Chimpanzees ape their peers
Humans are not alone in being overly swayed by what everybody else does, according to new research on chimpanzees.
Children may copy the habits of their parents and teenagers are desperate to be like their friends, but researchers have now found that chimpanzees share the same conformist desire.
The new study, by leading primate experts at the University of St Andrews and Atlanta’s Emory University, demonstrates that apes have developed different traditions by copying members of their own species. An international collaboration led by St Andrews researchers in 1999 suggested that chimpanzees lead a rich cultural life with different traditions unique to each community, but until now it has been impossible to determine how apes pass on these traditions.
Now it is known that not only do apes reflects a complexity of cultural variation unmatched by species other than our own, but they demonstrate a bias towards social conformity which is regarded as a hallmark of human culture.
During the study, researchers have – for the first time – artificially spread different habits in different chimpanzee groups by presenting two different groups with the same problem but different solutions. The chimpanzees, at the Yerkes National Primate Research Center of Emory University, were presented with a problem also known to their wild cousins: a tasty food item was stuck just out of reach, behind a blockage; a system of tubes the researchers called ‘Pan-pipes’.
One chimpanzee from each group was shown a different way to use a stick to retrieve the food. Ericka was taught to use the tool to lift the blockage up so the food fell towards her, while Georgia was trained instead to poke the blockage, pushing it so the food fell backwards and rolled down another pipe into her waiting hand.
Ericka and Georgia were then reunited with their respective groups and soon started to apply their newly-learned techniques to the Pan-pipes task. The researchers, Professor Andrew Whiten and Dr Victoria Horner from the University of St Andrews and Professor Frans de Waal of Emory University, wanted to discover whether the other chimpanzees would learn by observation the technique used by their local expert, and thus establish different traditions in the two groups.
Professor Whiten explained: “Chimpanzees in the wild show numerous local traditions described as ‘ape culture’, but it is almost impossible to prove that these traditions are actually passed on by each chimpanzee learning from others, as is the case in human culture. It is hard to do the necessary experiments with wild chimpanzees.”
“The present study demonstrates that apes do copy members of their own species, and that they can develop different traditions by doing so,” said Dr Horner.
In fact Ericka and Georgia’s companions proved keen learners. They gathered around their group expert, watching attentively, and when they got their own turn at the Pan-pipes, they were soon successful. In this they were quite different from a third set of chimpanzees who were offered the Pan-pipes without the benefit of an expert model. The problem proved too hard for any of these naïve chimpanzees to solve. In contrast, in the first experimental group Georgia’s ‘poke’ technique was soon adopted, while Ericka’s ‘lift’ method spread in the second group. When tested two months later, this difference in group traditions was still in place.
This is the first experimental evidence for the spread and maintenance of traditions in any primate. It makes it likely that differences in tool use between wild chimpanzee communities in Africa indeed reflect a simple form of culture.
An unexpected and intriguing finding of the study followed after a few chimpanzees in each group discovered the alternative method. In Ericka’s ‘lift’ group in particular, several chimpanzees independently discovered the poke method. But this did not endanger the groups’ traditions, because individuals tended to revert back to the norm of their group.
“This was a surprise to all of us”, said Professor Whiten, “knowing the alternative method yet still converging on the group norm shows a level of conformity we usually associate only with our own species. This is assumed to reflect humans’ special cultural nature, and its existence in chimpanzees suggests that their much simpler form of culture has nevertheless left its mark on their social psychology.”
“These results suggest an ancient origin for the cultural conformism that is so evident in humans,” concluded Professor de Waal. “Further research may reveal this tendency to be more widespread in the animal kingdom.”
The study, published today by the scientific journal Nature, was supported by a grant from the UK’s biological research council (BBSRC) and by the Living Links Center at Emory.
NOTE TO EDITORS:
The research paper ‘Conformity to cultural norms of tool use in chimpanzees’ by Professor Andrew Whiten, Dr Victoria Horner and Professor Frans de Waal is published as an Advanced Online Publication by Nature, doi:10. 1038/nature04047. It will appear in print in a later issue.
The current online article (www.nature.com) is accompanied by supplementary information and video clips showing human demonstration of the Pan-pipes. Further video clips of chimpanzees’ operation of the Pan- pipes will appear on the Nature website next week.
BIOGRAPHICAL INFORMATION ABOUT RESEARCHERS:
Andrew Whiten, a Fellow of the British Academy and of the Royal Society of Edinburgh, is Professor of Evolutionary and Developmental Psychology and Wardlaw Professor of Psychology at the University of St Andrews. He was the lead author of an earlier publication in Nature that presented evidence for the existence of 39 cultural variants among wild chimpanzees: – For more information see Professor Whiten’s personal web pages at: http://psy.st- andrews.ac.uk/people/lect/aw2
Dr Victoria Horner is a post- doctoral BBSRC research associate in the School of Psychology at the University of St Andrews and an associate researcher at the Living Links Center of the Yerkes National Primate Research Center, Emory University. Like Whiten, she is a member of the Scottish Primate Research Group. Dr Horner’s previous study was of observational learning in juvenile chimpanzees at the Ngamba Island sanctuary in Lake Victoria, Uganda. A report of this work has just been published: – Horner, V. & Whiten, A. (2005). Causal knowledge and imitation/emulation switching in chimpanzees (Pan troglodytes) and children (Homo sapiens). Animal Cognition, 8, 164-181. Doi 10.1007/s10071-004-0239-6.
Frans de Waal is C. H. Candler Professor of Primate Behavior at Emory University and Director of the Living Links Center, Yerkes National Primate Research Center, Emory University, Atlanta. He is the author of ‘The Ape and the Sushi Master: Cultural Reflections of a Primatologist’ (2001) and ‘Our Inner Ape’ (2005). He was elected to the (US) National Academy of Sciences, in 2004. For more information see: http://www.emory.edu/LIVING_LINKS/
THE RESEARCHERS ARE AVAILABLE FOR INTERVIEW:
PROFESSOR WHITEN – Tel. (UK) 01334 462073 DR HORNER – Tel. (USA) 404 727 9071
PROFESSOR DE WAAL – email: email@example.com
IMAGES ARE AVAILABLE – CONTACT THE ST ANDREWS PRESS OFFICE ON 01334 462529 / 7227
IMAGE 1, TOOL USE – Tool use in wild chimpanzees. Chimpanzees using plant stems to dip for ants at a nest hole. The new experimental research supports the idea that variations in such behaviour across Africa result from chimpanzees conforming to local traditions (required credit photo by David Bygott).
IMAGE 2, POKE METHOD – Chimpanzee Georgia watches her mother, Borie, use the poke method on the Pan- pipes. This technique spread in Borie and Georgia’s group, while the alternative lift method spread in another group where a different chimpanzee was trained to start using the lift method instead. (required credit: Photograph by Frans de Waal).
SKETCH 1, POKE METHOD – As above (required credit drawing by Amy Whiten).
SKETCH 2, LIFT METHOD – Observing the lift technique (required credit drawing by Amy Whiten).
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