The transmission of knowledge to the next generation is a key feature of human evolution. In particular, humans tend to copy behaviour that is demonstrated by many other individuals. Chimpanzees and orangutans, two of our closest living relatives, also socially pass on traditional behaviour and culture from one generation to another. Whether and how this process resembles the human one is still largely unknown. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig and the Max Planck Institute for Psycholinguistics in Nijmegen have now discovered that chimpanzees are more likely to copy an action performed by a large number of individuals than an action that was performed more frequently. Two-year old children consider both the number of individuals and the frequency of the action demonstrated. For orangutans, however, none of the factors play a role.