The findings support the idea that chimps conform to social traditions passed on between members of the same clan, the first time this has been found outside human societies.
The research could provide insights into why people like to follow their peer group, whether they are adolescents who take up smoking or the followers of a fashion. Although it has long been known that chimps can learn how to do new things by watching other members of the same group, the idea that they prefer to do one thing just because their colleagues are doing it is new. The study supports recent observations of chimps in the wild which showed they have extensive cultural traditions, although it has been impossible to prove these are passed on by each chimp learning from others, as with human culture.
The latest findings come from an experiment by primatologists working with chimps in captivity at the Yerkes National Primate Research Centre at Emory University in Atlanta, Georgia. Two high-ranking female chimps, Erika and Georgia, were trained to extract tasty morsels of food from a blocked pipe-like device while they were kept out of sight of their peer group.
Georgia was taught to get the food with a stick she used to poke the blockage backwards along the pipe, which caused the food to roll back a little before it fell down a chute and into her hand. Erika was taught to use her stick to lift the blockage up, which allowed the food to roll forward for collection from the chute.
When each chimp was put back with other members of their group they quickly demonstrated to the others how to reach the food using the technique each had been taught.
Professor Andrew Whiten of St Andrew University, who led the study, published in the journal Nature, said members of Georgia's group independently learnt how to extract the food using Erika's technique and vice versa for Erika's group. But the new extraction trick was quickly abandoned, with the "inventors" reverting back to the norms of their group, clearly conforming to tradition.