When they talk about culture, most people mean human things like art, music, and clothing styles. But in tomorrow's Nature, a group of researchers who have spend years observing chimpanzees in the wild proposes that chimps have culture too. Each chimpanzee group they have studied has a distinctive set of behaviors, including tool use and social habits, which is passed on from generation to generation.
Several primatologists have proposed that differences in the way different groups of chimps fish for ants, for example, are examples of cultural behavior. But most comparisons of chimp behavior were based on reviews of the published literature and are incomplete. Hoping to put together a comprehensive list of possible cultural variations, psychologist Andrew Whiten of the Scottish Primate Research Group at the University of St. Andrews in Scotland asked team leaders from the six longest running studies of wild chimps across equatorial Africa to make a list of all the behaviors seen at their sites. The researchers took note of environmental differences that might influence behavior, such as predators and available plant species, and indicated whether a behavior was observed only occasionally, or whether it was common in the group.
In the end, the scientists found 39 behaviors that are customary or habitual in one group, but absent in other groups that live in similar surroundings. For example, the favorite food of some chimpanzee colonies is nutritious oil palm nuts, which the animals skillfully crack open with rocks. But other groups ignore the nuts, even though both nuts and rocks are readily available. There are etiquette differences too: Several groups clasp each others' hands above their heads during grooming, a tradition that has never been witnessed in other groups.
Of course, the most complex behavior ever witnessed in chimpanzees is a far cry from what human societies can accomplish. Chimpanzees don't seem to be able to build on previous inventions the way humans can, notes psychologist Bennett Galef of McMaster University in Hamilton, Ontario, who believes it's premature to ascribe culture to nonhuman primates. But other researchers argue that the cultural stirrings seen in our primate cousins may help uncover the roots of our complex human behaviors.