What, if anything, makes humans different from other animals? For centuries, if not millennia, humans have never doubted their own superiority, and insisted that the differences are differences of kind, not just of degree.
Although some human cultures see people as part of nature, the Judeo-Christian view – that God created humans in his own image and gave them dominion over the Earth – came to dominate. We now know that humans evolved from the same ancestors that gave rise to other living primates, from lemurs to chimpanzees. There is no one point in evolutionary history that we can identify as the moment when humans became different in kind to other animals.
Yet we continue to cling on to this sense of our own exceptionalism. A number of features have been claimed as uniquely human, from consciousness, mind and free will, to language, technology and culture. But science is increasingly showing that none of these assertions are tenable.
Consciousness is our awareness not just of our surroundings, but of ourselves. It is by definition subjective – an internal state known only to its possessor. But scientists have found objective correlations of consciousness, in the form of observed behaviour and brain activity, not just in humans, but also in mammals, birds and even octopuses.
Aspects of consciousness, such as intentional behaviour, making choices and self-recognition, have been widely observed in non-human animals. One simple test uses a mirror to see whether the animal in question knows it is looking at itself, rather than another individual. A number of different primates have passed the test, as well as Asian elephants, bottle-nosed dolphins, orcas and the Eurasian magpie.
Tool use turns out not to be uniquely human either. Chimpanzees poke twigs to ‘fish’ for ants, sea otters use stones to dislodge and break open shellfish, and a species of crow living in New Caledonia whittles branches into hooks in order to extract food from inaccessible crannies.
‘Man is an invention of recent date.’
Michel Foucault, The Order of Things (1966)
Whether such behaviours are instinctive or learned cannot always be judged. If they are learned, then we can talk about that species acquiring a culture (see here ). A well-known instance of animal culture involved a group of Japanese macaques. One individual started washing sweet potatoes in the sea before eating them, rather than brushing the sand off, as her companions did. Others began to copy her, and this behaviour was passed down the generations.
The vocalizations of various species of whale and dolphin change from group to group, so each ‘song’ seems to reinforce the identity of that group. The songs also change over time. We don’t know if these songs hold sufficient information to count as language – no one has yet established if they have ‘meaning’. The same uncertainty applies to other animal vocalizations. Although chimpanzees have been taught to use sign-language, sceptics have pointed out that the failure of any signing chimp to ask a question suggests that this trait is unique to humans. However, over thirty years animal psychologist Irene Pepperberg taught Alex, an African grey parrot, some basic English, and also to distinguish various colours, shapes and sizes. Alex eventually asked what colour he was. Having been told the answer six times, he learned that he was ‘grey’. This is the only known example of a non-human asking an existential question. Nevertheless, the line between human and non-human is blurred.