Human language allows an infinite generation of meaning by combining phonemes into words and words into sentences. This contrasts with the very few meaningful combinations reported in animals, leaving the mystery of human language evolution unresolved. Researchers from the Max Planck Institutes for Evolutionary Anthropology and for Cognitive and Brain Sciences in Leipzig, Germany, and the Cognitive Neuroscience Center Marc Jeannerod (CNRS/Université Claude Bernard Lyon 1) and Neuroscience Research Center (CNRS/Inserm/Université Claude Bernard Lyon 1) in Lyon, France, recorded thousands of vocalisations from wild chimpanzees in Taï National Park, Ivory Coast, and investigated the rules by which meanings are modified when calls are combined into two-call combinations. They identified four mechanisms by which chimpanzees modify meanings in two-call combinations that mirror principles in language. These include compositional structure, idiom-like meaning generation, and ordering effects on meaning, a cornerstone of syntax. These findings challenge the notion that complex combinatorial communication is uniquely human, and bring us a step closer to understanding the origins of our own linguistic capacities.