Are We Smart Enough to Know How Smart Animals Are

by Frans de Waal

  But we cannot exclude that the event was a fluke, never to be repeated again, or that some decisive aspect went unnoticed. The observer may also unconsciously have filled in missing details based on his or her assumptions. These issues are not easily resolved by collecting more anecdotes. “The plural of anecdote is not data,” as the saying goes. It is ironic, therefore, that when it was his own turn to find a protégé and successor, Romanes chose Lloyd Morgan, who put an end to all this unrestrained speculation. Morgan, a British psychologist, formulated in 1894 the probably most quoted recommendation in all of psychology:

  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 on the psychological scale.15

  Generations of psychologists have dutifully repeated Morgan’s Canon, taking it to mean that it is safe to assume that animals are stimulus-response machines. But Morgan never meant it that way. In fact, he rightly added, “But surely the simplicity of an explanation is no necessary criterion of its truth.”16 Here he was reacting against the mindset according to which animals are blind automata without souls. No self-respecting scientist would talk of “souls,” but to deny animals any intelligence and consciousness came close enough. Taken aback by these views, Morgan added a provision to his canon according to which there is nothing wrong with more complex cognitive interpretations if the species in question has already been proven to have high intelligence.17 With animals such as chimpanzees, elephants, and crows, for which we have ample evidence of complex cognition, we really do not need to start at zero every time we are struck by seemingly smart behavior. We don’t need to explain their behavior the way we would that of, say, a rat. And even for the poor underestimated rat, zero is unlikely to be the best starting point.

  Morgan’s Canon was seen as a variation on Occam’s razor, according to which science should seek explanations with the smallest number of assumptions. This is a noble goal indeed, but what if a minimalist cognitive explanation asks us to believe in miracles? Evolutionarily speaking, it would be a true miracle if we had the fancy cognition that we believe we have while our fellow animals had none of it. The pursuit of cognitive parsimony often conflicts with evolutionary parsimony.18 No biologist is willing to go this far: we believe in gradual modification. We don’t like to propose gaps between related species without at least coming up with an explanation. How did our species become rational and conscious if the rest of the natural world lacks any stepping-stones? Rigorously applied to animals—and to animals alone!—Morgan’s Canon promotes a saltationist view that leaves the human mind dangling in empty evolutionary space. It is to the credit of Morgan himself that he recognized the limitations of his canon and urged us not to confuse simplicity with reality.

  It is less known that ethology, too, arose amid skepticism about subjective methods. Tinbergen and other Dutch ethologists were shaped by the hugely popular illustrated books of two schoolmasters who taught love and respect for nature while insisting that the only way to truly understand animals was to watch them outdoors. This inspired a massive youth movement in Holland, with field excursions every Sunday, that laid the groundwork for a generation of eager naturalists. This approach did not combine well, however, with the Dutch tradition of “animal psychology,” the dominant figure of which was Johan Bierens de Haan. Internationally famous, erudite, and professorial, Bierens de Haan must have looked rather out of place as an occasional guest at Tinbergen’s field site in the Hulshorst, a dune area in the middle of the country. While the younger generation ran around in shorts holding butterfly nets, the older professor came in suit and tie. These visits attest to the cordiality between both scientists before they grew apart, but young Tinbergen soon began to challenge the tenets of animal psychology, such as its reliance on introspection. Increasingly, he put distance between his own thinking and Bierens de Haan’s subjectivism.19 Not being from the same country, Lorenz showed less patience with the old man, whom he—in a play on his name—mischievously dubbed Der Bierhahn (German for “the beertap”).

  Tinbergen is nowadays best known for his Four Whys: four different yet complementary questions that we ask about behavior. But none of them explicitly mentions intelligence or cognition.20 That ethology avoided any mention of internal states was perhaps essential for a budding empirical science. As a consequence, ethology temporarily closed the book on cognition and focused instead on the survival value of behavior. In doing so, it planted the seeds of sociobiology, evolutionary psychology, and behavioral ecology. This focus also offered a convenient way around cognition. As soon as questions about intelligence or emotions came up, ethologists would quickly rephrase them in functional terms. For example, if one bonobo reacted to the screams of another by rushing over for a tight embrace, classical ethologists will first of all wonder about the function of such behavior. They’d have debates about who benefited the most, the performer or the recipient, without asking what bonobos understood about one another’s situations, or why the emotions of one should affect those of another. Might apes be empathic? Do bonobos evaluate one another’s needs? This kind of cognitive query made (and still makes) many ethologists uncomfortable.

  Blaming the Horse

  It is curious that ethologists looked down on animal cognition and emotions as too speculative, while feeling on safe ground with behavioral evolution. If there is one area rife with conjecture, it is how behavior evolved. Ideally, you’d first establish the behavior’s heredity and then measure its impact on survival and reproduction over multiple generations. But we rarely get anywhere close to having this information. With fast-breeding organisms, such as slime molds or fruit flies, these questions may be answerable, but evolutionary accounts of elephant behavior, or human behavior for that matter, remain largely hypothetical since these species don’t permit large-scale breeding experiments. While we do have ways of testing hypotheses and mathematically modeling the consequences of behavior, the evidence is largely indirect. Birth control, technology, and medical care make our own species an almost hopeless test case for evolutionary ideas, which is why we have a plethora of speculations about what happened in the Environment of Evolutionary Adaptedness (EEA). This refers to the living conditions of our hunter-gatherer ancestors, about which we obviously have incomplete knowledge.

  In contrast, cognition research deals with processes in real time. Even though we cannot actually “see” cognition, we are able to design experiments that help us deduce how it works while eliminating alternative accounts. In this regard, it really isn’t different from any other scientific endeavor. Nevertheless, the study of animal cognition is still often considered a soft science, and until recently young scientists were advised away from such a tricky topic. “Wait until you have tenure,” some older professors would say. The skepticism goes all the way back to the curious case of a German horse named Hans, who lived around the time Morgan crafted his canon. Hans became its proof positive. The black stallion was known in German as Kluger Hans, translated as Clever Hans, since he seemed to excel at addition and subtraction. His owner would ask him to multiply four by three, and Hans would happily tap his hoof twelve times. He could also tell you what the date of a given weekday was if he knew the date of an earlier day, and he could tell the square root of sixteen by tapping four times. Hans solved problems he had never heard before. People were flabbergasted, and the stallion became an international sensation.

  Clever Hans was a German horse that drew admiring crowds about a century ago. He seemed to excel at arithmetic, such as addition and multiplication. A more careful examination revealed, however, that his main talent was the reading of human body language. He succeeded only if he could see someone who knew the answer.

  That is, until Oskar Pfungst, a German psychologist, investigated the horse’s abilities. Pfungst had noticed that Hans was successful only if his owner knew the answer and was visible to the horse. If the owner or any other ques
tioner stood behind a curtain while posing their question, the horse failed. It was a frustrating experiment for Hans, who would bite Pfungst if he got too many answers wrong. Apparently, the way he got them right is that the owner would subtly shift his position or straighten his back the moment Hans reached the correct number of taps. The questioner would be tense in face and posture until the horse reached the answer, at which point he would relax. Hans was very good at picking up these cues. The owner also wore a hat with a wide brim, which would be down as long as he looked at Hans’s tapping hoof and go up when Hans reached the right number. Pfungst demonstrated that anyone wearing such a hat could get any number out of the horse by lowering and then raising his head.21

  Some spoke of a hoax, but the owner was unaware that he was cuing his horse, so there was no fraud involved. Even once the owner knew, he found it nearly impossible to suppress his signals. In fact, following the report by Pfungst, the owner was so disappointed that he accused the horse of treachery and wanted him to spend the rest of his life pulling hearses as punishment. Instead of being mad at himself, he blamed his horse! Luckily for Hans, he ended up with a new owner who admired his abilities and tested them further. This was the right spirit, because instead of looking at the whole affair as a downgrading of animal intelligence, it proved incredible sensitivity. Hans’s talent at arithmetic may have been flawed, but his understanding of human body language was outstanding.22

  As an Orlov Trotter stallion, Hans appears to have perfectly fit the description of this Russian breed: “Possessed of amazing intelligence, they learn quickly and remember easily with few repetitions. There is often an uncanny understanding of what is wanted and needed of them at any given time. Bred to love people, they bond very tightly to their owners.”23

  Instead of being a disaster for animal cognition studies, the horse’s exposé proved a blessing in disguise. Awareness of the Clever Hans Effect, as it became known, has greatly improved animal testing. By illustrating the power of blind procedures, Pfungst paved the way for cognitive studies that were able to withstand scrutiny. Ironically, this lesson is often ignored in research on humans. Young children are typically presented with cognitive tasks while sitting on their mothers’ laps. The assumption is that mothers are like furniture, but every mother wants her child to succeed, and nothing guarantees that her body movements, sighs, and nudges don’t cue her child. Thanks to Clever Hans, the study of animal cognition is now more rigorous than that. Dog labs test the cognition of their animals while the human owner is blindfolded or stands in a corner while facing away. In one well-known study, in which Rico, a border collie, recognized more than two hundred words for different toys, the owner would ask for a specific toy located in a different room. This prevented the owner from looking at the toy and unconsciously guiding the dog’s attention. Rico would need to run to the other room to fetch the mentioned item, which is how the Clever Hans Effect was avoided.24

  We owe Pfungst a profound debt for demonstrating that humans and animals develop communication that they are unaware of. The horse reinforced behavior in his owner, and the owner in his horse, whereas everyone was convinced that they were doing something else entirely. While the realization of what was going on moved the historical pendulum to swing firmly from rich to lean interpretations of animal intelligence—where it unfortunately got stuck for too long—other appeals to simplicity have fared less well. Below I describe two examples, one concerning self-awareness and the other culture, both concepts that, whenever mentioned in relation to animals, still send some scholars through the roof.

  Armchair Primatology

  When American psychologist Gordon Gallup, in 1970, first showed that chimpanzees recognize their own reflection, he spoke of self-awareness—a capacity that he said was lacking in species, such as monkeys, that failed his mirror test.25 The test consisted of putting a mark on the body of an anesthetized ape that it could find only, once awake, by inspecting its reflection. Gallup’s choice of words obviously annoyed those leaning toward a robotic view of animals.

  The first counterattack came from B. F. Skinner and colleagues, who promptly trained pigeons to peck at dots on themselves while standing in front of a mirror.26 Reproducing a semblance of the behavior, they felt, would solve the mystery. Never mind that it took them hundreds of grain rewards to get the pigeons to do something that chimpanzees and humans do without any coaching. One can train goldfish to play soccer and bears to dance, but does anyone believe that this tells us much about the skills of human soccer stars or dancers? Worse, we aren’t even sure that this pigeon study is replicable. Another research team spent years trying the exact same training, using the same strain of pigeon, without producing any self-pecking birds. They ended up publishing a report critical of the original study with the word Pinocchio in its title.27

  The second counterattack was a fresh interpretation of the mirror test, suggesting that the observed self-recognition might be a by-product of the anesthesia used in the marking procedure. Perhaps when a chimpanzee recovers from the anesthesia, he randomly touches his face, resulting in accidental contact with the mark.28 This idea was quickly disproved by another team that carefully recorded which facial areas chimpanzees touch. It turned out that the touching is far from random: it specifically targets the marked area and peaks right after the ape has seen his own reflection.29 This was, of course, what the experts had been saying all along, but now it was official.

  B. F. Skinner was more interested in experimental control over animals than spontaneous behavior. Stimulus-response contingencies were all that mattered. His behaviorism dominated animal studies for much of the last century. Loosening its theoretical grip was a prerequisite for the rise of evolutionary cognition.

  Apes really don’t need anesthesia to show how well they understand mirrors. They spontaneously use them to look inside their mouth, and females always turn around to check out their behinds—something males don’t care about. Both are body parts that they normally never get to see. Apes also use mirrors for special needs. For example, Rowena has a little injury on the top of her head caused by a scuffle with a male. Immediately, when we hold up a mirror, she inspects the injury and grooms around it while following the reflection of her movements. Another female, Borie, has an ear infection that we are trying to treat with antibiotics, but she keeps waving her hand in the direction of a table that is empty except for a small plastic mirror. It takes a while before we understand her intentions, but as soon as we hand her the toy, she picks up a straw and angles the mirror such that she can clean out her ear while watching the process in the mirror.

  A good experiment doesn’t create new and unusual behavior but taps into natural tendencies, which is exactly what Gallup’s test did. Given the apes’ spontaneous mirror use, no expert would ever have come up with the anesthesia story. So what makes scientists unaccustomed to primates think they know better? Those of us who work with exceptionally gifted animals are used to unsolicited opinions about how we ought to test them and what their behavior actually means. I find the arrogance behind such advice mind-boggling. Once, in his desire to underscore the uniqueness of human altruism, a prominent child psychologist shouted at a large audience, “No ape will ever jump into a lake to save another!” It was left to me to point out during the Q&A afterward that there are actually a handful of reports of apes doing precisely this—often to their own detriment, since they don’t swim.30

  The same arrogance explains the doubts raised about one of the best-known discoveries in field primatology. In 1952 the father of Japanese primatology, Kinji Imanishi, first proposed that we may justifiably speak of animal culture if individuals learn habits from one another resulting in behavioral diversity between groups.31 By now fairly well accepted, this idea was so radical at the time that it took Western science forty years to catch up. In the meantime, Imanishi’s students patiently documented the spreading of sweet potato washing by Japanese macaques on Koshima Island. The first monkey to do so was a juve
nile female, named Imo, now honored with a statue at the entrance to the island. From Imo the habit spread to her age peers, then to their mothers, and eventually to nearly all monkeys on the island. Sweet potato washing became the best-known example of a learned social tradition, passed on from generation to generation.

  Many years later, this view triggered a so-called killjoy account—an attempt to deflate a cognitive claim by proposing a seemingly simpler alternative—according to which the monkey-see-monkey-do explanation of Imanishi’s students was overblown. Why couldn’t it just have been individual learning—that is, each monkey acquired potato washing on its own without the assistance of anybody else? There might even have been human influence. Perhaps potatoes were handed out selectively by Satsue Mito, Imanishi’s assistant, who knew every monkey by name. She may have rewarded monkeys who dipped their spuds in the water, thus prompting them to do so ever more frequently.32

  The first evidence for animal culture came from sweet-potato-washing Japanese macaques on Koshima Island. Initially, the washing tradition spread among same-aged peers, but nowadays it is propagated transgenerationally, from mother to offspring.

  The only way to find out was to go to Koshima and ask. Having been twice to this island in the subtropical south of Japan, I had a chance to interview the then eighty-four-year-old Mrs. Mito via an interpreter. She reacted with incredulity to my question about food provisioning. One cannot hand out food any way one wants, she insisted. Any monkey that holds food while high-ranking males are empty-handed risks getting into trouble. Macaques are very hierarchical and can be violent, so putting Imo and other juveniles before the rest would have endangered their lives. In fact, the last monkeys to learn potato washing, the adult males, were the first ones to be fed. When I brought up the argument to Mrs. Mito that she might have rewarded washing behavior, she denied that this was even possible. In the early years, potatoes were handed out in the forest far away from the freshwater stream where the monkeys did their cleaning. They’d collect their spuds and quickly run off with them, often bipedally since their hands were full. There was no way for Mito to reward whatever they did in the distant stream.33 But perhaps the strongest argument for social as opposed to individual learning was the way the habit spread. It can hardly be coincidental that one of the first to follow Imo’s example was her mother, Eba. After this, the habit spread to Imo’s peers. The learning of potato washing nicely tracked the network of social relations and kinship ties.34