Psychologist Daniel Gilbert once wrote on the unwritten vow taken by psychologists:
Few people realise that psychologists also take a vow, promising that at some point in their professional lives they will publish a book, a chapter or at least an article that contains the sentence: ‘The human being is the only animal that…’ We are allowed to finish the sentence any way we like, but it has to start with those eight words.
Most of us wait to relatively late in our careers to fulfil this solemn obligation because we know that successive generations of psychologists will ignore all the other words that we managed to pack into a lifetime of well-intentioned scholarship and remember us mainly for how we finished The Sentence.
We also know that the worse we do, the better we will be remembered. For instance, those psychologists who finished The Sentence with ‘can use language’ were particularly well remembered when chimpanzees were taught to communicate with hand signs.
And when researchers discovered that chimps in the wild used sticks to extract tasty termites from their mounds (and to bash each other over the head now and again), the world suddenly remembered the full name and mailing address of every psychologist who ever finished The Sentence with the words ‘uses tools’.
So it is with good reason that most psychologists put off completing The Sentence for as long as they can, hoping that if they wait long enough, they might just die in time to avoid being publicly humiliated by a monkey.
From p3 of Stumbling on Happiness (ISBN 9780007183135).
Every time I write (or someone else writes) that humans are animals, scores of people will rise up in ire, attempting to complete the sentence. We are special, and special in our specialness. As I argued in the last post, of course humans are special: they are members of a species, and species are special. With that out of the way, in what way are humans special? What is it we do that is special, that other animals do not do? The answer is that we do a lot of things other animals do not do, and they also do a lot of things we do not do. Bats navigate by sonar (but so do some blind humans), ants follow pheromone trails (but we are affected by pheromones too) and so on.
Humans do one thing that other animals don’t: they reproduce with humans only. Now this hasn’t always been true. Our ancestors did hybridise with related species (something that many primates do, by the way). But now there are no extant hominids with whom we can successfully mate. So that’s fairly trivial.
Another thing that humans do is manipulate objects with a fairly fine precision. Other primates have fewer short twitch muscle fibres, and so lack the degree of fine control we have when making and using tools. This is a matter of degree, not kind, though. Our opposable thumb gives us the ability to hold things tightly but carefully, but other primates, especially chimps, can hold things and use them as tools.
We use language, but other animals do too (especially primates), but one thing we do they don’t is use complex grammars, with recursive syntax. Gorillas and chimps use language in the same fashion as a three year old: verbs, objects and subjects, with the occasional adjective thrown in. Humans construct very complex sentences (try learning philosophical German!). Again, a difference of degree. However, while we use symbolic communication (as Deacon calls us, we are the Symbolic Species), some primates also use a form of symbolic communication, especially in the use of displacement (referring to objects that are not present).
We have culture. So do whales, monkeys, birds, and even fish. But human culture is specifically symbolic. Many think this is a unique fact of humans and what marks us out from other animals. It may be, but all the elements of human culture are themselves merely honed or elaborated versions of ancestral and shared traits or analogous traits with other species. We are more complex in our culture, but a bee is more complex in its use of visual information, etc.
We have morality. So do many other species. De Waal even thinks, I believe correctly, that all mammalian species that are social have some form of norm following. Certainly the primates do. Chimps and other apes have been tested and show that they punish defectors and reward cooperators in social games.
We have technology. Of course our technology is much more complex than other animals, and can be considered our special adaptation. We developed stone tool technology early in our evolution (possibly in our predecessor species H erectus), and if anyone thinks that stone technology is simple, they’ve never tried to make some. I think the gap between stone technology and what came before is greater than the gap between it and our present technology, cognitively speaking. But other animals do have technology. Chimps have been known to carry stones some distance for the purpose of cracking nuts. If that isn’t technology, I cannot say what is.
Okay, so we are special in some ways, but those ways are not unique to us. This seemingly contradictory statement can be resolved by realising that we have special forms of shared traits and behaviours. Why does it cause so many people grief to say this?
The western tradition of the human/nature divide is deep, and probably goes back to Mesopotamian times. Humans are somehow isolated from nature, or in control of it. We know that organisms construct part of their environment as a general rule (even bacteria and plants), so this is not novel. But it became somehow the default view that humans are, as the old saying had it, a little lower than angels but higher than animals. Here, “animal” means all animals apart from humans, of course. When Linnaeus classified humans as animals (in the kingdom Animalia), this began to be challenged. The Enlightenment view that humans are self-standing agents capable of knowledge and moral action was degraded almost from the time it was established.
Many other societies have or do see humans as part of the general natural world. It is not inevitable that we must distinguish ourselves as the head of creation or a separate kind from all other animals. But in the west, partly as a result of Aristotle and partly as a result of Christian and Islamic theology, we think the world is arranged into simple to complex beings. This, the Great Chain of Being, is a remarkably persistent viewpoint. It is contrary to all we know of the biological world, and remains a largely theologically motivated view. In fact, it broke down well before Darwin.
But still philosophers, theologians and the ordinary public seem to think that humans have attained some level of complexity or sophistication that marks them out, not in degree, but in kind. We are the only animal that… And it’s neither true by definition, nor consonant with the facts.
To say this is not, despite the critics, to demean human beings. We remain as valuable to us, as we ever were. But we are part of nature, not apart from it. We modify and try (in vain often) to control our environment, but without it we are simply dead. It is not there for us, nor we for it. The evolutionary view of humans enriches our understanding, but it does not mean we have to ignore our own special traits. There is a long tradition of naturalising humans, but we remain humans. Why is that so hard?