Abstract
In this chapter we suggest that the origin of language, specifically the protolinguistic stage, was iconic rather than arbitrary, and fundamentally based on shared cross-modal associations. We provide evidence from natural language in the form of sound symbolism, distinguishing conventional sound symbolism from sensory sound symbolism. Sensory sound symbolism, or the presence of iconicity in natural language, is considered alongside psychological experiments in naming, and other investigations of cross-modal associations specifically involving linguistic sound. This evidence supports the idea that we can directly express a variety of sensory experiences through linguistic sound, and thus that language systems have the capacity to be iconic to a large extent. We outline a theory of sensory protolanguage emergence, considering how and why arbitrariness eventually became the dominant relationship between form and meaning. Finally, we consider the possibility of continuity between cross-modal transfer in other primates and more abstract cross-modal associations among humans, suggesting this may have scaffolded the emergence of symbolic communication.