Grande, a female chimpanzee, piles up four boxes to reach a banana. A century ago Wolfgang K?hler set the stage for animal cognition research by demonstrating that apes can solve problems in their heads by means of a flash of insight, before enacting the solution.
According to K?hler, a sudden insight explained how Sultan put together what he knew about bananas, boxes, and sticks to produce a brand-new action sequence that would take care of his problem. The scientist ruled out imitation and trial-and-error learning, since Sultan had had no previous experience with these solutions nor ever been rewarded for them. The outcome was “unwaveringly purposeful” action in which the ape kept trying to reach his goal despite the numerous stacking errors resulting in the collapse of his towers. A female, Grande, was an even more undeterred and patient architect who once built a wobbly tower of four boxes. K?hler remarked that once a solution was discovered, the apes found it easier to solve similar problems, as if they had learned something about the causal connections. He described his experiments in admirable detail in The Mentality of Apes in 1925, which was at first ignored and then disparaged, but that now stands as a classic in evolutionary cognition.1
The insightful solutions of Sultan and other apes hint at the kind of mental activity that we refer to as “thinking,” even though its precise nature was (and still is) barely understood. A few years later the American primate expert Robert Yerkes described similar solutions.
Frequently I have seen a young chimpanzee, after trying in vain to get its reward by one method, sit down and reexamine the situation as though taking stock of its former efforts and trying to decide what to do next…. More startling by far than the quick passage from one method to another, the definiteness of acts, or the pauses between efforts, is the sudden solution of problems…. Frequently, although not in all individuals or in all problems, correct and adequate solution is achieved without warning and almost instantly.2
Yerkes went on to note that those who only know animals that are good at trial-and-error learning “can scarcely be expected to believe” his descriptions. He thus anticipated the inevitable pushback to these revolutionary ideas. Unsurprisingly, it arrived in the form of trained pigeons shoving little boxes around in a dollhouse so that they could stand on top of them to reach a tiny plastic banana associated with grain rewards.3 How entertaining! At the same time, K?hler’s interpretations were criticized as anthropomorphic. But I heard an amusing antidote to these accusations from an American primatologist brave enough to enter the Skinnerian lion’s den in the 1970s, where he debated tool-using apes.
Without offering specifics, Emil Menzel told me that an eminent East Coast professor once invited him to speak. This professor looked down on primate research and was openly hostile to cognitive interpretations, two orientations that often go together. Perhaps he invited young Menzel to make fun of him, not realizing that the tables might be turned. Menzel treated his audience to spectacular footage of his chimpanzees putting a long pole against their enclosure’s high wall. While some individuals held the pole steady, others scaled it to reach temporary freedom. It was a complex operation since the apes needed to avoid coils of electrified wire while recruiting one another’s assistance at critical moments through hand gestures. Menzel, who had filmed all this himself, decided to run his footage without mentioning intelligence. He was going to be as neutral as possible. His narration was purely descriptive: “You now see Rock grab the pole while glancing at the others,” or “Here a chimpanzee swings over the wall.”4
After his lecture, the professor jumped up to accuse Menzel of being unscientific and anthropomorphic, of attributing plans and intentions to animals that obviously had neither. To a roar of approval, Menzel countered that he had not attributed anything. If this professor had seen plans and intentions, he must have seen them with his own eyes, because Menzel himself had refrained from suggesting any such things.
Interviewing Menzel at my home (he lived nearby) a few years before his death, I took the opportunity to ask him about K?hler. Widely recognized as a great expert on great apes himself, Menzel said it had taken him years working with chimps to fully appreciate this pioneer’s genius. Like K?hler, Menzel believed in watching over and over and thinking through what his observations might mean, even if he’d seen a certain behavior only once. He protested against labeling a single observation an “anecdote,” adding with a mischievous smile, “My definition of an anecdote is someone else’s observation.” If you have seen something yourself and followed the entire dynamic, there usually is no doubt in your mind of what to make of it. But others may be skeptical and need convincing.
Here I cannot resist telling an anecdote of my own. And I do not mean The Great Escape at Burgers’ Zoo, where the chimpanzee colony did exactly what Menzel had documented. After twenty-five apes raided the zoo’s restaurant, we found a tree trunk, far too heavy for a single ape to carry, propped against the inside wall of their enclosure. No, I mean an insightful solution to a social problem—a sort of social tool use—that is my specialty. Two female chimps were sitting in the sun, with their children rolling around in the sand in front of them. When the play turned into a screaming, hair-pulling fight, neither mother knew what to do because if one of them tried to break up the fight, it was guaranteed that the other would protect her offspring, since mothers are never impartial. It is not unusual for a juvenile quarrel to escalate into an adult fight. Both mothers nervously monitored each other as well as the fight. Noticing the alpha female, Mama, asleep nearby, one of them went over to poke her in the ribs. As the old matriarch got up, the mother pointed at the fight by swinging an arm in its direction. Mama needed only one glance to grasp what was going on and took a step forward with a threatening grunt. Her authority was such that this shut up the youngsters. The mother had found a quick and efficient solution to her problem, relying on the mutual understanding typical of chimpanzees.