I want now to talk about a third site, where the question of human uniqueness seems to be an issue between Christian theology and scientific understandings. And that's the question of our relationship with other animals. The question about what differentiates humans from other animals is one with a very long philosophical and theological pedigree. The idea that human beings were the only animals with understanding seems to have been a common place of Greek philosophical thought, at least by the time of Aristotle in the fourth century BC. But there are no shortage of additional features supposed to be unique to human beings. Plato, the ancient Greek philosopher thought religiosity was unique to human beings. Hesiod thought justice was a human distinguishing factor. Aristotle pointed to hair as a unique human feature. He also noted the appreciation of smells beyond that required for food could be unique to human beings. Lactantius, an early Christian theologian thought spirituality and the use of fire was what differentiated humans from other animals. Plato and others thought divinity or the image of divinity was unique, the unique feature of human beings. Aristotle thought that the possession of ears that could not be moved was another feature that distinguished human beings from other animals. Many Greeks and Romans pointed to the capacity to look up to the heavens rather than down to the earth, so this idea of a spiritual capacity again. Moving into the early modern period, Thomas Hobbes thought that human proclivity to do willful hurt to one another was a human distinctive. Karl Marx said the universal production of goods was what distinguished human beings from other animals. Friedrich Nietzsche said that human beings were uniquely able to promise, assess value, exercise conscience and self-control, and display arrogance and vanity. Martin Heidegger said that human beings were uniquely able to form the world. Mark Twain thought human beings were uniquely avaricious, miserly, cruel and uniquely had the ability to blush. Noam Chomsky thought human beings were the unique possessors of language. And Richard Leakey thought human beings were unique in their symbol making. So you get a sense that this question about what makes human beings unique has been both very extended interest for human beings, but also the kinds of answers that have been supplied to that question about what is distinctive about human beings have been so various as to make us think perhaps that they are all suspect in one way or another. And this is a question for modern science as well as traditions of philosophy, because we are developing a better and better sense of the capacities of other animals. And so, scientific knowledge especially in relation to the cognitive capacities of other animals is putting into question many of the things that we've assumed could be relied on to distinguish human beings from other animals. In the link below this video, you'll find a link to a couple of other videos which are absolutely fascinating in unsettling what we think we know about the difference between human beings and other animals. The first you'll see, is a short video showing an experiment that was conducted in relation to a pair of New Caledonian crows. Now in the wild, these crows have been exhibited to use sticks in order to fish out ants, and researchers became interested in the cross because they seemed to be quite sophisticated in their use of tools. So, they could find a stick of exactly the right length in order to obtain the ants that they wanted to feed on. And so in laboratory conditions, the crows were presented with a challenge. There was a long transparent tube at the bottom of which there was a basket with a food reward in, and the basket had a little handle that could be hooked with the right tool. And what the researchers did was put a series of tools for the crows to select, some of which didn't have a hook on so it wouldn't be useful, some of which were the wrong length, and then one tool that was the right length. And what they wanted to experiment with, was to find out how good the crows were about selecting the right tool. But in the video that you'll see, there was a problem. So the male crow perhaps having grown bored from being subjected to too many repeated experiments, took the only suitable tool away and flew off to the other side of the enclosure. And so the female crow was left with a challenge of how to get the food out with no appropriate tool. But what you can see in the video is she reacts in an astonishing way. After quickly assessing that none of the tools are appropriate, she picks up a long piece of wire without a hook on the end, grabs it with her foot, and with a combination of a foot and her beak she bends it into a hook, and then uses this refashioned tool in order to successfully obtain the food reward. Now this is a remarkable video because for a long time, people thought that tool making was another of the things that could be reliably used to distinguish between human beings and other animals. But first of all, tool use but then tool making, when it became apparent, lots of other animals use tools in different ways. And now, there's lots of research on all kinds of different species of animals using and making tools. But we could see that even in species where we might not expect to find it, such as bird species, we can see the innovative use of tools to solve problems in order to achieve what the species want to do in the world. So, human beings even in relation to crows are not unique in our use or even our fashioning of tools. Now, I'd like to move on to a second example that is very, very surprising in relation to our understanding of the capacities of other animals. Again, below this video, you'll find two examples of first of all, human beings and then chimpanzees trying to play a video game. Perhaps you've tried brain training apps on your phone or iPad. In this kind of brain training game, what was done was on the computer screen, a number of digits was flashed up briefly on the screen and then the digits were taken away, and instead where the digits were, there were empty boxes. And the game was to click on the empty boxes in numerical order. So this is a test first of symbolic recognition. So, the individual engaged in the game needed to know the order of these numeric symbols. And then, it's a test of memory. How quickly can you remember a set of numeric symbols and then be able to click on them in order. What you see in the first video is a human being playing that game, and you might sympathize as you watch the video. You can see the numbers displayed very briefly on the screen and then disappear into empty boxes. And sometimes when the human being is concentrating hard, they can get it right and click on the symbols in the right order, and sometimes they can't. The numbers only appear for a very short period and then they go away, and sometimes the human being fails to click on them in order. But in the second video, you can see a chimpanzee playing that game. Now, not all the chimpanzees were very good at the game, but some individual chimpanzees were astonishingly good. And what the researchers found was absolutely remarkable in my view, that some of the chimpanzees were much better than any of the human volunteers. Again, let's take stock of what's going on here. The chimpanzees are learning a human symbolic system. They're learning that there's an order to the digits, and then they're able to be trained in order to press on those digits after the numbers have been displayed for a very short period of time. So it turns out chimpanzees are better in their short term memory for human numbers than humans are. So many of the ways in which the Greeks and later philosophical schools thought that human beings were unique seemed to be challenged at a very fundamental level by this kind of evidence of non-human animal capacity. And so these kinds of experiments and these kinds of scientific discoveries seem to ask really profound questions about what exactly we think is the difference between human beings and other animals. So we've got tool use and tool refashioning in New Caledonian crows in that first video. And in that second pair, we've got evidence that chimpanzees are really good at recognizing numbers and remembering them. But you might be thinking, well, okay, so crows are quite good at bending wire and solving problems that way, and chimpanzees turn out to be quite good at remembering numbers, but there are other things that definitely only human beings can do. You might think, well, we've got no good evidence that any non-human animal has ever written a novel, for example, or we've got no good evidence that non-human animals can perform abstract calculus. And that's probably true, although, perhaps we'll find out in some future of some novel writing dolphin or gorilla, but it's probably true that those things are unique to human beings. But what's interesting, is that there are not properties that are true of all human beings. So, if we're looking for the kind of distinction that that grand philosophical distinction was looking for, some kind of one marker factor that could be used to reliably distinguish between human beings and every kind of animal. Examples like abstract calculus or novel writing are not going to do the job because some human beings and only human beings will be on one side of the line, but the vast majority of human beings alongside all of non-human animals are going to be on the other. And it turns out that it's very hard to work out any particular characteristic that would reliably distinguish between humans and other animals. So we might need to think in a much more complex way about how human beings and other animals relate. We might have to give up an idea that there is one particular marker that we could use to reliably distinguish between human beings and other animals.
