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.26 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.27 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.28
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.29 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.30 This was, of course, what the experts had been saying all along, but now it was official.
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.
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.
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.31
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.32 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 juvenile 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.33
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.34 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.35