The wrong sort of question

By the year 1799, the Great Chain of Being had effectively been sundered, although some still clutched the shattered links in the hope that some linear order to the Creation would be found. The concept was no longer tenable, Charles White having to base his entire case for the superiority of Europeans over people of Asian and African descent (each "race" acting as a species to fill in a slot in the chain of "lower" to "higher") in An Account of the Regular Gradation in Man, and in Different Animals and Vegetables on subjective aesthetic preferences. In the years leading up to Darwin the idea that life evolved began to pick up more steam, the Chain disappearing as a valid concept, yet vestiges still remain with us. Indeed, no question belies our attachment to the chain more than "What makes us human?"

If we compare ourselves with a chimpanzee or bonobo, our closest living relatives, there are a number of differences that can be recorded and compared. We stand upright while they are knuckle-walkers; we have 23 pairs of chromosomes, chimpanzees have 24; we have a flat face and they have a prognathus face; etc. None of these basic observations really get to the heart of the question being asked, however. Even though it is clear that we cannot label ourselves as subjectively better than any other species, many of us still operate under this assumption. We are not asking "What makes us apes?" or "How primate-like are we?", but rather "What separates us from the rest of nature?" or "What makes us distinct from sub-humans?"

Many of the barriers erected to make our species distinct from all others have centered around aspects of intelligence. Traditionally we've seen ourselves as tool-makers and masters of language, intellectual heavyweights that no animal could ever hope to approach (at least beyond what was archaically termed the "idiot" or "imbecile" grades). Perhaps this is why debates over whether apes can understand and use human language have been so vociferous; language is seen as something distinctly human, and any suggestion that another species might have it is not going to be readily accepted. (See Adrian Desmond's The Ape's Reflexion and the more recent book The Simian Tongue by Gregory Radick).

Our concern over the habits and abilities of apes is primarily moving in one direction; how "human-like" are they? What the apes might tell us about ourselves is often downplayed or pushed aside (explicitly so in Frans de Waal's Chimpanzee Politics), partly because it would be irresponsible to give the impression that we are no different from apes, but also because such analysis hits a little close to home. Anyone who has worked in an office will likely be able to recognize all the "social grooming" that goes on when tuned into it, yet we often come up with numerous seemingly-reasonable justifications to downplay any similarities between what we're doing and what an individual in a troop of baboons might be doing (See the recently published book Baboon Metaphysics for more about the social habits of baboons). (Baboons are not apes, though, and the habits of monkeys are usually even more suspect when it comes to implications for our own species.)

Much like the concept of biological races, the biological concept of what makes us "human" has essentially fallen by the wayside. Recent books about our fossil relatives bear titles like Extinct Humans and The Last Human, and drawing the line in the sand where "humanity" starts seems to be becoming a more arbitrary task. Phylogeny might ultiamtely cast the deciding vote, our side of the split with the line that led to chimpanzees being labeled the "human side," but this may cause some discomfort among those who don't wish to call Sahelanthropus, Orrorin, Australopithecus, or even Homo erectus human.

None of what I've said here is new or particularly earth-shattering, and yet is doesn't seem to have fully sunk in. We continue to use ourselves to measure the capacity and ability of our nearest relatives, judging most harshly those that are the closest to us. Attention to detail and probing questions are warranted, of course, as they may help elucidate questions that remain about our own species, but such inquiries are often paired with a seemingly desire to keep apes at arm's length. In time this may change, but for now it seems that we would rather not look at the monkey in the mirror.