Orangutans, those red-haired, knuckle-dragging apes, are loping today into the upper echelons of the hominid hierarchy. According to research reported in the journal Science, they exhibit what was until very recently considered a uniquely human attribute: culture.
Orangutans Said to Exhibit Hallmarks of CultureBy CAROL KAESUK YOON
Drawing on decades of research and hundreds of thousands of hours of observations from six different sites in the wild, an international team of scientists found evidence that orangutan groups differ in everything from bedtime rituals to eating habits to sexual practices - patterns of behavior, passed from generation to generation, that scientists call culture.
Other researchers reported four years ago that chimpanzees differ in the way they groom one another, hunt and eat ants and so on. Scientists say the new work suggests that the two remaining great ape species, gorillas and bonobos, are likely to have culture as well and that great ape culture dates back at least to the origin of the entire group 14 million years ago.
The finding has been of particular interest as orangutans have long been thought to be loners, leaving little possibility for the creation of culture. Yet researchers found that at one site all orangutans gave a Bronx cheer before going to sleep, while at other sites this curious ritual was absent. In some forests, orangutans had a characteristic way of hunting and killing a beast known as the slow loris or extracting seeds from the stinging fruit of the Neesia tree. Yet in other forests where the loris and Neesia were found, orangutans never took these meals. And while in two forests, orangutans enjoyed masturbation using sticks, elsewhere such behavior was unheard of.
As is typical whenever scientists aim to award prized attributes of Homo sapiens to other, wilder creatures, there has been heated reaction.
Some point out that while unlikely, it is possible that the orangutans behave differently at different sites because of undetected differences in their forest habitat. Some scientists also object in principle to the use of the heavily freighted term culture, which has long been used to denote something peculiarly human - like wearing white rather than black to funerals, say, or shaking hands rather than kissing as a greeting.
Further research on orangutan culture may be difficult, however, because the species as a whole is threatened as people steadily encroach on its habitats.
But others said that great ape cultures were just the tip of the iceberg.
"In the coming 20 years, we will have a host of studies on culture in all sorts of animals," said Dr. Frans de Waal, primatologist at Emory University, saying data have been coming in suggesting cultural differences among rats, birds and even fish. "We will not think of culture as a monolithic thing, but a concept that includes songbirds, the great apes and human culture."
The study grew out of a workshop that gathered orangutan researchers who had worked for years in isolation from one another at remote field sites on the islands of Borneo and Sumatra, the only places orangutans can be found in the wild.
"You know your own animals and all of them do particular things," said Dr. Carel van Schaik, biological anthropologist at Duke University and lead author on the paper. "So you think all orangutans do these things. Nobody thought there'd be so much variation between the sites."
Dr. van Schaik said there was no evidence of ecological differences or genetic differences that would lead to such differences in behavior. In addition, at sites where orangutans spent more time together there were more of these widespread behaviors, as would be expected with behaviors that can be spread through association. In addition, the closer sites were to one another, the more behaviors those sites shared, again as would be expected.
But Dr. Bennett Galef, animal behaviorist at McMaster University, cautioned that it can be difficult to decipher what is causing differences in behavior among populations in the wild.
For example, in a classic example of chimp culture, chimpanzees are known to use very different methods for extracting ants from ant nests in eastern and western Africa. But in a recent study, researchers reported finding a new group of chimpanzees that will use either method, depending on how aggressive the ant they are hunting is. Dr. Galef said the finding suggests that even this classic chimp cultural divide might have a hidden ecological explanation as simple as the difference in what kinds of ants are available to chimps in different areas.
Most work so far has relied on simply observing animals in the wild. Dr. Galef said the only way to definitively answer many of the key remaining questions will be through experiments in the field.
Unfortunately, researchers say some of the newly uncovered cultures have likely already been destroyed.
Dr. van Schaik said that one site in Sumatra, home of the goodnight Bronx cheer and the hunting of the slow loris, has been devastated over the past several years by an intense wave of illegal logging despite being within a national park. Another of his long-term study sites in Borneo has been devastated by civil war and is still too dangerous to return to.
But even if he were able to go back, Dr. van Schaik said, "probably all the orangutans we knew there are gone."
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