Are We Smart Enough to Know How Smart Animals Are?(38)

This is not to deny that humans are special—in some ways we evidently are—but if this becomes the a priori assumption for every cognitive capacity under the sun, we are leaving the realm of science and entering that of belief. Being a biologist who teaches in a psychology department, I am used to the different ways disciplines approach this issue. In biology, neuroscience, and the medical sciences, continuity is the default assumption. It couldn’t be otherwise, because why would anyone study fear in the rat amygdala in order to treat human phobias if not for the premise that all mammalian brains are similar? Continuity across life-forms is taken for granted in these disciplines, and however important humans may be, they are a mere speck of dust in the larger picture of nature.

Increasingly, psychology is moving in the same direction, but in other social sciences and the humanities discontinuity remains the typical assumption. I am reminded of this every time I address these audiences. After a lecture that inevitably (even if I don’t always mention humans) reveals similarities between us and the other Hominoids, the question invariably arises: “But what then does it mean to be human?” The but opening is telling as it sweeps all the similarities aside in order to get to the all-important question of what sets us apart. I usually answer with the iceberg metaphor, according to which there is a vast mass of cognitive, emotional, and behavioral similarities between us and our primate kin. But there is also a tip containing a few dozen differences. The natural sciences try to come to grips with the whole iceberg, whereas the rest of academia is happy to stare at the tip.

In the West, fascination with this tip is old and unending. Our unique traits are invariably judged to be positive, noble even, although it wouldn’t be hard to come up with a few unflattering ones as well. We are always looking for the one big difference, whether it is opposable thumbs, cooperation, humor, pure altruism, sexual orgasm, language, or the anatomy of the larynx. It started perhaps with the debate between Plato and Diogenes about the most succinct definition of the human species. Plato proposed that humans were the only creatures at once naked and walking on two legs. This definition proved flawed, however, when Diogenes brought a plucked fowl to the lecture room, setting it loose with the words “Here is Plato’s man.” From then on the definition added “having broad nails.”

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!”