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Orangutans swinging culture revealed

19:00 02 January 03

Natasha McDowell

Orangutans have culture, reveals a new study combining decades of observations. Its existence suggests that the basis of human culture originated much earlier than previously thought.

The international team of scientists, led by Carel van Schaik of Duke University, North Carolina, found 24 orangutan behaviours that are passed on by imitation, a hallmark of culture. This pushes the origins of culturally transmitted behaviour back to 14 million years ago, when orangutans first evolved from their more primitive primate ancestors.

 

Some of the behaviours are practical, such as poking sticks into trees to gather insects, but others appear to be just plain fun. Some orangutan groups blow "raspberries" as they bed down for the night, the equivalent of our "night-night". Others indulge in "snag-riding", the sport of surfing falling dead trees and then grabbing surrounding vegetation just before hitting the ground.

The fact that some orangutans used tools while others did not prompted the collaboration to search for evidence of culture. But the researchers had not been sure they would it. "We were all rather giddy when we realised what had come out of our data," says van Schaik.

Chimps, whale and dolphins

The work follows an earlier study revealing chimpanzee culture (Nature, vol 399, p 682), which also combined many decades of observations. This suggested 39 cultural behaviours for chimps and therefore set the origin of cultural traits in primates at seven million years.

Scientists suspect cultural behaviour arose before chimps, orangutans and humans diverged because it is less likely that it arose three times independently.

Orangutans are the least related to humans of all the great apes, so if the origins of human culture is to be pushed back even further, researchers will have to start looking at other primates like monkeys, or even at whales or dolphins, says Andrew Whiten, at St Andrew's University, UK, who led the earlier chimpanzee study.

Some research suggests that whales and dolphins, large-brained and social animals that also live in ecological niches, may show cultural behaviours.

Social contact

Culture requires extensive social contact in order for the behaviours to be passed on. But unlike their more friendly chimpanzee counterparts, orangutans tend to be more solitary.

However, some orangutan groupings are more sociable than others, and these groups showed more of the identified behaviours, strengthening the argument that they are cultural.

Another concern was that the behavioural differences may be due simply to the apes adapting to different habitats. But the traits the researchers observed varied from region to region and did not depend on habitat. "It shows we are dealing with culture, not an artefact of ecology," says van Schaik.

The discovery may help us understand the roots of human culture. By showing how similar chimps and orangutans cultures are, he says, we can look at how they differ to human culture and ask what causes the differences.

But just as the study of orangutans is giving a handle on human culture, the apes are disappearing. Some of the areas included in the study have already been lost to illegal logging. "We are in a race against time," says van Schaik.

Journal reference: Science (vol 299, p 102)

19:00 02 January 03