One standout feature of human language is our ability to reference external objects and events with socially learned symbols, or words. Exploring the phylogenetic origins of this capacity is therefore key to a comprehensive understanding of the evolution of language. While non-human primates can produce vocalizations that refer to external objects in the… (More)
We welcome the correspondence from Fischer and colleagues regarding our recent paper on vocal learning in chimpanzee food grunts . Fischer et al. make two challenges to our paper's conclusions, which we address here.