We know them as the most highly sexed of all the apes. Now it appears that the easy-going social life enjoyed by bonobos makes them better at cooperating than their more aggressive chimp cousins.
Brian Hare of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and colleagues tested how well chimps and bonobos coped with challenging social situations. Bonobos, they found, were more likely to share a plate of food, using play or sex to defuse social tensions. In contrast, chimps' more limited social skills meant one individual was more likely to take all the food.
The researchers gave pairs of each species a task that required them to work together to retrieve a food reward that neither could reach alone. When the food was easily shared, both species quickly learned to do this. But when the food was in a single bowl - making it easy to monopolise - chimps were less willing to work together (Current Biology, vol 17, p 619).
"It's so simple and obvious that no one's ever demonstrated it," says Hare. "You can't cooperate if you can't share the spoils." The flexibility that allows humans to work together evolved more from social adeptness than high-powered reasoning, he suggests.