About 5,500 years ago, one group of humans invented something truly revolutionary: the wheel. Almost overnight news of the innovation spread far and wide, and wheels appeared virtually simultaneously in Europe, the Eurasian steppes and the Near East.
In fact, wheels became popular so quickly that some archaeologists say we can’t be sure exactly where the wheel was invented - although Mesopotamia seems like a good bet.
According to Eva Reindl at the University of Birmingham in the UK, stories like this tell us a lot about what makes us human. Surprisingly, it’s not that humans worked out how to make wheels that’s important - it’s the fact that other populations quickly caught on and copied the idea.
Reindl and her colleagues say that other great apes are different. By and large a chimpanzee, gorilla or orangutan won’t copy another ape’s inventions. Each ape, says Reindl, learns for itself how to solve a problem. These species lack our cumulative culture - they are constantly reinventing the wheel.
This raises a question, though. If humans rely so much on a culturally accumulated body of knowledge that they access by imitating others, have we lost the ability to invent our own solutions to basic problems?
When it comes to learning how to crack a tough nut with a wooden tool, for instance, are chimpanzees actually smarter than we are precisely because they know how to experiment for themselves?
Humans and other apes are apparently born in the same state.
Reindl and her colleagues decided to find out. They call our habit of copying others “high-fidelity social learning” – and they say it is so ubiquitous in human societies that trying to find people who haven’t been exposed to it is a challenge. They sidestepped the problem by conducting their experiments with toddlers, who have had relatively little exposure to other humans and less opportunity to imitate human tool use.
They gave the toddlers a series of challenges, which we know wild chimpanzees easy solve with simple wooden tools. One task involved using a stick to crack nuts - replaced by plastic shells in the toddler experiments. Another challenge tested whether the toddlers, like chimps, could use a stick to extract honey from a beehive - although in the experiment the researchers swapped the hive for a plastic tube from which the toddlers could extract paint for drawing.
For almost all challenges, the children passed with flying colours - they completed the tasks as well as a great ape might. Even though our species relies on learning from others, it seems – as youngsters, at least – we’re still capable of thinking entirely for themselves. In this particular domain, humans and other apes are apparently born in the same state.
Cumulative culture is probably uniquely human but it’s a subject of hot debate
Slightly paradoxically, Reidl says that finding similarities in the way humans and other apes are born can actually help us better define what really does make us unique as a species - something that is surprisingly difficult to pin down. This is because it highlights behaviours that we develop but that other apes do not.
For instance, although we might start out life with the same sort of tool-using capability that a chimpanzee possesses, we soon begin to behave in a more sophisticated way - precisely because we watch others and tap into the collective human wisdom that has accrued down the generations.
“My colleagues and I work from the standpoint that cumulative culture is probably uniquely human,” says Riedl. “But it’s a subject of hot debate in the field right now.”
On the other side of the debate are researchers like Christophe Boesch at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. With his colleagues, Boesch has spent a considerable amount of time studying the chimpanzees in the Tai National Park in Ivory Coast.
“Our study of different tool selection in Tai chimpanzees shows clearly that some important social component is at work in how chimpanzee learn to select tools,” he says. In this region, at least, the apes actually do learn some tool use by carefully copying those around them, says Boesch, and this leads to different cumulative cultures in different chimpanzee groups, just as different human societies might have different cumulative cultures.
“We still have so much to learn about tool use in chimpanzees,” says Boesch - including the complete range of tool use behaviours these apes show, how common each behaviour is, and how individual chimpanzees learn to use tools for themselves.
It's not yet clear whether cumulative culture separates us from other apes. The scientific jury clearly hasn’t yet arrived at a decision. When consensus does emerge we’ll know whether our sister species share our ability to imitate others – or whether they are doomed to reinvent the same things over and over again.