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Sept. 5, 2006
Chimps pass cultural behavior to multiple generations

By Stephanie Mcnicoll

Transferring knowledge through a chain of generations is a behavior not exclusive to humans, according to new findings by researchers at the Yerkes National Primate Research Center of Emory University and the University of St. Andrews, Scotland.

For the first time, researchers have shown, that chimpanzees exhibit generational learning behavior similar to that in humans. Unlike previous findings that indicated chimpanzees simply conform to the social norms of the group, this study reveals behavior and traditions can be passed along a chain of individual chimpanzees. These findings, based upon behavioral data gathered at the Yerkes Field Station in Lawrenceville, Ga., were published online in the Aug. 28 early edition of the Proceedings of the National Academy of Sciences.

Using a research design that simulated transmission over multiple generations, Yerkes and University of St. Andrews researchers were able to more closely examine how chimpanzees learn from each other and the potential longevity of their culture. In doing so, they confirmed that a particular behavior can be transmitted accurately along a chain of up to six chimpanzees, representing six simulated generations, equaling approximately 90 years of culture in the wild.

A comparative benchmark study with three-year-old human children, conducted by a St. Andrews researcher, revealed similar results, providing further evidence that chimpanzees, like humans, are creatures of culture.

In the chimp study, researchers began by introducing a foraging technique to two chimpanzees, each from two separate social groups, to train them to open a special testing box, either by sliding or lifting the door to reveal fruit inside. Chimpanzees in a third social group, used as the control group, were allowed to explore the testing box but were given no instruction or training on how to open it. Once each chimp from the first two social groups proved successful, another chimp from the same social group was allowed to observe the process before interacting with the testing box. Once the second chimp succeeded, another would enter and observe the technique, and so on down the chain. In the two social groups trained to slide or lift the door, the technique used by the original animal was passed to up to six chimpanzees.

“The chimpanzees in this study continued using only the technique they observed rather than an alternative method,” said Victoria Horner, associate researcher at Yerkes. “This finding is particularly remarkable considering the chimpanzees in the control group were able, to discover both methods through individual exploration. Clearly, observing one exclusive technique from a previous chimpanzee was sufficient for transmission of behavior along multiple cultural generations.”

This research may contribute to a better understanding of how chimpanzees learn complex behaviors in the wild. “These findings also show great similarity between human and chimpanzee behavior, suggesting cultural learning may be rooted deep within the evolutionary process,”
said Horner.

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