It was a warm autumn day in Los Angeles when I sat down on a bench opposite a male orangutan. A thick pane of plastic separated us. From an outsider's perspective, we could not have been more different. Two mature male apes, one with minimal body hair covered with clothes, the other with long, bright strands of orange fur. We each have a pair of opposable thumbs, but he also has opposable big toes, which helps him climb trees and grasp branches. I speak English. He grunts.

But were we really so different? As we considered each other, separated by just 16 inches and 16 million years of evolution, I couldn't help but see something familiar. Looking into his face was like looking into a funhouse mirror. What was reflected back at me wasn't a perfect replication of my own image, but it wasn't all that different either. Each of us was a slightly distorted version of the other.

We humans have always thought of ourselves as distinct from the rest of nature. Discovering that the solar system did not revolve around our planet seriously challenged the notion that humanity was the pinnacle of creation, the raison d'etre of the cosmos. "Our species had a collective freak-out when we realised we weren't special astronomically," says Laurie Santos, a primatologist at Yale University. And so, after the Copernican Revolution we set off in search of new ways in which we might be of paramount importance. Perhaps our planet wasn't central to the universe, but surely humanity was central to our planet?

More than 400 years later, a young primatologist named Jane Goodall arrived in what was then called the Gombe Stream Game Reserve in Tanzania. When she first sat down on a hilltop to watch the chimpanzees, people thought that humans were the only species that used tools. In those first few years at Gombe, however, Goodall's work would throw humans off their pedestal yet again.

"During three years in the Gombe Stream Chimpanzee Reserve in Tanganyika, East Africa," she wrote in a paper in the journal Nature, "I saw chimpanzees use natural objects as tools on many occasions. These objects consisted of sticks, stalks, stems and twigs, which were used mainly in connexion with eating insects, and leaves which were used as 'drinking tools' and for wiping various parts of the body." 

One of the primary uses for sticks was to fish for termites. The stick was first plunged into a termite mound, and when the chimp pulled it out, it was covered with tasty insects, ready to be licked off like ice cream from a cone. But not just any stick would do; if one was too long, they would break it into pieces of appropriate length. Some particularly crafty chimps figured out how to use sticks to pry open boxes filled with bananas.

The legend goes that when Goodall phoned her mentor Louis Leakey with news of her exciting discovery he wrote, "We must now redefine man, redefine tool, or accept chimpanzees as human." 

“We humans have always thought of ourselves as distinct from the rest of nature.”

Emory University professor of primate behaviour Frans de Waal, who is also the director of Living Links at the Yerkes National Primate Research Center, told me that the human mind is like an iceberg. The part that is perhaps unique to our species is just the tiny bit sticking up out of the water. 

Therefore, most of the distinctions between humans and other animals are a matter of degree rather than kind. They are quantitative, not qualitative. Meerkats teach, but they only teach their young how to safely kill scorpions, one of their primary sources of food. Humans, on the other hand, will teach just about anything. 

Chimpanzees, elephants, dolphins and killer whales all have basic forms of culture. For instance, each troop of chimpanzees has its own way of cracking nuts open. Humans, on the other hand, have cumulative culture. Each generation builds upon the cultural innovations and technologies of previous generations.

"We build ships now very differently than ships were built a thousand years ago, and that's because there's been this increasing addition and modification of cultural knowledge," says Katie Hinde, an evolutionary biologist at Harvard University. "Our technology and our cultural practices are continuously changing, additively, across time. That right there is one of the key unique features of humans," she adds.

Hinde also argues that what marks humans as distinctive is the degree to which we are willing to work together. "We cooperate at a scale no other animal is capable of. We can meet an individual from the other side of the world and not know the same language, but find ways to communicate and coordinate such that we [can] engage in a cooperative task together,” she says.

As with culture, this too is a quantitative distinction rather than a categorical one. Primates and cetaceans can easily work together and wolves hunt cooperatively, but their partnerships are founded upon familiarity or relatedness. Friends and family are in, but strangers are out.

For Santos, the thing that defines humanity is our ability to get out of our own heads, to escape the immediate present and consider the past or future. That too is not entirely unique to humans, but the ability of a scrub jay to cache food for future use is not nearly as sophisticated as our variety of future planning. Though that ability, she thinks, is a double-edged sword. "It also generally means that we lack the contentment that simply being in the here and now brings," Santos says. "It's why macaques don't need meditation, and why cows don't lose sleep ruminating about whether their kids are going to be okay in life."

Chimpanzee Intelligence 2014 09 11
Chimpanzees and other great apes are known for their intelligence - spending time watching them can make us realise how 'un-special' we really are. Image: Tambako The Jaguar, Flickr

As it turns out, every time we think we have identified something that is unique to our species, careful observation of other animals reveals that it is not. Herring gulls play games, cockatoos dance to the beat of a song and elephants mourn their dead. Chimpanzees go to war, bonobos have sex face to face and domestic dogs want to be treated fairly.

"It's a strange obsession in my opinion," de Waal says of our unending drive to define ourselves as exceptional. Though that obsession, he speculates, may have arisen out of the particular landscape in which Western cultures evolved. "The [Judeo-Christian] idea that we are special and we have souls and animals are totally different is partly a product, I think, of the fauna that surrounded us when these religions arose."

The Abrahamic cultures – Judaism, Christianity, Islam – arose in the Middle Eastern desert, a landscape that provided little connection to other primates. "Most of the animals they were dealing with were goats and snakes and camels, [and] it was very easy to maintain the position that we humans were totally different from other animals," says de Waal. Eastern cultures, on the other hand, developed in places surrounded by primates. "Japan has monkeys, China has monkeys, India has lots of monkeys."

That pattern persists even today in our fairy tales and folklore. "In the West, it's all foxes and ravens and wolves. Our narration about our connection with the animal kingdom is quite different," de Waal explains, than that of the eastern world. Faced with other primates, it is harder to maintain our sense of superiority. Perhaps if more people could spend some time watching chimpanzees or bonobos, they too would realise how 'un-special' we really are. 

Faced with other primates, it is harder to maintain our sense of superiority. Indeed, when the first apes began to appear in zoos in London and Paris in the early 19th century, Charles Darwin was delighted, but many people had a very strong negative reaction, including the Queen.

"Why would you be disgusted by a primate? The only reason I can think of is that Queen Victoria and everybody else in that time, they had this image that we humans were absolutely special and unique," de Waal says. "And now they were confronted by a creature that was called an animal and [yet] looked so extremely similar in many ways to us. It made you question if perhaps we were also animals."

What shall we make of the irony that humans are repulsed by our own animal nature? Maybe it’s just a human thing.

Top header image: Tambako The Jaguar, Flickr