What I Learned From Tickling Apes

TICKLING a juvenile chimpanzee is a lot like tickling a child. The ape has the same sensitive spots: under the armpits, on the side, in the belly. He opens his mouth wide, lips relaxed, panting audibly in the same “huh-huh-huh” rhythm of inhalation and exhalation as human laughter. The similarity makes it hard not to giggle yourself.

The ape also shows the same ambivalence as a child. He pushes your tickling fingers away and tries to escape, but as soon as you stop he comes back for more, putting his belly right in front of you. At this point, you need only to point to a tickling spot, not even touching it, and he will throw another fit of laughter.

Laughter? Now wait a minute! A real scientist should avoid any and all anthropomorphism, which is why hard-nosed colleagues often ask us to change our terminology. Why not call the ape’s reaction something neutral, like, say, vocalized panting? That way we avoid confusion between the human and the animal.

The term anthropomorphism, which means “human form,” comes from the Greek philosopher Xenophanes, who protested in the fifth century B.C. against Homer’s poetry because it described the gods as though they looked human. Xenophanes mocked this assumption, reportedly saying that if horses had hands they would “draw their gods like horses.” Nowadays the term has a broader meaning. It is typically used to censure the attribution of humanlike traits and experiences to other species. Animals don’t have “sex,” but engage in breeding behavior. They don’t have “friends,” but favorite affiliation partners.

Given how partial our species is to intellectual distinctions, we apply such linguistic castrations even more vigorously in the cognitive domain. By explaining the smartness of animals either as a product of instinct or simple learning, we have kept human cognition on its pedestal under the guise of being scientific. Everything boiled down to genes and reinforcement. To think otherwise opened you up to ridicule, which is what happened to Wolfgang Köhler, the German psychologist who, a century ago, was the first to demonstrate flashes of insight in chimpanzees.

Köhler would put a banana outside the enclosure of his star performer, Sultan, while giving him sticks that were too short to reach the fruit through the bars. Or he would hang a banana high up and spread boxes around, none of which were tall enough to reach the fruit. At first, Sultan would jump or throw things at the banana or drag a human by the hand toward it, hoping to use him as a footstool. If this failed, he would sit around without doing anything, pondering the situation, until he might hit on a solution. He’d jump up suddenly to put one bamboo stick inside another, making a longer stick. He’d also stack boxes to build a tower tall enough to attain his reward. Köhler described this moment as the “aha! experience,” not unlike Archimedes running through the streets shouting “Eureka!”

According to Köhler, Sultan showed insight by combining what he knew about boxes and sticks to produce a brand-new action sequence to take care of his problem. It all took place in his head, without prior rewards for his eventual solution. That animals may show mental processes closer to thinking than learning was so unsettling, though, that still today Köhler’s name is hissed rather than spoken in some circles. Naturally, one of his critics argued that the attribution of reasoning to animals was an “overswing of the theoretical pendulum” back “toward anthropomorphism.”

We still hear this argument, not so much for tendencies that we consider animalistic (everyone is free to speak of aggression, violence and territoriality in animals) but rather for traits that we like in ourselves. Accusations of anthropomorphism are about as big a spoiler in cognitive science as suggestions of doping are of athletic success.

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