Evolution of symbolic communication : an embodied perspective
Brown, Jessica Erin
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This thesis investigates the emergence in human evolution of communication through symbols, or conventional, arbitrary signs. Previous work has argued that symbolic speech was preceded by communication through nonarbitrary signs, but how vocal symbolic communication arose out of this has not been extensively studied. Thus far, past research has emphasized the advantages of vocal symbols and pointed to communicative and evolutionary pressures that would have spurred their development. Based on semiotic principles, I examine emergence in terms of two factors underlying symbols: interpretation and conventionalization. I address the question with a consideration of embodied human experience – that is, accounting for the particular features that characterize human communication. This involves simultaneous expression through vocal and gestural modalities, each of which has distinct semiotic properties and serves distinct functions in language today. I examine research on emerging sign systems together with research on properties of human communication to address the question of symbol emergence in terms of the specific context of human evolution. I argue that, instead of in response to pressures for improved communication, symbolic vocalizations could have emerged through blind cultural processes out of the conditions of multimodal nonarbitrary communication in place prior to modern language. Vocalizations would have been interpreted as arbitrary by virtue of their semiotic profile relative to that of gesture, and arbitrary vocalizations could have become conventionalized via the communicative support of nonarbitrary gestures. This scenario avoids appealing to improbable evolutionary and psychological processes and provides a comprehensive and evolutionarily sound explanation for symbol emergence. I present experiments that test hypotheses stemming from this claim. I show that novel arbitrary vocal forms are interpreted and adopted as symbols even when these are uninformative and gesture is the primary mode of communication. I also present computational models that simulate multi-channel, heterosemiotic communication like that of arbitrary speech and nonarbitrary gesture. These demonstrate that information like that provided by gesture can enable the conventionalization of symbols across a population. The results from experiments and simulations together support the claim that symbolic communication could arise naturally from multimodal nonarbitrary communication, offering an explanation for symbol emergence more consistent with evolutionary principles than existing proposals.