Chimpanzees can appear quite human through their actions and expressions, which are often similar to ours. Why, then, have they not become even more human than they are? In this fascinating film a team of scientists from the University of Amsterdam study the social structure of wild chimpanzees in Guinea and conduct some experiments with them. What, for example, will be the chimps' reaction to a stuffed leopard? The answer is provided in one of the most remarkable sequences ever shown in this series.