Demography and the Cultural Evolution of Pictorial Styles

Image-making is a nearly-universal human behaviour. Cultures around the world have made images to convey information about living kinds, objects and ideas for at least 75,000 years. However, from a stylistic point of view, the visual strategies and conventions to represent things in pictures can vary greatly over time and space; in particular, pictorial styles can differ in figurativeness, varying from inter-subjectively recognisable representations of things to stylised and abstract forms. Are there any patterns to this variability, and what might its ecological causes be? In recent Cultural Evolution research, factors such as demography and the structure of interaction between groups of individuals have been shown to affect the evolution of languages and technology. Capitalising on these studies, I investigate the style evolution in relation with the socio-demographic variable of population contact, and in particular the influence of inter-group contact on the figurativeness of pictorial representations. For this purpose, I firstly conducted an experimental study, simulating isolated and contact social groups with laboratory micro-societies performing a drawing task; secondly, I quantitatively analysed a real-world dataset of Aboriginal Australian rock art from contact and isolated communities; then I qualitatively explored the evolution of a contemporary pictorial communication item: emoji. Results show that pictorial representations from isolated groups tend to become abstract and opaque to outsiders, whereas in contact groups they retain figurativeness and external understandability. This supports the idea that intergroup contact is an important factor in the cultural evolution of pictorial styles, because the need to communicate with outsiders and be accessible to the widest possible audience encourages figurativeness. I discuss the implications of these findings for the archaeology and anthropology of art, and the parallels with language evolution. Finally, addressing the need for research outreach in Cultural Evolution, I designed the blueprint of an exhibition aimed at disseminating my research findings while offering lay audiences an engaging and transformative experience

Evolution of symbolic communication : an embodied perspective

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

The role of interactive and cognitive biases in language use and language change

The richness and diversity of human languages is remarkable. Researchers have tried to understand how languages evolved to be how they are now, identifying how processes in language acquisition, transmission, interaction, and use shape their structure. This research comes from different disciplines and methodological approaches, such as typological research, cognitive science, pragmatics, or developmental psychology. This thesis attempts to integrate the learnings from these disparate fields using novel methodological approaches to understand the process and forces in language evolution. This first part of this dissertation, Chapters 2 and 3, explore the effect of interaction in language learning and evolution. We expand on the existing artificial language learning paradigms to allow a real-time observation and monitoring of language learning process through interaction. This novel paradigm allows as to observe how asking participants to guess the meaning of a word before producing it boosts the speed of language acquisition. We also discuss and propose different ways in which these paradigms can be used to directly observe the way in which sociolinguistic, pragmatic, and communicative processes affect language structure while it is being acquired through interaction. Aside from interactive biases, individual cognitive biases also have been shown to affect language evolution. The second part of the dissertation, Chapters 4, 5, and 6, address how domain-general biases in processing can affect language change. We find evidence that illusion of causality and category accentuation biases shape language acquisition, leading to language change and interacting with other communicative and cognitive pressures for language evolution. In summary, this dissertation bridges the gaps between the different disciplines working on understanding language evolution. It offers methodological innovations for the study of language learning through interaction and it shows how domain-general biases can explain some of the variability and observations in language evolution and interact with other better-studied pressures