Are We Smart Enough to Know How Smart Animals Are

by Frans de Waal

  What we have here is a most sophisticated information-processing system backed by a specialized brain that turns echoes into precise perception. Griffin had followed in the footsteps of the pioneering experimentalist Karl von Frisch, who had discovered that honeybees use a waggle dance to communicate distant food locations. Von Frisch once said, “The life of the bee is like a magic well, the more you draw from it, the more there is to draw.”5 Griffin felt the same about echolocation, seeing this capacity as yet another inexhaustible source of mystery and wonder. He called it, too, a magic well.6

  Since I work with chimpanzees, bonobos, and other primates, people usually don’t give me a hard time when I speak of cognition. After all, people are primates, too, and we process our surroundings in similar ways. With our stereoscopic vision, grasping hands, ability to climb and jump, and emotional communication via facial muscles, we inhabit the same Umwelt as other primates. Our children play on “monkey bars,” and we call imitation “aping,” precisely because we recognize these similarities. At the same time, we feel threatened by primates. We laugh hysterically at apes in movies and sitcoms, not because they are inherently funny—there are much funnier-looking animals, such as giraffes and ostriches—but because we like to keep our fellow primates at arm’s length. It is similar to how people in neighboring countries, who resemble each other most, joke about each other. The Dutch find nothing to laugh at in the Chinese or the Brazilians, but they relish a good joke about the Belgians.

  But why stop at the primates when we are considering cognition? Every species deals flexibly with the environment and develops solutions to the problems it poses. Each one does it differently. We had better use the plural to refer to their capacities, therefore, and speak of intelligences and cognitions. This will help us avoid comparing cognition on a single scale modeled after Aristotle’s scala naturae, which runs from God, the angels, and humans at the top, downward to other mammals, birds, fish, insects, and mollusks at the bottom. Comparisons up and down this vast ladder have been a popular pastime of cognitive science, but I cannot think of a single profound insight it has yielded. All it has done is make us measure animals by human standards, thus ignoring the immense variation in organisms’ Umwelten. It seems highly unfair to ask if a squirrel can count to ten if counting is not really what a squirrel’s life is about. The squirrel is very good at retrieving hidden nuts, though, and some birds are absolute experts. The Clark’s nutcracker, in the fall, stores more than twenty thousand pine nuts, in hundreds of different locations distributed over many square miles; then in winter and spring it manages to recover the majority of them.7

  That we can’t compete with squirrels and nutcrackers on this task—I even forget where I parked my car—is irrelevant, since our species does not need this kind of memory for survival the way forest animals braving a freezing winter do. We don’t need echolocation to orient ourselves in the dark; nor do we need to correct for the refraction of light between air and water as archerfish do while shooting droplets at insects above the surface. There are lots of wonderful cognitive adaptations out there that we don’t have or need. This is why ranking cognition on a single dimension is a pointless exercise. Cognitive evolution is marked by many peaks of specialization. The ecology of each species is key.

  The last century has seen ever more attempts to enter the Umwelt of other species, reflected in book titles such as The Herring Gull’s World, The Soul of the Ape, How Monkeys See the World, Inside a Dog, and Anthill, in which E. O. Wilson, in his inimitable fashion, offers an ant’s-eye view of the social life and epic battles of ants.8 Following in the footsteps of Kafka and Uexküll, we are trying to get under the skin of other species, trying to understand them on their terms. And the more we succeed, the more we discover a natural landscape dotted with magic wells.

  Six Blind Men and the Elephant

  Cognition research is more about the possible than the impossible. Nevertheless, the scala naturae view has tempted many to conclude that animals lack certain cognitive capacities. We hear abundant claims along the lines of “only humans can do this or that,” referring to anything from looking into the future (only humans think ahead) and being concerned for others (only humans care about the well-being of others) to taking a vacation (only humans know leisure time). The last claim once had me, to my own amazement, debating a philosopher in a Dutch newspaper about the difference between a tourist tanning on the beach and a napping elephant seal. The philosopher considered the two to be radically different.

  In fact, I find the best and most enduring claims about human exceptionalism to be the funny ones, such as Mark Twain’s “Man is the only animal that blushes—or needs to.” But, of course, most of these claims are deadly serious and self-congratulatory. The list goes on and on and changes every decade, yet must be treated with suspicion given how hard it is to prove a negative. The credo of experimental science remains that an absence of evidence is not evidence of absence. If we fail to find a capacity in a given species, our first thought ought to be “Did we overlook something?” And the second should be “Did our test fit the species?”

  A telling illustration involves gibbons, which were once considered backward primates. Gibbons were presented with problems that required them to choose between various cups, strings, and sticks. In test after test, these primates fared poorly compared to other species. Tool use, for example, was tested by dropping a banana outside their cage and placing a stick nearby. All they had to do to get the banana was pick up the stick to move it closer. Chimpanzees will do so without hesitation, as will many manipulative monkeys. But not gibbons. This was bizarre given that gibbons (also known as “lesser apes”) belong to the same large-brained family as humans and apes.

  The gibbon’s hand lacks a fully opposable thumb. It is suited for grasping branches rather than for picking up items from a flat surface. Only when their hand morphology was taken into account did gibbons pass certain intelligence tests. Here a comparison between the hands of a gibbon, a macaque, and a human. After Benjamin Beck (1967).

  In the 1960s an American primatologist, Benjamin Beck, took a fresh approach.9 Gibbons are exclusively arboreal. Known as brachiators, they propel themselves through trees by hanging by their arms and hands. Their hands, which have tiny thumbs and elongated fingers, are specialized for this kind of locomotion: gibbon hands act more like hooks than like the versatile grasping and feeling organs of most other primates. Beck, realizing that the gibbon’s Umwelt barely includes the ground level and that its hands make it impossible to pick up objects from a flat surface, redesigned a traditional string-pulling task. Instead of presenting strings lying on a surface, as had been done before, he elevated them to the animal’s shoulder level, making them easier to grasp. Without going into detail—the task required the animal to look carefully at how a string was attached to food—the gibbons solved all the problems quickly and efficiently, demonstrating the same intelligence as other apes. Their earlier poor performance had had more to do with the way they were tested than with their mental powers.

  Elephants are another good example. For years, scientists believed them incapable of using tools. The pachyderms failed the same out-of-reach banana test, leaving the stick alone. Their failure could not be attributed to an inability to lift objects from a flat surface, because elephants are ground dwellers and pick up items all the time, sometimes tiny ones. Researchers concluded that they just didn’t get the problem. It occurred to no one that perhaps we, the investigators, didn’t get the elephant. Like the six blind men, we keep turning around and poking the big beast, but we need to remember that, as Werner Heisenberg put it, “what we observe is not nature in itself, but nature exposed to our method of questioning.” Heisenberg, a German physicist, made this observation regarding quantum mechanics, but it holds equally true for explorations of the animal mind.

  In contrast to the primate’s hand, the elephant’s grasping organ is also its nose. Elephants use their trunks not only to reach food but a
lso to sniff and touch it. With their unparalleled sense of smell, these animals know exactly what they are going for. But picking up a stick blocks their nasal passages. Even when they bring the stick close to the food, it impedes their feeling and smelling it. It is like sending a blindfolded child out on an Easter egg hunt.

  What sort of experiment, then, would do justice to the animal’s special anatomy and abilities?

  On a visit to the National Zoo in Washington, D.C., I met Preston Foerder and Diana Reiss, who showed me what Kandula, a young elephant bull, can do when the problem is presented differently. The scientists hung fruit high up above Kandula’s enclosure, just out of his reach. They gave the elephant several sticks and a sturdy square box. Kandula ignored the sticks but, after a while, began kicking the box with his foot. He kicked it many times in a straight line until it was right underneath the fruit. He then stood on the box with his front legs, which enabled him to reach the food with his trunk. An elephant, it turns out, can use tools—if they are the right ones.

  Elephants were believed to be inept tool users based on the assumption that they should use their trunk. In a tool task that bypassed the trunk, however, Kandula had no trouble reaching green branches hanging high above his head. He went out of his way to fetch a box to stand on.

  As Kandula munched his reward, the investigators explained to me how they had varied the setup, making life more difficult for the elephant. They had put the box in a different section of the yard, out of view, so that when Kandula looked up at the tempting food, he would need to recall the solution while distancing himself from his goal to fetch the tool. Apart from a few large-brained species, such as humans, apes, and dolphins, not many animals will do this, but Kandula did it without hesitation, fetching the box from great distances.10

  Clearly, the scientists had found a species-appropriate test. In search of such methods, even something as simple as size can matter. The largest land animal cannot always be tested with human-sized tools. In one experiment researchers conducted a mirror test—to evaluate whether an animal recognizes its own reflection. They placed a mirror on the floor outside an elephant cage. Measuring only 41 by 95 inches, it was angled up so that the elephant probably mostly saw its legs moving behind two layers of bars (since the mirror doubled them). When the elephant received a body mark that was visible only with assistance of the mirror, it failed to touch it. The verdict was that the species lacked self-awareness.11

  But Joshua Plotnik, then a student of mine, modified the test. He gave elephants at the Bronx Zoo access to an eight-foot-square mirror placed directly inside their enclosure. They could feel it, smell it, and look behind it. Close-up exploration is a critical step, for apes and humans as well; that had been impossible in the earlier study. In fact, the elephants’ curiosity worried us, as the mirror was mounted on a wooden wall that was not designed to support climbing pachyderms. Elephants normally don’t stand up against structures, so having a four-ton animal lean on a flimsy wall in order to see and smell what was behind the mounted mirror scared us to death. Clearly, the animals were motivated to find out what the mirror was all about, but if the wall had collapsed, we might have ended up chasing elephants in New York traffic! Fortunately, the wall held, and the animals got used to the mirror.

  One Asian elephant, named Happy, recognized her reflection. Marked with a white cross on her forehead above her left eye, she repeatedly rubbed the mark while standing in front of the mirror. She connected her reflection with her own body.12 By now, years later, Josh has tested many more animals at Think Elephants International, in Thailand, and our conclusion holds: some Asian elephants recognize themselves in the mirror. Whether the same can be said of African elephants is hard to tell, because up to now our experiments have resulted in a lot of destroyed mirrors due to this species’ tendency to examine new items with vigorous tusk action. This makes it hard to decide between poor performance and poor equipment. Obviously, the destruction of mirrors is no reason to conclude that African elephants lack mirror self-recognition. We are just dealing with species-typical treatment of novel items.

  The challenge is to find tests that fit an animal’s temperament, interests, anatomy, and sensory capacities. Faced with negative outcomes, we need to pay close attention to differences in motivation and attention. One cannot expect a great performance on a task that fails to arouse interest. We ran into this problem while studying face recognition in chimpanzees. At the time, science had declared humans unique, since we were so much better at identifying faces than any other primate. No one seemed bothered by the fact that other primates had been tested mostly on human faces rather than those of their own kind. When I asked one of the pioneers in this field why the methodology had never moved beyond the human face, he answered that since humans differ so strikingly from one another, a primate that fails to tell members of our species apart will surely also fail at its own kind.

  But when Lisa Parr, one of my coworkers at the Yerkes National Primate Research Center in Atlanta, tested chimpanzees on photographs of their own species, she found that they excelled at it. Selecting images on a computer screen, they would see one chimpanzee portrait immediately followed by a pair of others. One portrait of the pair would be a different picture of the same individual as presented before, while the other would show a different individual. Having been trained to detect similarity (a procedure known as matching to sample), the chimpanzees had no trouble recognizing which portrait most resembled the first. The apes even detected family ties. After having seen a female portrait, they were given a choice between two juvenile faces, one of which was the offspring of the female shown before. They picked the latter based purely on physical similarity, since they did not know any of the depicted apes in real life.13 In much the same way, we can leaf through someone else’s family album and quickly notice who are blood relatives and who are in-laws. As it turns out, chimpanzee face recognition is as keen as ours. It is now widely accepted as a shared capacity, especially since it engages the same brain areas in humans and other primates.14

  In other words, what is salient to us—such as our own facial features—may not be salient to other species. Animals often know only what they need to know. The maestro of observation, Konrad Lorenz, believed that one could not investigate animals effectively without an intuitive understanding grounded in love and respect. He saw such intuitive insight as quite separate from the methodology of the natural sciences. To marry it productively with systematic research is both the challenge and the joy of studying animals. Promoting what he called the Ganzheitsbetrachtung (holistic contemplation), Lorenz urged us to grasp the whole animal before zooming in on its various parts.

  One cannot master set research tasks if one makes a single part the focus of interest. One must, rather, continuously dart from one part to another—in a way that appears extremely flighty and unscientific to some thinkers who place value on strictly logical sequences—and one’s knowledge of each of the parts must advance at the same pace.15

  The danger of ignoring this advice was amusingly illustrated when a famous study was replicated. In the study, domestic cats were placed in a small cage; they would wander about impatiently meowing—and in the process rub against the cage interior. In so doing, they accidentally moved a latch that opened a door, which allowed them to get out of the cage and eat a scrap of fish nearby. The more trials a cat performed, the quicker she’d escape. The investigators were impressed that all the tested cats showed the same stereotyped rubbing pattern, which they thought they had taught them with food rewards. First developed by Edward Thorndike in 1898, this experiment was considered proof that even seemingly intelligent behavior (such as escaping from a cage) can be fully explained by trial-and-error learning. It was a triumph of the “law of effect,” according to which behavior with pleasant consequences is likely to be repeated.16

  Edward Thorndike’s cats were considered to have proven the “law of effect.” By rubbing against a latch inside a cage, a cat could op
en a door and escape, which would gain her a fish. Decades later, however, it was shown that the cats’ behavior had nothing to do with the prospect of reward. The animals escaped just as well without the fish. The presence of friendly people was all that was needed to elicit the flank rubbing that marks all feline greeting behavior. After Thorndike (1898).

  When the American psychologists Bruce Moore and Susan Stuttard replicated this study decades later, however, they found that the cats’ behavior was nothing special. The cats performed the usual Köpfchengeben (German for “head giving”) that all felines—from house cats to tigers—use in greeting and courting. They rub their head or flank against the object of affection or, if the object of affection is inaccessible, redirect the rubbing to inanimate objects, such as the legs of a kitchen table. The investigators showed that the food reward was not needed: the only meaningful factor was the presence of friendly people. Without training, every caged cat that saw a human observer rubbed its head, flank, and tail against the latch and got out of the cage. Left alone, however, the cats were unable to escape, since they never performed any rubbing.17 Instead of a learning experiment, the classical study had been a greeting experiment! The replication was published under the telling subtitle “Tripping over the Cat.”