. Morgan then tried some more deliberate experiments, trying to teach a dog how to pull a crooked stick through a fence with narrow vertical rails. Morgan spent half an hour trying to show the dog how easy it was to pull the stick through, but each time the dog would try to yank it straight through and the crook would catch. Finally the dog seized the crook and as chance would have it broke it off. A passing man who saw only this end result stopped and observed to Morgan: "Clever dog that, sir; he knows where the hitch do lie."

As for the much-commented-on latch-opening abilities of animals, Morgan noted that a Scotch staghound that had learned to open a door into the yard performed the feat each time in precisely the same fashion: he would jump up on the door and scratch violently from the top downward over the entire area of the door, until at some point or other he finally struck the latch and the door opened. The dog had obviously done this once and it had worked, and then had stuck with a proven formula, a formula that betrayed not the slightest grasp of the underlying principle of the latch.

Morgan was careful to emphasize that he was not adopting what he called "the false position of dogmatic denial of rational powers to animals." But he noted that again and again the stronger claims for reasoning by animals, made by projection of human mental experience, did not stand up to scrutiny. Animals did remarkably stupid things in situations completely analogous to situations where they had exhibited apparent insight or reasoning; they demonstrably learned some of their clever feats by pure accident; and anecdotes could never tell you what previous learning experiences an animal might have had before performing its seemingly clever feat. It was not dogma but hard experience that led him to formulate "Morgan's canon," his "basal principle" that "in no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of the exercise of one which stands lower in the psychological scale."

Edward L. Thorndike extended Morgan's criticisms. His chief point was that it was not merely unnecessary to invoke reasoning by analogy or other conscious thought processes to explain animal behavior; it could often be shown on further investigation that such explanations were actually wrong, however tempting and superficially convincing they at first seemed to be. Thorndike's method was to study how animals learned completely novel tasks under controlled conditions. In his most famous experiments, he placed cats in "puzzle boxes"; to escape, the animals had to press a lever or pull a string or sometimes perform a series of such actions. On their first try, all of his cats showed "customary instinctive clawings and squeezing and biting." In one test where cats had to press a thumb latch and push against a door to escape, eight cats did manage in the course of their (clearly random) struggles to push down the thumb piece; only six ever managed to push the thumb piece and press against the door at the same time; and of those only three, and only after repeated trials, managed to associate their actions with escape. "The great support of those who do claim for animals the ability to infer," Thorndike concluded, "has been their wonderful performances which resemble our own. These could not, they claim, have happened by accident. No animal could learn to open a latched gate by accident. The whole substance of the argument vanishes if, as a matter of fact, animals do learn those things by accident. They certainly do."





CLEVER HANS, CHIEF SPOILSPORT

There was no more dramatic illustration of the point Thorndike was making than Clever Hans, a horse who was making headlines in Berlin at almost the same time Thorndike was writing those words. Clever Hans has since become a staple cautionary tale in animal behavior research. Hans had gained his fame by solving mathematical problems -- and not just simple arithmetic, but also puzzles such as adding 25 to 15 or finding the factors of 28. Hans could also tell time, identify musical scores, and answer questions about European politics. He would count out the answers to the math problems with his foot and answer "yes" or "no" to other sorts of problems by nodding or shaking his head. His owner, an elderly schoolmaster named Wilhelm von Osten, had patiently taught Hans his lessons, rewarding him with a sugar cube when he got the right answer. Von Osten was no perpetrator of hoaxes but an honest man who firmly believed in his horse's mastery of his subjects.

Von Osten was hardly the only believer. As one psychologist noted at the time, many zoologists saw in Hans's abilities confirmation of the essential similarity between human and animal minds, a doctrine that "has been coming more and more into favor since the time of Darwin."

At last, an investigation by the Prussian Academy of Sciences got to the bottom of Hans's remarkable talents. Remarkable they were, but not in the way anyone had believed. The key finding was that Hans could not answer questions correctly when no one in the room with him knew the correct answer -- for example, when two people separately whispered numbers to Hans for him to add together, but did not tell each other their numbers until after Hans had had his chance to answer. What was happening was this: Unconsciously, Hans's questioners were cueing the horse, for example by subtly bobbing their heads in anticipation of the correct answer, or tensing up as Hans counted and then subtly relaxing when he got to the right number. People who knew the right answer ahead of time were naturally anxious to see if Hans would get it right, and were betraying some sign of acknowledgment, unconscious even to themselves but not to Hans, when he did.

Horses, as social, herd-dwelling animals adapted to an open environment, have a remarkable evolved ability to pick up on subtle visual cues from their fellows. Hans was undoubtedly "clever" in that regard. He was able to form a myriad of very subtly linked associations through learning. He had discovered that if he stopped pawing just when the appropriate cue appeared, he would get a sugar cube. But he did not in fact "know" a thing about square roots, the kings of Spain, or Beethoven.

The lesson was -- or should have been -- simple: We are easily fooled by animals' ability to learn from inadvertent cues. We are especially easily fooled when that learning takes a form that, on the surface, appears identical to things that people do.

Neo-mentalists such as Savage-Rumbaugh indignantly complain that the story of Clever Hans has become part of the conspiracy to rob animals of their due. James Gould, a protégé of Donald Griffin's, has said that "once the Clever Hans story began circulating, any suggestion that animals had any native intelligence was in trouble. Behaviorists began using the incident as proof that everything nonhuman creatures do is simply the result of instincts programmed into them from birth." But this is an odd complaint. No scientists ever suggested that Clever Hans hadn't learned, or that he was merely following preprogrammed insticts. He certainly had learned. He just hadn't learned what the quick-to-anthropomorphize humans thought he had learned.

In the Clever Hans episode, anthropomorphism wasn't so much the original sin as the cover-up for the sin. The original sin was an experimental method that permitted inadvertent cueing; what anthropomorphism did was to provide a superficially convincing explanation that could cover a multitude of such sins. The reason that most behavioral researchers reject anthropomorphism is precisely because it offers a pat explanation that lets researchers off the hook from probing deeper for alternative explanations or confounding variables. Imputing reason and understanding seemed to explain Clever Hans's behavior perfectly; why look further?

Inadvertent cueing is just one of many confounding factors that further investigation has shown up. A related factor that bedevils many experiments (including, as we shall see, many experiments specifically designed to probe cognitive processes) is imprecise experimental design. The experiment mentioned at the beginning of this chapter, in which capuchin monkeys were tested for their ability to categorize "person" and "nonperson," is a good case in point. The initial results seemed very promising; the monkeys were able to correctly categorize 75 percent of the novel slides they were shown. But, ever mindful of Clever Hans, the researchers realized from the start that there was simply no guarantee that an animal's seemingly correct performance was controlled by the same categories conceived of and perceived by their human experimenters. The experimenters tried to control for as many inadvertent cues as they could think of. Maybe the monkeys weren't responding to the image in the picture at all, but to its overall brightness. Maybe there were objects in the background of the photos that the monkeys had picked out to form their "categories." It was precisely those doubts that led the experimenters to press on even after obtaining their strongly positive results. And what they found was a classic Clever Hans phenomenon: a subsequent analysis of the mistakes the monkeys made revealed something very funny. A significant proportion of the slides incorrectly categorized by the monkeys as a "person" had a patch of red somewhere in the image. And the nonperson slides most likely to be misidentified as a person had that patch of red as a feature of an animal or a flower. In other words, the monkeys seemed not to be using the experimenters' categories at all, or at the very least they were categorizing the images on a different set of criteria from what the humans who designed the test imagined.

Another confounding variable that anthropomorphic interpretation can disguise is previous learning or experience. This proved to be the case with Wolfgang Köhler's famous experiments with chimpanzees in the 1910s. Köhler noted that in Thorndike's puzzle box experiments, the animals were forced by the design of the escape mechanisms to resort to trial and error, as the mechanism itself was hidden. Köhler decided to present animals with problems where the solution was in plain view, to see whether they were capable of working out the solution by insight rather than chance. In one test, for example, food was placed outside of a barred cage, out of reach of the chimpanzee within. The chimpanzee was supplied with a stick, however, that could be used as a rake to pull the food within reach. In a more difficult variation, the food could be raked in only if two sticks, which could be fitted together end to end, were used. Köhler concluded that some of his chimpanzees did indeed use insight to solve this problem. The difference between Thorndike's and Köhler's animals led Bertrand Russell to wryly comment that "All of the animals that have been carefully observed...have all displayed the national characteristics of the observer. Animals studied by Americans rush about frantically, with an incredible display of hustle and pep, and at last achieve the desired result by chance. Animals observed by Germans sit stiff and think, and at last evolve the solution out of their inner consciousness."

But it has since become apparent that Köhler's Germanic chimps did not evolve the solution out of their inner consciousness. Chimpanzees that have never had the chance to play with sticks fail to use the sticks as rakes in such experiments. And chimpanzees supplied with sticks even when there was no problem to solve immediately began playing with them; such "irrelevant" behavior is extremely common in apes. (In one experiment, forty-eight chimpanzees were given sticks that could be fitted together; within an hour thirty-two of them had done so.) It was only by first having had such a chance to learn, by trial and error, what a stick can do that the chimpanzees were able to use them to solve problems. Once again, the readiness to accept insight as an explanation for animal behavior -- a very human (and not just Germanic) interpretation of events, as we know we do in fact solve problems that way -- led to experimental blindness.

Invoking chance and coincidence to explain away seemingly impressive cognitive feats by animals may seem like a cop-out criticism, a counterargument you use when you can't think of anything else. But it is absolutely relevant in the case of anecdotes -- especially anecdotes plucked out from perhaps thousands of hours of observations precisely because they seemed remarkable examples of humanlike thought or strategy or problem solving. It is not just a pedantic criticism to note that lots of things that look clever really are nothing more than chance. If you pick a winning horse at the track, you can have great fun "analyzing" for your friends the brilliant calculations you made and the expert knowledge you brought to bear on your choice, when in fact you made your selection based on the fact that the horse had the same name as your old girlfriend. And lots of people place winning bets every day.

In one much repeated anecdote, Washoe, the first chimpanzee to be "taught" sign language, was reported by her trainers to sign water plus bird when she saw a swan. It was a novel combination and seemed to show a creative insight. Maybe it did, but given the number of inane and meaningless (or excruciatingly repetitive) signs Washoe made, it is hardly surprising that one or two novel combinations should appear to make sense -- especially given the certainty that any such coincidences that did occur would be eagerly seized on and reported, while the inanities would not. As others have pointed out, too, there was both water and a bird present in Washoe's environment when she signed water bird, so there may be an even simpler explanation.

Clever Hans illustrated vividly how the very act of training an animal with the aim of demonstrating an advanced mental ability can queer the pitch. A researcher out to prove his case is terribly susceptible to betraying his desired results to his animals, who, as Clever Hans showed, are remarkably adept at producing more-than-reasonable facsimiles of an ability his trainer wishes to find. Treat your dog like a human, and he tries to be like one, precisely because you reward him with attention for his human-like behavior. If you ooh and ahh when your dog sits with rapt attention in front of the television whenever Pavarotti is on, he will easily make the association between his behavior and the reward. Some dogs are wonderfully quick to learn to throw up regularly if they have been rewarded by being fussed over when they are sick. This happens often enough that veterinarians refer to it as the "sick pet syndrome." Researchers who push mentalist explanations are understandably on edge about always having to defend themselves against this criticism, but it's not as if it is a groundless one. Those who ignore Clever Hans are doomed to have their monkeys make monkeys of them.





Chapter One

Who is the Smartest of Them All?





The question almost everyone asks when the matter of animal minds comes up is: How smart are they? It is a question that occupied early researchers, too, at the dawn of experimental comparative psychology a century ago. Because intelligence seemed to be a quantifiable, testable parameter, studying an animal's performance on problem-solving tasks seemed the most promising avenue to exploring their mental processes.

Ranking species according to their relative intelligence fit in well, too, with many popular -- though often terribly distorted -- conceptions about Darwin's theory that were current in the late nineteenth century, and which have not yet altogether vanished. One of the most enduring misperceptions about evolution is that life represents a sort of chain of progress from inferior to superior forms. A particularly muddled version of this embodies the additional notion that progress up the chain of evolutionary advancement corresponds to the steps that the most advanced forms of life (i.e., humans) follow in the course of development from infancy to adulthood. This theory that "ontogeny recapitulates phylogeny" has no credence whatsoever in modern biology. Yet it still pops up regularly, and certainly most people tend to think about evolution in these terms, as a stepladder along which species can be ranked as higher or lower.

George Romanes, the great nineteenth-century collector of animal anecdotes, constructed an elaborate chart of the relative rankings of animals' stages of "mental development" that is a paradigm of this sort of thinking. To make the picture of a stepladder of mental ranks even neater, he equated each step with a corresponding age of mental development in humans. Thus a portion of his ranking chart looked like this, with the rank number in the first column and the corresponding stage of human development in the last:

28. Indefinite morality. -- Anthropoid Apes and Dog. -- 15 months. 27. Use of tools. -- Monkeys, Cat, and Elephant. -- 12 months. 26. Understanding of mechanisms. -- Carnivores, Rodents, and Ruminants. -- 10 months. 25. Recognition of pictures, Understanding of words, Dreaming. -- Birds. -- 8 months. 24. Communication of ideas. -- Hymenoptera. [Bees, Ants] -- 5 months. 23. Recognition of persons. -- Reptiles and Cephalopods. -- 15 months. 22. Reason. -- Higher Crustaceans. -- 14 months. 21. Association by similarity. -- Fish. -- 14 weeks. 18. Primary instincts. -- Larvae of Insects. -- 3 weeks. 17. Memory. -- Echinodermata [Starfish, etc.] -- 1 weeks. 7. Non-nervous adjustments. -- Unicellular organisms. -- Embryo. 3. Protoplasmic movements. -- Protoplasmic organisms. -- Ovum and Spermatozoa.





ANIMAL IQ

There are two basic flaws with this approach. One is the fundamental notion that some species are more highly "evolved" than others. We might naturally think of monkeys occupying a position higher on the phylogenetic scale than cats, and cats higher than rats. Yet the fact is that primates, carnivores, and rodents all diverged from a common ancestor at the same time. They are all equally "evolved." The branching tree of evolution has not just one culmination, but millions of culminations -- represented in every living species on earth today. Each is a brilliant success at what it does. The idea that fish, now stuck at level 21, are trying with all their might to ascend to level 22 is, from an evolutionary point of view, nonsense. Fish are adapted by virtue of millions of years of evolution to their particular, special evolutionary niche. They have had just as long to evolve as we have. It is not as if they are mere instances of incomplete evolution, the culmination of which is man (or Nordic man, perhaps).

The other problem is the implicit assumption that intelligence is something that can be measured on a linear scale -- and a scale where humans equal 100. Of course, by explicitly defining his stages of mental evolution in the animal kingdom in terms of the stages of mental development in human infants, Romanes was bound to end up with a purely anthropocentric definition for his rankings of intelligence. The "Properties of Intellectual Development" he those to list (morality, use of tools, recognition of persons, etc.) all have a distinctly self-centered air about them. How would one fit the navigational abilities of pigeons or the web weaving of spiders or the nest building of bowerbirds or the food caching of nutcrackers into Romanes's scheme? One wouldn't.

Some modern attempts to define intelligence in universal terms do not fare much better. Most common definitions of intelligence emphasize flexibility, creativity, and recognition of underlying patterns and overarching concepts. Some researchers, such as Steven Pinker of M.I.T., define intelligence in a more restrictive way that would seem to rule animals out of the running altogether: Pinker says intelligence is an ability to figure out how things work in order to overcome obstacles.

But animals, which as we shall see do not show any notable ability to figure out how things truly work, nonetheless show great facility at accomplishing things by acting on information they receive from the environment. They make decisions that are flexible and often appropriate. Unconsciously operating algorithms in the animal mind (ours included) produce what we would not hesitate to call intelligence were we to see a robot do it. Coordinating the movement of four legs over uneven ground while avoiding obstacles is a sophisticated computational task. We do not normally think of such automatic tasks as part of "intelligence" but why not? From a purely computational viewpoint, the sort of unconscious thought that permits an animal to recognize a predator and take evasive action could certainly involve far more brain power than distinguishing a group of three items from a group of four items. Is the former just dumb reflex and only the latter intelligence?

Another huge problem in attempting an honest, "zero-based" assessment of animal intelligence is the bias and assumptions built into the many tests that have been devised to measure it. Intelligence tests for humans have long been criticized for being culturally biased. Many of the early IQ tests used in the United States in particular suffered from this fault; they claimed to measure "native intelligence," but included questions that really measured nothing so much as familiarity with the middle-class American culture of the middle-class American psychologists who devised the tests. For example, tests given to Army recruits in World War I featured such questions as, "Washington is to Adams as first is to..." Other questions required the examinees to draw in missing parts on a series of pictures -- a stamp on an addressed envelope, a net on a tennis court, a filament in an electric light bulb, a horn on a wind-up phonograph, a trigger on a pistol, strings on a violin. Not surprisingly, many recent immigrants to America did not score very highly on the exam and were rated as "morons" or "feebleminded." Probably not very many of them played tennis, either.

But differences between human cultures pale in comparison to differences between animal species. Animals differ in temperament, perceptual abilities, motivation, social behavior, all of which affect their performance on tests we might devise for them.





WHO'S SMARTER: THE SHEEPDOG OR THE SHEEP?

Sheep have a reputation for being dumb. Border collies have a reputation for being smart. But both of these impressions may say more about our underlying prejudice than their underlying intelligence.

Much of what impresses us about dogs, after all, is their obedience to us. To put it in a slightly cynical fashion, we say a dog or a horse is smart when it does what we want it to. But many disobedient dogs or horses -- the ones we curse as stupid -- are actually every bit as clever as the "smart" ones. As quickly as the smart ones learn obedience the stupid ones learn evasions. We tend to be impressed by a dog that learns to run around behind a flock of sheep and instantly lie down on command. We are totally unimpressed by a dog that has gone to six weeks of obedience school only to begin selectively ignoring the command "here" whenever he is busy sniffing and digging and urinating in the neighbor's yard. But in both cases the underlying "intelligence" is arguably the same. In fact, from a formal learning point of view, the latter could even be seen as a superior feat -- for the dog has learned a conditionality task here: Come when called, except when you're far away and the immediate rewards of ignoring the command are greater than obeying.

Disobedient horses have likewise often mastered a sophisticated learned association -- just not the one we're trying to teach them. A disruptive horse whose antics scare its rider and cause him to end the lesson and take the horse back to the barn has cleverly learned to associate wild behavior on its part with the immediate reward of not having to work anymore. From our point of view, the horse is unteachable; in fact it is a very good learner.

The difference between the "smart dogs" and "dumb dogs" is thus largely a matter of differing temperaments -- and an artifact of our self-serving definition of intelligence in dogs. Dogs that exhibit dominant behavior are not teachable because they resist our authority. Horses that are too timid or fearful are not teachable because they tend to react emotionally and seek to escape altogether from situations when they are corrected. If most dogs and horses are teachable, that is largely because they are highly social animals, attuned to vocal and physical signals of dominance and submission; they both have a natural instinct to defer to the will of a pack or herd leader. Few of the things we ask them to do go completely or even partially against their natural propensities. Dogs in general can be house-trained because they are den-dwelling animals that have a strong instinct to keep their own nest clean. They can be taught to "shake hands" because raising a paw in that fashion is a natural submissive gesture. Border collies can be taught to herd sheep because they have been selected for generations to emphasize the part of the natural hunting instinct of wolves that involves circling and cutting off fleeing prey. People often remark how smart a Border collie is not to attack and eat the sheep -- how this goes against its natural instinct. It does nothing of the kind. Many dogs show no interest in chasing prey at all, after all; livestock guard dogs such as Great Pyrenees and Maremmas have been bred to relate to sheep more as littermates than as prey and to behave aggressively toward intruders. Cleverness doesn't enter into it.

As for the sheep we dismiss as stupid, they are quite adept at learning and recognizing individuals by their faces; they quickly and perceptively catch on to new feeding schedules; they are good at finding holes in fences. And while people do not generally think of sheep as animals that can be taught anything, in fact farm flocks can easily be trained in a few lessons (with suitable food rewards) to come when called, and show sheep are routinely trained to walk on a lead and to stand still while a judge inspects them.

Although, like horses and dogs, they are social animals with a dominance hierarchy, sheep are very shy and fearful creatures -- a clearly adaptive trait for a small, prey animal -- and they lack the expressive repertoire of vocal and physical signals that these other species have, relying more on direct physical contact to establish and reinforce the hierarchy. All of which means that it is simply harder to teach them to learn the associations we might want to teach them. However we are setting up a false dichotomy here, for the fact is that there is not very much we want to teach sheep to do. Their temperament and size just do not lend them to the roles filled by horses and dogs (a watch sheep?) so we just do not bother training them. If a person raised a lamb in the house and could think up things to teach it, there is no particular reason to doubt that it would learn them.

It is interesting that we are ready to make allowances for cats that we won't make for sheep: Most cat owners vouch for the intelligence of their pets while conceding their untrainability. The evolutionary explanation works well here, too: Cats are not group-dwelling animals, and have had no need in their evolutionary history to develop the complex system of dominance and submission that, together with subtle threats and appeasement gestures, serves so well to keep the peace in a large group. The role we can take on as pack leader or herd leader in persuading a dog or a horse to give in to our will without a fight does not exist in the cat's ecological niche.

In fables and legends, humans have tended to rate as intelligent those animals that simply have a keen visual sense (the wise owl) and dexterous hands (foxes, monkeys). Even most of the "scientific" rankings of intelligence that have been attempted largely appear to be nothing more than a rank order of visual acuity. We are visual animals ourselves, and animals that can see what we see seem smart; those that rely more on their sense of smell or hearing are the ones we tend to think of as dim bulbs. Horses tend to shy a lot because the construction of their eyes is optimized for a near 360-degree field of view, useful for spotting danger, but the price the horse pays for that is relatively poor acuity and some out-of-focus spots that can cause objects within the field of view to suddenly sail into sharp focus. "You stupid horse," we say when the animal suddenly jumps at the sight of a mailbox that it seemed to have been looking at for some time; "you horse lacking the acuity typical of the human visual system" would be a more just epithet.

Our bias in favor of animals that can see and do things is a very fundamental point we have to face up to in trying to assess relative intelligence. "If a goldfish was as intelligent as a chimpanzee, how would it show it?" asks psychologist Euan Macphail of York University in England. "A goldfish doesn't have any limbs, it doesn't have a very good visual system. When we set it a learning task, though, it learns perfectly efficiently." An animal's input and output devices, in other words, inevitably affect our impression of the power of the central processor. If there is such a thing, as general intelligence or (say) general decision-making ability, it still can only work on the inputs it receives and can only show itself through the outputs that reach the world at large. Macphail's point is that the reason monkeys and apes use tools may be nothing more complex than that they have hands. You might have the latest computer that can run an action game with elaborate 3-D full-motion color video, but if you hook it up to a monochrome monitor and a paper-tape reader, you would never know it.

The long obsession with brain size as an indicator of animal -- and human -- intelligence reflects the belief that intelligence is some general-purpose "stuff" that an individual organism is endowed with more or less of. Correlation between intelligence and brain size has been soundly rebuffed in humans, and ought pretty obviously to be equally insignificant a factor in animals; both from individual human to individual human and species to species, the factor that has by far the strongest correlation to brain size is body size. Nobody would seriously argue that tall men are smarter than short men, or that elephants are several times smarter than dogs because their brains are several times larger. One simple reason brain size grows with body size is that a larger animal has more sensory nerve fibers coming into the brain from all over its larger body, and more nerve fibers leaving the brain to control the muscles. Another point to recognize is that as brains get larger, they do not even necessarily increase their number of nerve cells in proportion. As the distance between nerve cells grows, so does the thickness of the "wires" that connect them. If they didn't, the nerve signals would attenuate too much by the time they had traversed this greater distance. So more of the space in bigger brains is taken up with the "wiring," and to a first approximation, the number of nerve cells is actually independent of total brain size. Bigger brains are simply less dense.

Of course that is not the entire story; differences in brain structure and organization do begin to appear when you start comparing reptiles and birds or monkeys and cats, or people and chimpanzees. Horses, carnivores, monkeys, apes, and man all have brains that fall significantly above the body-size/brain-size curve. (Humans have brains three times as large as a proportion of body weight as do other primates.) The major difference, though, is the increased size of the neocortex in monkeys, apes, and man. This sheet of nerve tissue, which wraps around the brain of mammals, is the so-called gray matter, and plays the lead role in processing information from the sense organs and in controlling the movement of the limbs. In hedgehogs, the neocortex accounts for less than 30 percent of the brain's total volume; in monkeys it is about 70 percent, in chimpanzees 75 percent, and in humans 80 percent. If the cortex were just a flat piece of newspaper wrapping a grapefruit, its total volume would increase more slowly than the grapefruit as a whole with increasing grapefruit size. Instead, the cortex gets increasingly wrinkled so its total surface area increases dramatically. Flatten out the cortex of a human, William Calvin notes, and it would cover four sheets of typing paper. A chimpanzee's would cover one sheet, a monkeys would cover a postcard, a rat's a postage stamp.

Neurological studies have found that different areas of the neocortex are devoted generally to different functions and there is a dramatic correlation between the size of each area devoted to each sense organ and the importance of that sense to the animal. Monkeys, diurnal animals that have a high visual acuity -- necessary for finding food and for moving through the trees without bumping into things or missing one's hold on a branch -- have a large visual area of the neocortex. Cats, nocturnal animals that rely heavily on hearing to find prey, have a correspondingly large auditory area. The touch and motor-control regions of the neocortex in humans have very large areas devoted to touch and motor control of the hands and fingers; New World monkeys have correspondingly large areas devoted to the end of the tail, which they use for grasping. Although birds lack a neocortex, their brains possess corresponding structures that appear to fill the same roles that the neocortex does in mammals.

Other parts of the neocortex appear to be involved in learning; even these "association areas" of the mammalian cortex appear to have their specialties. If one part of a monkey's neocortex is removed, it has difficulty learning visual tasks, such as which of two containers is the one with food; other parts affect its ability to learn to discriminate by sound or by touch.





ARE INPUT AND OUTPUT PART OF INTELLIGENCE?

Reptiles and amphibians clearly can learn (even worms can!), and attempts to show that a bigger neocortex or a bigger association area is correlated with greater learning ability or greater general intelligence have proved to be anything but straightforward. There are two closely related problems we encounter here -- one methodological, the other philosophical. The philosophical problem is that, as we have seen, we lack a good definition of intelligence. The traditional views on the subject, while disagreeing on many things, generally take as a common starting point that intelligence is what the brain does when it is stripped to the core. Control for the fact that animals have different sensing and manipulative abilities, and beneath it all is that general-purpose calculating and learning machine where intelligence resides. It seems natural that some animals have bigger and faster machines than others. And it also has been assumed that the basic workings of these machines all take the same form. If intelligence is a matter of general intelligence, then general problem solving and learning ability ought to be equally applicable to all problems. Thus comparative psychologists have traditionally used abstract learning problems such as matching samples or learning lists as a way to probe those underlying computational abilities, without regard to the particular body packages they come in.

More recently, though, artificial-intelligence researchers have increasingly come around to the view that a crucial part of intelligence is precisely those "peripherals" that allow the brain to operate in the real world. The point is that a superfast computer with gigabytes of memory really is dumb if it can only receive inputs from paper tape and output them on a black and white text-only screen -- its intelligence is more like that of an idiot savant than a normal human, great at solving abstract problems (like chess) but rotten at having the more general awareness of the world, and ability to relate to real problems in the real world, that (so far, anyway) differentiate a robot from a person. The ability to do things in the real world depends on the ability to receive accurate and complete data and to be able to respond in an effective way.

This view leads to a conclusion that corresponds well with "common sense" judgments we make about the relative intelligence of animals. The fact that an ape has hands and can control them really does, after all, permit it to tackle problems that a goldfish cannot. But the reason a chimpanzee is good at using tools may have far less to do with any innate superiority in its core, information-processing ability than with the fact it has hands and the machinery to run them. "We don't have any reason to suppose that if dogs had hands they wouldn't use them," says Evan Macphail.

Part of what we take for intelligence, in other words, rests in the sense and motor organs and in the wiring that controls them. The neocortex is more than just a passive mechanical linkage between the sense organs and the real brains of the operation in the central processor. In this view, intelligence is the sum total of the processor plus the peripherals. If by intelligence we mean the ability to formulate effective solutions to variable environmental challenges, then this is clearly a correct view. By way of analogy, consider the challenge a foxhound pack faces. A fox leaves a meandering and highly variable scent trail. The pack spreads out across the territory, casting for a scent; when one hound finds the scent it barks, and the other hounds respond by racing to that spot and focusing their efforts in that area. This process is continually repeated to follow the fox's trail. The pack together is far more effective than a single hound would be in solving this problem, precisely because of the addition of many extra noses and a communication system that directs where those noses should be brought to bear. If you added only extra foxhound brains, you would not noticeably increase the "intelligence" of this distributed system. It is by hooking up extra peripheral devices that the network gets smarter.

The methodological problem is that whatever stance we take on what intelligence is, it is extremely hard in practice to separate out the processor from the peripherals experimentally. Whether you call it perception or whether you call it part of intelligence per se, the peripheral devices play such a large part in the performance of intelligent acts by animals that it is difficult to be sure we are comparing like with like when we try to measure the processor part of the equation. Giving a blind person a written IQ test is obviously not a very mean meaningful evaluation of his mental abilities.

Yet that is exactly what many cross-species intelligence tests have done. Monkeys, for example, were found not only to learn visual discrimination tasks but to improve over a series of such tasks -- they formed a learning set, a general concept of the problem that betokened a higher cognitive process than a simple association. Rats given the same tasks showed difficulty in mastering the problems and no ability to form a learning set. The obvious conclusion was that monkeys are smarter than rats, a conclusion that was comfortably accepted, as it fit well with our preexisting prejudices about the distribution of general intelligence in nature. But when the rat experiments were repeated, only this time the rats were given the task of discriminating different smells, they learned quickly and showed rapid improvement on subsequent problems, just as the monkeys did.

The problem of motivation is another major confounding variable. Sometimes we may think we are testing an animal's brain when we are only testing its stomach. For example, in a series of studies goldfish never learned to improve their performance when challenged with "reversal" tasks. These are experiments in which an animal is trained to pick one of two alternative stimuli (a black panel versus a white panel, say) in order to obtain a food reward; the correct answer is then switched and the subject has to relearn which one to pick. Rats quickly learned to switch their response when the previously rewarded answer no longer worked. Fish didn't. This certainly fit comfortably with everyone's sense that fish are dumber than rats. But when the experiment was repeated with a different food reward (a paste squirted into the tank right where the fish made its correct choice, as opposed to pellets dropped into the back of the tank), lo and behold the goldfish suddenly did start improving on reversal tasks. Other seemingly fundamental learning differences between fish and rodents likewise vanished when the experiments were redesigned to take into account differences in motivation.

Equalizing motivation is an almost insoluble problem for designers of experiments. Are three goldfish pellets the equivalent of one banana or fifteen bird seeds? How could we even know? We would somehow have to enter into the internal being of different animals to know for sure, and if we could do that we would not need to be devising roundabout experiments to probe their mental processes in the first place.

When we do control for all of the confounding variables that we possibly can, the striking thing about the "pure" cognitive differences that remain is how the similarities in performance between different animals given similar problems vastly outweigh the differences. To be sure, there seems to be little doubt that chimpanzees can learn new associations with a single reinforced trial, and that that is genuinely faster than other mammals or pigeons do it. Monkeys and apes also learn lists faster than pigeons do. Apes and monkeys seem to have a faster and more accurate grasp of numerosity judgments than birds do. The ability to manipulate spatial information appears to be greater in apes than in monkeys.

But again and again experiments have shown that many abilities thought the sole province of "higher" primates can be taught, with patience, to pigeons or other animals. Supposedly superior rhesus monkeys did better than the less advanced cebus monkeys in a visual learning-set problem using colored objects. Then it turned out that the cebus monkeys did better than the rhesus monkeys when gray objects were used. Rats were believed to have superior abilities to pigeons in remembering locations in a radial maze. But after relatively small changes in the procedure and the apparatus, pigeons did just as well.

If such experiments had shown, say, that monkeys can learn lists of forty-five items but pigeons can only learn two, we would probably be convinced that there are some absolute differences in mental machinery between the two species. But the absolute differences are far narrower. Pigeons appear to differ from baboons and people in the way they go about solving problems that involve matching up two images that have been rotated one from the other, but they still get the right answers. They essentially do just as well as monkeys in categorizing slides of birds or fish or other things. Euan Macphail's review of the literature led him to conclude that when it comes to the things that can be honestly called general intelligence, no convincing differences, either qualitative or quantitative, have yet been demonstrated between vertebrate species. While few cognitive researchers would go quite so far -- and in deed we will encounter a number of examples of differences in mental abilities between species that are hard to explain as anything but a fundamental difference in cognitive function -- it is striking how small those differences are, far smaller than "common sense" generally has it. Macphail has suggested that the "no-difference" stance should be taken as a "null hypothesis" in all studies of comparative intelligence; that is, it is an alternative that always has to be considered and ought to be assumed to be the case unless proven otherwise.





ECOLOGISTS VERSUS GENERALISTS

One interpretation of these findings is that intelligence fundamentally consists of specialized intelligence, and that there may not really be much of anything left in the brain even worthy of the name general intelligence. Most of the genuine differences that appear in what different species can do reflect adaptations to the special ecological requirements of each. Spiders spin webs; many birds sing their songs even if they have never heard a model; cowbirds hunt out other birds' nests to lay their eggs in; male moose knock heads with other male moose. None of these are trivial cognitive tasks; all involve decision making, or perceptual processing, or both. All reflect highly specialized adaptations to a particular environment and way of life. The very fact that so much of the brain is devoted to the processing and control of the particular sense and motor organs that are important to an animal's way of life speaks to this point.

Learning itself seems to be highly specialized, too. Animals that can learn one sort of task often cannot learn a logically identical task. The ability to learn seems less a result of general cognitive processes than specialized channels attuned to an animal's basic hard-wired behaviors. The classic demonstration of this point came in the course of Edward Thorndike's pioneering experiments in which cats had to learn to escape from boxes by pushing levers or pulling strings. In one of his variations on this theme Thorndike placed his cats in "Box Z." This consisted of a box with no levers or gizmos at all, only a door that could be opened by the experimenter. He would do so whenever the cat in the box licked or scratched itself. The cats had considerable difficulty learning this association far more than they had in learning to pull strings or press levers. Likewise it is essentially impossible to teach dogs to yawn for a food reward. Dogs can be taught to go to the left-hand box or the right-hand box to retrieve a reward depending on whether a speaker above or below the dog sounds a tone, but dogs find it extremely hard to learn whether to go or stay according to which speaker sounds a tone. Pigeons readily learn to physically flee a shock but find it extremely difficult to learn to peck a key to avoid a shock -- even though they readily learn to peck keys to obtain food. (In fact, pigeons quickly learn to peck a lighted key even without a food reward.) Rats can learn to avoid a food that causes nausea hours later but would never make an association between a key press and a punishment so long delayed. The point is that many learned responses are "prepared" or "contraprepared" by the way an animal's brain is prewired -- prewired precisely by species-specific ecological adaptations. Pecking at things is part of the basic feeding pattern of pigeons. Flight from a noxious stimulus is a basic part of most species' defensive repertoire. Animals with paws manipulate things in their environment. Learning appears less a general cognitive process that resides in some central processor than one channeled through -- and inseparable from -- the "peripheral" processing apparatus of the brain.

Macphail's notion that all animals possess an equal measure of "general intelligence" might at first blush seem to be the opposite pole from the ecological stance, which supposes that all intelligence reflects specialized adaptations to a unique environment. But the positions are far closer together than they might appear, and their apparent difference really goes back to the matter of how we define intelligence. Macphail's point is that if you strip away all perceptual and manipulative differences between species, what is left -- which is what he defines as real intelligence -- is pretty much the same across the board. The ecological stance in effect is saying that real intelligence predominantly consists precisely of all the stuff Macphail stripped away -- the species-specific wiring of the sense and motor organs to the brain -- thus the unique differences from one species to another. Some in the ecological camp have argued that even the fundamental learning processes differ from species to species and specialized task to specialized task; that there is one mechanism for learning about spatial locations of food sources and another mechanism for learning social hierarchies and so on. But the fact remains that when arbitrary learning tasks are devised in a way that is careful to avoid sensory biases, even very different animals often learn them the same way and with equal speed.

Either way, we are left with a very interesting conclusion: That all species (all birds and mammals anyway) are pretty much equally intelligent. Which species is the smartest? They all are. It is simply meaningless to ask which of the following reflects the greater intelligence: the calculations a pigeon's brain performs to find home or the calculations a wren's brain performs to determine the distance of a rival from the sound of its song or the calculations a chimpanzee's brain performs to assess which food cache it has visited in the past is the closest. Specialization means by definition that different abilities are simply not comparable. It is the classic "apples and oranges" situation; it is literally the same as asking, Which is better, a wing or an arm? Fur or hair? Two legs or four legs? Night vision or daylight vision? A short tail or a long tail? Nests or webs? Paws or hooves? Lungs or gills? The answer in every case is, of course, that it depends -- what do you want to use them for?

And Macphail's additional point is that to the extent different abilities are comparable, they appear to rely largely -- or possibly wholly -- on a common mechanism. The differences in intelligence between animals is a matter of quality, not quantity.





WHAT ABOUT US?

Are humans able to acquire language because they're smart? Or are they smart because they have been able to acquire language? One popular theory of the evolution of the human mind supposes that our specialized adaptations to the human ecological niche carried with it, almost by accident as it were, an increase in general intelligence. A neocortex that expanded to handle visual processing and the control of precise hand motions and the sequencing of complex manual tasks was a neocortex that had stuff left over to do a lot of other things, too. The fossil record of early man is a record of ever more precise hands and ever more refined tools. Two million years ago, Homo habilis was making stone scrapers and flakes, and already the apelike hand with short thumbs and curved fingers was giving way to the more modern human hand with its long, fully opposable thumb and straight, fine fingers. His brain was still half the size of a modern humans. So did the brain generally expand to meet the demands of this ecological adaptation to tool making, and is that what made us so smart?

The more provocative notion, and one that may well fit the evidence better, however, is that our general intelligence is not very different from that of any other mammal's or birds; the only thing that really distinguishes us is the species-specific adaptation of a language-acquisition device.

By all appearances, language certainly seems to be just as hard-wired an attribute in humans as navigation is in pigeons. Children do not need to be taught language; even deaf children show a spontaneous mastery of grammatical concepts. Chimpanzees can be trained to within an inch of their lives and bribed with M&Ms; to master a few dozen learned associations between symbols and things they want; humans without any formal teaching at all learn thousands of words and the rules for combining them in an infinite number of novel combinations to express ideas. In humans speech is controlled in a specialized region of the cortex called Broca's area; humans with damage to this region from an accident or stroke have difficulty talking. Understanding appears to reside in a second region, Wernicke's area. You can cut the corresponding parts out of a monkeys brain without affecting its ability to produce or respond to vocal calls.

That humans have a hard-wired sense of grammatical structure was strikingly supported by a fascinating study in which human subjects were asked to memorize unpronounceable strings of letters, like PVPXVPS and TSSXXVPS and PVV. The strings were three to eight letters in length, and subjects were given four at a time to learn.

Unbeknownst to them, however, the strings had been generated in accordance with "grammatical" rules that, as in a real language, specified how letters can be replaced with other letters in a word. A second, control group was given strings made up of the same letters of the same lengths, but the letters were strung together in a purely random order. The group that got the grammatical gobbledygook learned new sets of words at an accelerating rate that significantly outpaced the control group that had to struggle with merely random gobbledygook. Perhaps even more interesting was the fact that when the "grammatical" group was told that their strings had been generated according to rules (but not what those rules were), they were able to do a quite good job of telling grammatical words from nongrammatical words -- even as they themselves were unable to explain what had guided their choices.

When we try to zero in on the most basic nonverbal cognitive abilities of humans, we find that people do them efficiently, quickly, and in no ways strikingly different from, or better than, nonhuman primates, cats, rats, or pigeons do them. We can remember seven or so items in a list at a time; we can orient ourselves in a room or a landscape; we can tell at a glance whether one pile of M&Ms; has more than another; we can keep our feet moving the right way on uneven ground; we can tell if a rotated object matches an unrotated one; we can recognize familiar faces; we can tell any moose from any car at a glance. And so can apes and monkeys and pigeons. Given the similarities in the cognitive abilities of those very different nonhuman species, it would be a dualist stance par excellence to try to argue that humans perform these basic, nonverbal cognitive tasks in a way fundamentally different from all other animals in creation.

Language is something else entirely. It is extremely significant that when we use language to tackle problems we are slower than computers, and slower than the innate, nonverbal mental processes our brains perform effortlessly and mostly unconsciously. The basic wiring of all brains, as the early artificial intelligence researchers found to their great frustration, did not conform to that of a general-purpose digital computer that manipulates data in sequential, logical operations. But a brain plus language does -- if it is admittedly a slow and rather plodding general-purpose problem solver.

The key is that language is a system that allows ideas to be represented ad infinitum: Language automatically offers the means to represent ideas about ideas about ideas about ideas, and so on as far as we want. Language may well be the thing that makes possible the all-important leap from merely having intentions and beliefs to having intentions and beliefs about intentions and beliefs.

Language in other words is a discontinuity. The discontinuity between our minds and the minds of other animals is thus not a matter of degree or quantity -- it is not that we just have more stuff, more memory, or a faster central processor unit. It is rather a matter of quality. We have a terrific piece of software that they simply do not. The peculiar fact of this piece of software is that it is a program that allows symbols to represent and manipulate other symbols on a completely different order from what the hardware by itself does. While a pigeon has a routine that performs a specialized application, language is a routine that performs a general task.

Being able not just to think, but to think about thoughts -- to record them, reflect on them, experiment with rearranging them -- is a step of huge adaptive significance. It allowed the first linguistic hominids to imagine solutions to problems before they tried them, to speculate about the thoughts of others (and to recognize the fact that there are such things as thoughts in the first place!), to design tools, to plan hunts, to share information, to teach one another without limitation (anything you can imagine in words you can explain to someone else in words). Language is what ultimately allowed humans, and not all of those clever apes and carnivores and bees and pigeons, to develop physics and astronomy and philosophy and ethics and electronic engineering and linguistics and history and education and justice and neurophysiology.

It is tempting to see in language an explanation for consciousness, too; language provides an automatic means for representing thoughts; when we are aware of our thoughts the thing that we are aware of is thoughts expressed in language. The artificial-grammar experiment (the one with the "words" like PVPXVPS) suggests that the acquisition of language itself is mediated by unconscious processes; that unconscious bootstrap hoists language, and thus consciousness, into place.

Yet that may be a stretch. There is evidence that human infants, even before they acquire language, begin to form concepts of mental states in others (see Chapter 6). Autistic children may lack an ability to attribute thoughts to others yet have no difficulty mastering language. So while language gives us a powerful tool for representing mental states in ourselves and in others, that may not be sufficient in itself to explain consciousness. And there is the point, too, that many of the "gut feeling" thoughts and conclusions we reach about the motivations and honesty of others seem to come from a deeper, nonverbal part of our minds. Yet the tight similarity between the meta-representation inherent in language and the meta-representations that are a nece