Are We Smart Enough to Know How Smart Animals Are?(16)

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



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.

Like the scientist who gave us the mirror-anesthesia hypothesis, the one who wrote an entire article debunking the Koshima discovery was a nonprimatologist who, moreover, never bothered to set foot on Koshima or check his ideas with the fieldworkers who had camped for decades on the island. Again, I can’t help but wonder about the mismatch between conviction and expertise. Perhaps this attitude is a leftover of the mistaken belief that if you know enough about rats and pigeons, you know everything there is to know about animal cognition. It prompts me to propose the following know-thy-animal rule: Anyone who wishes to stress an alternative claim about an animal’s cognitive capacities either needs to familiarize him-or herself with the species in question or make a genuine effort to back his or her counterclaim with data. Thus, while I admire Pfungst’s work with Clever Hans and its eye-opening conclusions, I have great trouble with armchair speculations devoid of any attempt to check their validity. Given how seriously the field of evolutionary cognition takes variation between species, it is time to respect the special expertise of those who have devoted a lifetime getting to know one of them.


The Thaw

One morning at Burgers’ Zoo, we showed the chimpanzees a crate full of grapefruits. The colony was in the building where it spends the night, which adjoins a large island, where it spends the day. The apes seemed interested enough watching us carry the crate through a door onto the island. When we returned to the building with an empty crate, however, pandemonium broke out. As soon as they saw that the fruits were gone, twenty-five apes burst out hooting and hollering in a most festive mood, slapping one another’s backs. I have never seen animals so excited about absent food. They must have inferred that grapefruits cannot vanish, hence must have remained on the island onto which the colony would soon be released. This kind of reasoning does not fall into any simple category of trial-and-error learning, especially since it was the first time we followed this procedure. The grapefruit experiment was a one-time event to study responses to cached food.

One of the first tests of inferential reasoning was conducted by American psychologists David and Ann Premack, who presented Sadie, a chimpanzee, with two boxes. They placed an apple in one and a banana in the other. After a few minutes of distraction, Sadie saw one of the experimenters munching on either an apple or a banana. This experimenter then left, and Sadie was released to inspect the boxes. She faced an interesting dilemma, since she had not seen how the experimenter had gotten his fruit. Invariably, Sadie would go to the box with the fruit that the experimenter had not eaten. The Premacks ruled out gradual learning, because Sadie made this choice on the very first trial as well as all subsequent ones. She seemed to have reached two conclusions. First, that the eating experimenter had removed his fruit from one of the two boxes, even if she had not actually seen him do so. And second, that this meant that the other box must still hold the other fruit. The Premacks note that most animals don’t make any such assumptions: they just see an experimenter consume fruit, that’s all. Chimpanzees, in contrast, try to figure out the order of events, looking for logic, filling in the blanks.36