Chimpanzees sometimes work together to solve problems. But scientists haven't been sure whether chimps deliberately cooperate to reach a common goal, or accidentally do it by focusing on related tasks. Now, we have evidence that they are consciously working to form teams. This sheds light on the social behavior of chimps and humans alike.


Unraveling mechanisms of cooperation in the animal kingdom can be tricky. After all, plenty of species coordinate to achieve mutually beneficial outcomes. One of my favorite examples of this is this aerial footage of African wild dogs tracking prey with Seal Team 6 levels of precision. If you watch it, you'll find it obvious that the dogs are cooperating. What's less clear is the level of intentional collaboration at work – to what degree do these dogs understand the need to help one another acquire prey? Speaking more broadly, how do we know animals that cooperate aren't just acting independently toward a common goal, oblivious to the various roles of their fellow "teammates"?

Questions like these are central to understanding animal behavior, but they also speak to humanity's place in the animal kingdom at large. "Cooperation makes us a really successful species," says behavioral scientist Alicia Melis in an interview with io9. That we actively recognize how a teammate's efforts can complement our own suggests we understand cooperation in ways other animals may not. But when did we evolve this insight, and are there any other species who possess it?


Melis believes chimpanzees could hold vital clues to these and other questions. With this in mind, she has been investigating teamwork in chimps for years. "It's a fascinating topic," she says, "because cooperation is the basis of all human societies and cultures." Understanding the similarities between humanity's collaborative skills and those of our closest primate relatives, she says, is crucial – not just to unraveling the mechanisms at play in the behavior of chimps, but in humans, as well.

In a study recounted in the latest issue of Biology Letters, Melis and her colleague Michael Tomasello – a psychologist and co-director of the Max Planck Institute for Evolutionary Anthropology – conducted a series of experiments to examine the mechanisms at work in chimpanzee collaboration.

The study involved a total of 12 chimps, who were paired off into teams. Each team was presented with a box, inside of which was a tasty reward in the form of grapes. But getting at the grapes was tricky.


Each box housed a grape-dispensing mechanism that required the use of two non-interchangeable tools. From the back of the box, one chimp would move grapes into position with the use of a rake, while the chimp facing the front of the box inserted a stick to trigger the release of any grapes pushed into position by its partner. Retrieving the grapes therefore required the chimps to not only assume complementary roles, but aid one another in performing those roles.

The researchers complicated things further by giving both tools to one chimp at a time. The chimp therefore needed to not only share one of its tools, but the right tool, in order to get at the grapes. Ten out of the 12 chimps solved the task, and tool-sharing occurred 97% of the time. More impressive still: three quarters of the time, they gave their partner the correct tool. This, says Melis, was surprising. "It shows that they are thinking about the two roles and how they are interrelated more than we thought they would... [but] that is what they did!"


The study, Melis says, provides the first evidence that chimps can pay attention to a partner's actions in a collaborative task, "and shows they know their partner not only has to be there but perform a specific role if they are to succeed."

"It shows they can work strategically together just like humans do, working out that they not only need to work together but what roles each chimpanzee has to do in order to succeed."


So what does this have to do with human cooperation? Chimpanzees and humans share a common ancestor. That chimps are capable of such sophisticated levels of understanding when it comes to teamwork therefore suggests that our ability to collaborate intentionally may have originated in our mutual evolutionary forebear. Whether this is actually the case, says Melis, will require more research.

"If we found this same capacity in bonobos [a great ape that shares as much DNA with humans as its more aggressive cousin, the chimpanzee]" she explains, "then maybe we could say with more confidence that this is an ability that evolved before the 2 lineages [Pan and Homo] separated."


The researchers' findings are published in the latest issue of Biology Letters.