When I was young, family dinners would result in a wide range of conversations - everything from the difference between girls and boys to what it was like to live through the Second World War. I don't recall all the conversations but I do remember one line of questions - what separates humans from animals? It was a question we returned to many times over the years.
The glib answer is: "we have opposable thumbs." Our ability to grasp objects is governed to a large extent by our hands (and feet). I can pick up a hammer, a sword, or a pen because these objects have been shaped by human ingenuity to fit into our hands and take advantage of lateral movement of our thumbs relative to our fingers. A dog, lacking a thumb, is not able to manipulate any of these devices.
Of course, we are not the only creatures with opposable thumbs. Many creatures have hands with similar shapes. All of the primates, for example, can grasp in pretty much the same way. Certainly our close cousins, the chimpanzees and bonobos are able to utilize hammers, swords, and pens although not with our devastating effectiveness.
There are other creatures with grasping capacity. Raccoons come to mind. They inhabit the neighbourhood where I grew up and were capable of opening gates and garbage cans. Their hands are fairly dexterous.
If not our opposable thumbs, then, what distinguishes humans from animals?
The next round of conversation was about our use of tools. Humans modify the world around us to create hammers, swords, and pens.
When I was young, there wasn't a lot known about tool use by animals. Most instances where tool use was observed were either dismissed as accidental or simply chalked up to instinctual behaviour. A lot has changed in the past 50 years.
We now know a whole range of animals take advantage of natural objects to modify their environment and provide access to food. Otters, for example, will dive for both food and rocks with which to crack open shells. They will float on their backs and crack open tough shells with repeated blows. Elephants use rocks and logs to modify drinking holes. Even pigs use improvised shovels to help dig nests.
But some creatures go well beyond simply using available materials and actually modify their tools. Birds have been observed stripping a thin stick bare so as to be able to poke it into a hole in search of insects. Crows have been observed to modify sticks even further, bending them to fit around corners and building hooks to snag food items. Watching a crow solve a puzzle or problem is quite enlightening.
Our closer relatives, the apes and monkeys, go to great lengths in their use of tools and their understanding of their environment. Orangutans are considered the best "escape artists" at the zoo. They have been known to hide bits of metal from their keepers which they then use to pick the locks on their cages. Wild chimpanzees have been observed making sponges by chewing and matting together leaves.
Man-the-tool-maker is no longer one of the goalposts defining our species.
If it is not physiology or tool-making, maybe it is language which separates us from animals. Except over the past 50 years, we have learned a great deal about animal communication. Animals have languages, albeit of a simpler form than ours, but they are still able to communicate fairly sophisticated concepts. More to the point, they are able to recognize others by their voices.
One experiment conducted on meerkats involve recording the voice of one member of a tribe and then playing it back for other members. The animals became clearly agitated and confused when the voice was played from different locations in rapid succession. The animals could not understand how their comrade could be in two locations at once.
It is not language which separates us from animals. Indeed, a BBC video will even teach you how to speak meerkat if you are so inclined.
No. It is not having language which makes us unique but it may be what we do with our language which separates Homo sapiens. In his book, Sapiens, Yuval Harari makes the case for our ability to tell stories as the defining characteristic of our species.
About 70,000 years ago, long after we had tamed fire and developed the ability to shape tools, our species engaged in a cognitive leap forward. We likely developed the capacity to tell stories which allowed for one generation to pass on knowledge to the next. But they also allowed us to imagine and it is imagination which has allowed us to dominate the planet.
"Homo sapien" literally means "wise man" but perhaps it is our imagination which truly makes us unique.
