Science has a nasty habit of deflating the human ego. Once upon a time, the earth was the centre of the universe and human beings were the centerpiece and purpose of creation, the central focus of the creator of the universe. Then science came along and, before we knew what had hit us, we were demoted to inconsequential specks of dust scrambling around blindly on a pale blue dot orbiting an average star in an inconceivably large universe. Some say that size doesn't matter, but we all know that really it does. Never again would we see ourselves in the same light.
If science in general dealt a blow to our collective ego, evolutionary theory dealt one a hundred times more powerful. As the philosopher Michael Ruse wrote, ‘It is not just that we are on a speck of dust whirling around in the void, but that we ourselves are no more than transformed apes.' Evolutionary theory turns our view of ourselves and our world upside down and inside out. And one of the most important implications of the theory concerns our relationship with the other animals. They and we are no longer products of separate acts of creation. Instead, we are literally distant relatives.
I suppose we're all accustomed by now to the idea that all human beings are related to one another. I look more like my brother than I look like my cousin because I'm more closely related to my brother, and that's exactly the same reason that I look more like my cousin than a random stranger. The species doesn't divide into two groups: relatives and non-relatives. We're all relatives - you, me, Einstein, Buddha, Hitler - it's just that some of us are more distantly related than others. (Try not to think about this next time you're with your spouse, partner, or lover. You're blood relatives!)
All this is true of other animals as well. So, just as we look more like our cousins than our neighbors, we look more like our neighbors than chimpanzees, but it's the same kind of difference in both cases - a difference in relatedness. If you could trace your family tree back to your 250,000th great grandparent, you would come to the most recent common ancestor of all human beings and the chimps and the bonobos. If you went back further, you would eventually come to the most recent common ancestor of yourself and your pet cat or dog, or the bird in the tree outside, or the spider in the shower. All these animals are your long-lost distant cousins. A visit to the zoo is a family reunion.
And it doesn't just stop with animals. When you walk across a lawn or a field, the blades of grass under your feet are literally your distant cousins. So are the bacteria in your gut. Ultimately, all known life on this planet can be traced back to a common ancestor, and every life form that has ever existed here can be placed on a single family tree. All life on earth is literally one large family (albeit a dysfunctional family in which the family members have a habit of eating one another). This is one of the most profound lessons of evolutionary theory.
But Darwin's theory does more than simply stress our kinship with the animals. It challenges the very idea that the inhabitants of this planet can be meaningfully divided into humans and animals in the first place. We now know that we all came about through the same process, and our common origin suggests that we will have more in common with other animals than we previously imagined. We are one animal species among countless millions. Certainly, the human-animal distinction is still workable; after all, we rarely make errors in assigning entities to one category or the other. But after Darwin, the distinction suddenly seems arbitrary - as arbitrary as the equally workable distinction between, say, turtles and non-turtles. Post-Darwin, it is more natural to think of humans as a subset of the category animal. The idea that humans are not animals makes precisely as much sense as the idea that the earth is not a planet, or the sun not a star. We can say these things if we want to. However, if we wish to frame an objective view of the universe (i.e., a view that would be equally valid from the perspective of any species on any planet), we must view the sun as a star, the earth as a planet... and humans as animals.
This suggestion is no doubt far less shocking to modern ears than it was in Darwin's day. Nonetheless, it is not clear that most people have fully taken on board its implications. If they had, then perhaps academic disciplines such as sociology and anthropology would be viewed as specialist branches of zoology; medical doctors would be viewed as a subtype of veterinarians (one that specializes in tending to the health needs of just one species); human rights would be viewed as a subset of animal rights; and the socialization of children would be viewed as one example of the training or domestication of animals (making parents and teachers a subtype of animal trainers). These examples aren't particularly serious. They do make a serious point, though, which is that, at least to some extent, we still view ourselves as set apart from the rest of the animal kingdom. For this reason, we may have a moral blind spot when it comes to our ‘fellow brethren' (as Darwin once described nonhuman animals).
As we all know, a lot of people reacted very negatively to Darwin's theory when he first served it up for public consumption. This was partly because the theory removed the need for God. But that couldn't be the whole story; after all, people could still believe that God created life through the process of evolution (at least if they didn't think too hard about it). The adverse reaction may have been driven in large measure by the fact that a lot of people were insulted by the idea that we are animals. Many felt that Darwin had made monkeys out of them - and in a sense he had. But if you think about it, their outrage at this is a little insulting to monkeys! To some degree, the public outcry following the unveiling of Darwin's theory of evolution revealed a deep-seated prejudice against nonhuman animals. A Ku Klux Klan member would be mortified to learn that he was actually a Black man. Many people's reaction to learning that they are actually animals, or actually apes, is the same. (For some reason, they're not so perturbed about being classed as mammals or as living things. Go figure.)
Another reason people may have been resistant to the idea that humans are animals is that it raises a disturbing possibility: If other animals are no more than complex organic machines, as Descartes and others suggested, then perhaps so too are we. Although a lot of people today are quite at ease with the idea that we are animals, in Darwin's day, it was profoundly unwelcome news. And the fact of the matter is that, for many people, it still is.
Now for some good news: In my next blog posting, I will reveal... the meaning of life!