Orangutans, long disparaged as prime examples of the brutish ape, are enjoying newfound respect thanks to recent research demonstrating their primitive grasp on a supposedly humans-only possession--culture.
An international team of scientists, led by Duke Professor of Biological Anthropology and Anatomy Carel van Schaik, pored over years of observational research to establish the evidence that orangutans, like humans, acquire patterns of behavior-everything from tool use to sexual technique to bedtime ritual-from being around others in a group, which scientists term culture.
The finding--published in the Jan. 3 issue of Science--sets the beginning of the development of culture to about 14 million years ago, when the human lineage is theorized to have broken off from the orangutans'.
This is not the first time scientists have theorized culture to exist outside humans--previous evidence for chimpanzees, humans' closest living relatives, suggested 7 million years ago as the dawn of culture. Still, the results for orangutans were unexpected.
"It's surprising because [orangutans] are not so social," van Schaik said. "Yet, orangutans and chimpanzees are cultural in very similar ways.... And populations where [orangutans] spent more time together have the greater repertoire of cultural behavior."
For example, orangutans at one site gave each other a Bronx cheer before they went to bed, while elsewhere this practice was absent. Some populations were adept at hunting a rabbit-sized primate called the slow loris; others ignored the meal.
Van Schaik hopes the research will ultimately foster a greater understanding of human culture.
"The value of this study is that we break open the monolithic culture concept," he said. "What we think of as human culture was built on this foundation provided by the great apes. It didn't come de novo out of nowhere."
Van Schaik first noticed orangutan cultural behavior while observing two populations divided by a river and their peculiarly different behavior toward a particular large fruit. One population was proficient at using sticks to pry the fruit's seeds from the prickly protective hairs, but the other group simply ignored the valuable food source. Since the environmental conditions were identical on each side of the river, van Schaik theorized this was evidence of culturally learned behavior, a result he published last year.
Encouraged by the initial observation, van Schaik organized the international team of orangutan experts to find if such behavior extended beyond the one example.
The troop of scientists amassed thousands of hours worth of new and previously recorded data, and organized it in lists and tables, duplicating the methods of the chimpanzee researchers. To ensure the observations were cultural in nature, the researchers eliminated any behavior with obvious environmental correlates and applied numerous tests and qualifying criteria. In one crucial test, behavior was noted to be more similar between groups in closer proximity, indicative of cultural diffusion.
They eventually found 24 separate, socially based orangutan behavior patterns that were varied and eclectic enough to be deemed culture. The scientists further grouped cultural behavior into five broad categories--cues, skills, signals, symbols and institutions--and determined orangutans clearly demonstrated the first three.
"What we've done is mapped more precisely what makes humans different," van Schaik said. "It helps us to break open this concept of culture."
Gwendolyn Borgen, a behavioral data assistant on the project and a graduate student in BAA, agreed with van Schaik on the importance of the study. "We can see, in perspective, the culture of humans and how it's not unique," she said.
Further research will attempt to amplify the current findings by demonstrating cultural behavior in other primate species. "We think it's a great ape universal," van Schaik said.
However, many researchers noted that primate observational studies are being severely compromised by rapidly declining primate populations facing a range of threats, including poaching and rainforest destruction. "We're in a race against time," van Schaik said of the conservation challenge. "They're being clobbered."
The 25,000- to 50,000-strong orangutan population scattered across Borneo and Sumatra has declined about 50 percent over the past decade, mainly due to industrial destruction of their habitat, said Gary Shapiro, vice president of Orangutan Foundation International.
Shapiro expressed hope that the significance of the culture finding will help focus attention on orangutans' plight. "This provides more ammunition for those of us on the conservation side," he said.
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