Whether it's using leaves to daintily dab at food dripping from their chins or saying goodnight with loud, squeaky kisses, orangutans appear to have culture -- learned behavioral innovations that spread among social groups and to succeeding generations.
Once thought to be the hallmark of man, cultural transmission has been detected in chimps, which evolved 7 million years ago. The discovery in orangutans pushes back the origins of culture to 14 million years ago, when the more primitive orangutans evolved.
"All these findings suggest that the first ancestral man-apes must have had a pretty solid evolutionary cultural foundation on which to build," said Carel van Schaik of Duke University, the lead author on a paper describing orangutan culture in Thursday's issue of Science.
The conclusion was the work of nine primatologists who examined videos and behavioral notes from different orangutan groups and determined that there were 24 types of behavior that could be classified as cultural and that had not spread between different orangutan bands.
Behaviors included the use of leafy branches as flyswatters, riding falling dead trees to the ground for sport, building sun and rain covers over nests and using leaves as protective gloves when handling spiny branches.
As for the goodnight kiss squeaks, some orangutans use their hands to change the sound. Others used leaves to amplify the noise.
Researchers said the finding is even more justification to protect the ape species. An estimated 90% of the animals have disappeared because of habitat destruction and logging in their habitats on the Indonesian islands of Sumatra and Borneo. Researchers say there are just 15,000 to 20,000 of the animals left in the wild.