A comparison of orangutan social groups shows that the animals have at least some hallmarks of what in humans is commonly called culture. In the 3 January issue of Science, researchers describe two dozen behaviors that are present in some groups and absent in others. The practices are apparently learned from other group members and passed from generation to generation. Such observations give biologists richer insights into animal behavior, others say, and might help researchers learn more about the roots of human culture by clarifying what makes it distinctive.
For many years, culture was thought to be unique to the human species, but evidence has been growing for socially learned traditions elsewhere in the animal kingdom. In 1999, chimpanzee researchers reported 39 examples of behaviors that were specific to particular groups and did not seem to be determined by the environment (Science, 25 June 1999, p. 2070).
Primatologist Carel van Schaik of Duke University in Durham, North Carolina, suspected that a similar pattern might be present in orangutans. In the Suaq Balimbing forest in Sumatra, for instance, he and his colleagues had observed these animals using sticks to extract seeds from the Neesia fruit. In Borneo, however, other researchers never see such handiwork, even though Neesia is readily available. Curious to see if orangutan researchers could come up with a list of behaviors similar to that compiled by chimpanzee researchers, van Schaik invited his colleagues to a 3-day meeting to compare notes.
As the researchers compared notes--and videotapes when possible--it became clear that many behaviors were strikingly different between orangutan groups. The list of probable cultural traits is not as long as that for chimpanzees, but orangutans' tendency to interact with their neighbors less than chimps do made the pattern of learning even clearer. The researchers found that groups of more sociable orangutans had larger behavioral repertoires than groups of relatively solitary individuals had, supporting the theory that social contact spreads cultural behaviors.
The study is only a beginning, cautions psychologist Michael Tomasello of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Researchers "talking about their impressions is an excellent way to generate hypotheses, but it's only step one," he says. Van Schaik agrees that he and his colleagues now need to return to the field with the full list of behaviors to verify that they're present in some groups and not in others.
Related sites
Van
Schaik's Science paper
Van
Schaik's site
)
)
)
)
)
)
)
)
)
)
)
