I am willing to believe a recent study that found cat lovers to be more intelligent than dog lovers, but this comparison is a piece of cake relative to one drawing a contrast between actual cats and dogs. Both species are so different that it would be hard to design an intelligence test that both of them perceive and approach similarly. At issue, however, is not just how two animal species compare but—the big gorilla in the room—how they compare to us. And in this regard, we often abandon all scrutiny. Just as science is critical of any new finding in animal cognition, it is often equally uncritical with regard to claims about our own intelligence. It swallows them hook, line, and sinker, especially if they—unlike Ayumu’s feat—are in the expected direction. In the meantime, the general public gets confused, because inevitably any such claims provoke studies that challenge them. Variation in outcome is often a matter of methodology, which may sound boring but goes to the heart of the question of whether we are smart enough to know how smart animals are.
Methodology is all we have as scientists, so we pay close attention to it. When our capuchin monkeys underperformed on a face-recognition task on a touchscreen, we kept staring at the data until we discovered that it was always on a particular day of the week that the monkeys fared so poorly. It turned out that one of our student volunteers, who carefully followed the script during testing, had a distracting presence. This student was fidgety and nervous, always changing her body postures or adjusting her hair, which apparently made the monkeys nervous, too. Performance improved dramatically once we removed this young woman from the project. Or take the recent finding that male but not female experimenters induce so much stress in mice that it affects their responses. Placing a T-shirt worn by a man in the room has the same effect, suggesting that olfaction is key.12 This means, of course, that mouse studies conducted by men may have different outcomes than those conducted by women. Methodological details matter much more than we tend to admit, which is particularly relevant when we compare species.
Knowing What Others Know
Imagine that aliens from a distant galaxy landed on earth wondering if there was one species unlike the rest. I am not convinced they would settle on us, but let’s assume they did. Do you think they’d do so based on the fact that we know what others know? Of all the skills that we possess and all the technology that we have invented, would they zoom in on the way we perceive one another? What an odd and capricious choice this would be! But it is precisely the trait that the scientific community has considered most worthy of attention for the last two decades. Known as theory of mind, abbreviated ToM, it is the capacity to grasp the mental states of others. And the profound irony is that our fascination with ToM did not even start with our species. Emil Menzel was the first to ponder what one individual knows about what others know, but he did so for juvenile chimpanzees.
In the late 1960s Menzel would take a young ape by the hand out into a large, grassy enclosure in Louisiana to show her hidden food or a scary object, such as a toy snake. After this, he would bring her back to the waiting group and release them all together. Would the others pick up on the knowledge of one among them, and if so, how would they react? Could they tell the difference between the other having seen food or a snake? They most certainly could, being eager to follow a chimp who knew a food location or being reluctant to stay with one who’d just seen a hidden snake. Copying the other’s enthusiasm or alarm, they had an inkling of his knowledge.13
Scenes around food were especially telling. If the “knower” ranked below the “guessers,” the former had every reason to conceal his or her information to keep the food out of the wrong hands. We recently repeated these experiments with our own chimps and found the same subterfuge as reported by Menzel. Katie Hall would remove two of our chimps from their outdoor enclosure and keep them temporarily in a building. Low-ranking Reinette would have a small window from which to look out into the enclosure, whereas high-ranking Georgia would have no such view. Katie would walk around hiding two food items: one entire banana and one entire cucumber. Guess which one chimps prefer! She’d stuff food underneath a rubber tire, in a hole in the ground, in the deep grass, behind a climbing pole, or some other place, while Reinette followed her every move from inside. Then we’d release both chimps at the same time. By then, Georgia had learned that we’d hide food, but she’d have no clue about the location. She had learned to carefully watch Reinette, who would walk around as nonchalantly as possible while gradually bringing Georgia closer and closer to the concealed cucumber. With Reinette sitting nearby, Georgia would eagerly dig up the veggie. While she was busy, Reinette would hurry toward the banana.
The more experiments we conducted, though, the more Georgia caught on to these deceptive tactics. It is an unwritten rule among chimps that once something is in your hands or mouth, it is yours, even if you are of low status. Before this moment, however, when two individuals approach food, the dominant will enjoy priority. For Georgia, therefore, the trick was to arrive at the banana before Reinette could put her hands on it. After many tests with different combinations of individuals, Katie concluded that high-status chimps exploit the other’s knowledge by carefully monitoring their gaze direction, looking where they are looking. Their partners, on the other hand, do their utmost to conceal their knowledge by not looking where they don’t want the other to go. Both chimps seem exquisitely aware that one possesses knowledge that the other lacks.14
This cat-and-mouse setup shows how much bodies matter. Much of our knowledge about ourselves comes from inside our bodies, and much of what we know about others comes from reading their body language. We are very attuned to the postures, gestures, and facial expressions of others, as are many other animals, such as our pets. This is why Menzel never liked the “theory” language that took over once ToM exploded as a topic as a result of other ape research. The central question became whether apes or children hold a theory about the minds of others.15 I have trouble with this terminology, too, because it makes it sound as if we understand others through a rational evaluation not unlike the way we figure out physical processes, such as how water freezes or how continents drift apart. It sounds far too cerebral and disembodied. I seriously doubt that we, or any other animal, grasp the mental states of someone else at such an abstract level.
Some even speak of mindreading, a term reminiscent of the telepathic trickery of magicians (“Let me guess what card you have in mind”). The magician, however, operates entirely on the basis of which card he has seen you lay your eyes on, or some other visual cue, because there is no such thing as mindreading. All we can do is figure out what others have seen, heard, or smelled, and deduce from their behavior what their next step may be. Putting all this information together is no minor feat and takes extensive experience, but it is body reading, not mindreading. It allows us to look at a situation from the viewpoint of another, which is why I prefer the term perspective taking. We use this capacity to our own advantage but also to the advantage of others, such as when we respond to someone else’s distress or fulfill the needs of another person. This obviously gets us closer to empathy than ToM.