In 1784 Johann Wolfgang von Goethe triumphantly announced that he had discovered the biological roots of humanity: a tiny piece of bone in the human upper jaw known as the os intermaxillare. Though present in other mammals, including apes, the bone had never before been detected in our species and had therefore been labeled “primitive” by anatomists. Its absence in humans had been taken as something we should be proud of. Apart from being a poet, Goethe was a natural scientist, which is why he was delighted to link our species to the rest of nature by showing that we shared this ancient bone. That he did so a century before Darwin reveals how long the idea of evolution had been around.
The same tension between continuity and exceptionalism persists today, with claim after claim about how we differ, followed by the subsequent erosion of these claims.9 Like the os intermaxillare, uniqueness claims typically cycle through four stages: they are repeated over and over, they are challenged by new findings, they hobble toward retirement, and then they are dumped into an ignominious grave. I am always struck by their arbitrary nature. Coming out of nowhere, uniqueness claims draw lots of attention while everyone seems to forget that there was no issue before. For example, in the English language (and quite a few others), behavioral copying is denoted by a verb that refers to our closest relatives, hinting at a time when imitation was no big deal and was considered something we shared with the apes. But when imitation was redefined as cognitively complex, dubbed “true imitation,” all of a sudden we became the only ones capable of it. It made for the peculiar consensus that we are the only aping apes. Another example is theory of mind, a concept that in fact derives from primate research. At some point, however, it was redefined in such a manner that it seemed, at least for a while, absent in apes. All these definitions and redefinitions take me back to a character played by Jon Lovitz on Saturday Night Live, who conjured unlikely justifications of his own behavior. He kept digging and searching until he believed his own fabricated reasons, exclaiming with a self-satisfied smirk, “Yeah! That’s the ticket!”
With regard to technical skills, the same thing happened despite the fact that ancient gravures and paintings commonly depicted apes with a walking cane or some other instrument, most memorably in Carl Linnaeus’s Systema Natura in 1735. Ape tool use was well known and not the least bit controversial at the time. The artists probably put tools in the apes’ hands to make them look more humanlike, hence for exactly the opposite reason anthropologists in the twentieth century elevated tools to a sign of brainpower. From then on, the technology of apes was subjected to scrutiny and doubt, ridicule even, while ours was held up as proof of mental preeminence. It is against this backdrop that the discovery (or rediscovery) of ape tool use in the wild was so shocking. In their attempts to downplay its importance, I have heard anthropologists suggest that perhaps chimpanzees learned how to use tools from humans, as if this would be any more likely than having them develop tools on their own. This proposal obviously goes back to a time when imitation had not yet been declared uniquely human. It is hard to keep all those claims consistent. When Leakey suggested that we must either call chimpanzees human, redefine what it is to be human, or redefine tools, scientists predictably embraced the second option. Redefining man will never go out of fashion, and every new characterization will be greeted with “Yeah! That’s the ticket!”
Even more egregious than human chest beating—another primate pattern—is the tendency to disparage other species. Well, not just other species, because there is a long history of the Caucasian male declaring himself genetically superior to everyone else. Ethnic triumphalism is extended outside our species when we make fun of Neanderthals as brutes devoid of sophistication. We now know, however, that Neanderthal brains were slightly larger than ours, that some of their genes were absorbed into our own genome, and that they knew fire, burials, hand-axes, musical instruments, and so on. Perhaps our brothers will finally get some respect. When it comes to the apes, however, contempt persists. When in 2013 the BBC website asked Are You as Stupid as a Chimpanzee? I was curious to learn how they had pinpointed the level of chimpanzee intelligence. But the website (since removed) merely offered a test of human knowledge about world affairs, which had nothing to do with apes. The apes merely served to draw a contrast with our species. But why focus on apes in this regard rather than, say, grasshoppers or goldfish? The reason is, of course, that everyone is ready to believe that we are smarter than these animals, yet we are not entirely sure about species closer to us. It is out of insecurity that we love the contrast with other Hominoids, as is also reflected in angry book titles such as Not a Chimp or Just Another Ape?10
The same insecurity marked the reaction to Ayumu. People watching his videotaped performance on the Internet either did not believe it, saying it must be a hoax, or had comments such as “I can’t believe I am dumber than a chimp!” The whole experiment was taken as so offensive that American scientists felt they had to go into special training to beat the chimp. When Tetsuro Matsuzawa, the Japanese scientist who led the Ayumu project, first heard of this reaction, he put his head in his hands. In her charming behind-the-scenes look at the field of evolutionary cognition, Virginia Morrell recounts Matsuzawa’s reaction:
Really, I cannot believe this. With Ayumu, as you saw, we discovered that chimpanzees are better than humans at one type of memory test. It is something a chimpanzee can do immediately, and it is one thing—one thing—that they are better at than humans. I know this has upset people. And now there are researchers who have practiced to become as good as a chimpanzee. I really don’t understand this need for us to always be superior in all domains.11
Even though the iceberg’s tip has been melting for decades, attitudes barely seem to budge. Instead of discussing them any further here or going over the latest uniqueness claims, I will explore a few claims that are now close to retirement. They illustrate the methodology behind intelligence testing, which is crucial to what we find. How do you give a chimp—or an elephant or an octopus or a horse—an IQ test? It may sound like the setup to a joke, but it is actually one of the thorniest questions facing science. Human IQ may be controversial, especially while we are comparing cultural or ethnic groups, but when it comes to distinct species, the problems are a magnitude greater.