Yerkes-based Experiment Confirms Cultural Transmission And Conformity In Chimpanzee Communities

Unlike previous studies that used human models for cultural-learningexperiments with chimpanzees, researchers Victoria Horner, PhD, andFrans B. M. de Waal, PhD, of the Living Links Center at the YerkesResearch Center, and Andrew Whiten, PhD, of the University of St.Andrews, Scotland, applied a unique method that extends theexperimental approach to the group

level, focuses on ape-to-ape transmission and uses atwo-action methodology. This approach bridges the gap between twoconventional research methods: population-level observations on wildapes and one-to-one social learning experiments.

In the study, researchers introduced a naturalistic foragingtask into three groups (two experimental and one control) to see ifchimpanzees can learn by observation. While unseen by otherchimpanzees, researchers taught a high-ranking female from each of thetwo experimental groups a different way, either Lift or Poke, toretrieve food from a system of tubes called Pan-pipes. Once the twofemales mastered the task, other chimpanzees within their groups wereallowed to watch them perform the new skill over a seven-day periodbefore all group members were allowed to use the tool. According to theresearchers, group members gathered around the local expert, watchedattentively and proved successful when allowed to try the task on theirown. The third group, which did not have the benefit of a local expertand was left to decipher the task on its own, was unsuccessful inretrieving food from the Pan-pipes.

"This study demonstrates apes do copy members of their ownspecies and they develop different traditions by doing so," said Dr.Horner. "It makes it likely differences in tool use between wildchimpanzee communities in Africa indeed reflect a form of culture andestablishes another link between human and chimpanzee societies."

The conformity bias finding was an unexpected, but equallyimportant, result of this culture study, according to Dr. Horner. A fewmembers of each group independently discovered the alternative methodfor freeing food from the Pan-pipes, but this knowledge did notendanger the groups' traditions because most of these chimpanzeesreverted back to the norm set by their local expert. "Choosing thegroup norm over the alternative method shows a level of conformity weusually associate only with our own species," said Dr. Horner. "Byusing the group's technique rather than the alternative method, we seethe conformity is based more on a social bond with other group membersthan the simple reward of freeing the food."

A characteristic traditionally thought to be solely human, thepropensity to conform, may be part of an evolutionary progression."These results suggest an ancient origin for the cultural conformismthat is so evident in humans," said de Waal. "Further research mayreveal these findings to be more widespread throughout the animalkingdom."

The Yerkes National Primate Research Center of Emory University isone of eight national primate research centers funded by the NationalInstitutes of Health. The Yerkes Research Center is a recognized leaderfor its biomedical and behavioral studies with nonhuman primates, whichprovide a critical link between research with small laboratory animalsand the clinical trials performed in humans. Yerkes researchers are onthe forefront of developing vaccines for AIDS and malaria, andtreatments for cocaine addiction and Parkinson's disease. Yerkesresearchers also are leading programs to better understand the agingprocess, pioneer organ transplant procedures and provide safer drugs toorgan transplant recipients, determine the behavioral effects ofhormone replacement therapy, prevent early onset vision disorders andshed light on human behavioral evolution.

Note: Additional resources for readers include:http://www.emory.edu/LIVING_LINKS/ --ape and human evolution information
http://www.nature.com/news --an interactive chimpanzee-related quiz (Portions of the quiz material were provided by the Yerkes Research Center.)