WORLD SCIENCE

"Long before it's in the papers"
December 19, 2005

Aug. 22, 2005
Courtesy Nature
and World Science staff

Social conformity—a desire to act, talk, dress and even think like everyone else—is a human tendency that has helped glue societies together for ages, while perennially irritating some of the greatest thinkers, scientists and artists.

Wild chimpanzees use tools to get food. Researchers say the animals tend to follow the example of a group leader in choosing how to use tools. (Credit: David Bygott)

A chimpanzee watches her mother use the poke method on the Pan-pipes. (Drawing by Amy Whiten).

Now, researchers have found we share this monkey-see-monkey-do mindset with—perhaps unsurprisingly—chimps. This shows conformity has deep evolutionary roots, the researchers claim. 

The findings, by U.S. and British scientists, are published in the current online edition of the research journal Nature.

During the study, three groups of chimps at the Yerkes National Primate Research Center of Emory University in Atlanta, Ga., were presented with a problem also known to their wild cousins: some enticing food was stuck just out of reach, behind a blockage. 

This was achieved by a system of tubes the researchers called the Pan-pipes. 

Unseen by their group-mates, one chimp from each of two of the groups was shown a different way to use a stick to retrieve the food. One was taught to use the tool to lift the blockage up so the food fell towards her. The other was trained instead to poke the blockage, pushing it so the food fell backwards and rolled down another pipe into her waiting hand.

These two chimps, who were high-ranking members of their groups, were then reunited with their respective groups, the researchers recounted. They soon started to apply their newly-learned techniques to the Pan-pipes task. 

The researchers said they wanted to find out whether the other chimps would learn by observation the technique used by their local expert, and thus establish different traditions in the two groups. 

“Chimpanzees in the wild show numerous local traditions described as ‘ape culture,’” said Andrew Whiten of the University of St. Andrews in Fife, U.K, one of the researchers. “But it is almost impossible to prove that these traditions are actually passed on by each chimpanzee learning from others,” as is the case with humans. “It is hard to do the necessary experiments with wild chimpanzees.”

The chimps in the experiment proved keen learners, according to the scientists. Members of the chimp groups gathered around their local experts, watched attentively and learned the technique. 

But this wasn’t true of the third group of chimps, which didn’t have the benefit of a local expert and was left to solve the task on its own. Its members couldn’t retrieve food from the pipes. 

In contrast, in the first experimental group the expert’s “lift” technique was soon adopted, while the “poke” method spread in the second group, the scientists said. When tested two months later, this difference in group traditions persisted, the researchers found. This is the first experimental evidence for the spread and maintenance of traditions in any primate, they claimed.

Chimps “copy members of their own species and they develop different traditions by doing so,” said the university’s Victoria Horner, another of the researchers. “It makes it likely differences in tool use between wild chimpanzee communities in Africa indeed reflect a form of culture and establishes another link between human and chimpanzee societies.”

A few members of each group independently discovered the alternative method for freeing food from the Pan-pipes, the researchers said. But this knowledge didn’t change group traditions: most of these chimps reverted to the norm set by their local expert. “Choosing the group norm over the alternative method shows a level of conformity we usually associate only with our own species,” said Horner. 

“These results suggest an ancient origin for the cultural conformism that is so evident in humans,” said Emory University’s Frans de Waal, another member of the research team. “Further research may reveal this tendency to be more widespread in the animal kingdom.”

The findings aren’t the only recent research to find unexpected commonalities between human and primate societies. These commonalities sometimes involve cultural tendencies that some of us view with contempt. 

For instance, one recent study concluded that monkeys may have a version of “celebrity-gazing” evident in humans. Monkeys in that study were found to prefer looking at higher-ranking members of their group, rather than lower-ranking ones. Interestingly, in the conformity study, the chimp chosen to be each group’s expert was a high-ranking female.

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