Language enables humans to communicate about an infinite range of everyday events by combining a relatively limited set of sounds. In contrast, the ability of animals to string together calls to communicate about a wide range of events is seen as limited. Researchers from the Max Planck Institutes for Evolutionary Anthropology and for Cognitive and Brain Sciences in Leipzig, Germany, and the CNRS Institute for Cognitive Sciences in Lyon, France, recorded and analysed thousands of vocalisations from wild chimpanzees in Ivory Coast. The researchers observed that when chimpanzees were engaged in a single event (like eat, play, rest, greet), they were likely to emit a single call. However, when engaged in more than one event at a time (like eat and greet, travel and meet) chimpanzees were twice as likely to use vocal sequences than single calls. Also, chimpanzees who engaged in a wider range of events produced more diverse vocal sequences. These new results suggest that chimpanzees possess crucial prerequisites for the evolution of compound communication.