for National Geographic News
An international group of scientists pooling more than 30 years of data has concluded that behavioral patterns among different orangutan populations show evidence of culture.
The finding pushes the origins of culture among great apes back to 14 million years ago, when orangutans and African apes last had a common ancestor. Great apes include orangutans, found only in Asia, and Africa's gorillas and chimpanzees.
Earlier studies had shown evidence of cultural learning among chimpanzees, suggesting that great ape culture had been around for at least five to seven million years. Transmission of cultural knowledge in orangutans and other great apes has implications for understanding the evolution of human culture.
Culture, which can be defined as the presence of geographically distinct behavioral variants that are maintained and transmitted through social learning, was long considered to be a uniquely human trait.
"What this study shows is that the great apes have a solid foundation of their own culture, on which humans erected their own," said Carel van Schaik, a professor of biological anthropology and anatomy at Duke University.
"This study demonstrates the richness of orangutan behavior and how the study of orangutans is important for understanding human evolution," said Cheryl Knott, an anthropologist at Harvard University and a co-author of the study. "But our ability to study and learn from these fascinating creatures is vanishing as these forests rapidly disappear with the whirr of the chainsaw."
To be considered cultural elements, behaviors and practices must vary from region to region, be more common where there is more social contact within a group, and not depend on habitat.
Studying six populations of orangutans in Borneo and Sumatra, Indonesia, researchers identified 24 behaviors that show evidence of being culturally transmitted. Many of the behaviors involve tool useusing sticks to dig seeds out of fruit, to poke into tree holes to obtain insects, or to scratchor using leaves as napkins or as gloves to protect against spiny fruit.
The authors, writing in the January 3 issue of the journal Science, suggest that variations on these behaviors found among the different populations are cultural. For instance, some populations made sounds such as "raspberries" or "kiss-squeaks" using leaves to amplify the sound, others used flat hands, others balled their hands into trumpet-like fists. Among some populations the behavior was rare or absent.
Other traits that show evidence of cultural transmission include different forms of communication and play.
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