The adaptive significance of human language: Function, form and social evolution

Thesis

Language is arguably one of the most salient features that distinguish humans from other animal species. However, despite the existence of a large body of relevant theoretical and empirical research, there is currently no consensus as to why language emerged exclusively in the human species or how it evolved its unique communicative structure.

In this thesis, I therefore take a multi-pronged approach to analysing and testing several different hypotheses for the biological function and evolution of language. In Chapter I, I review the evidence and theoretical arguments for each of these proposals and provide, in place, a synthetic perspective which integrates or eliminates each of these ostensibly competing hypotheses for the biological function of language. In Chapter II, I employ the first experimental test of the interdependence hypothesis: the unique proposal offered to explain the emergence and potential coevolution of language and cooperation in the human species. In pursuit of this experiment, I employed a cooperative social foraging task using small and large groups to determine what factors enable individuals to make sense of information from others and converge upon a group consensus. In Chapter III, I take an experimental approach to determine whether aspects of human language can be characterised in terms of honest signalling theory. In this respect, I test several different proposals predicted by the sexual selection and deception hypotheses for human language function.

In Chapter IV, I divert attention away from biological function to focus more closely on language structure. More specifically, I take an experimental approach to the problem of how and indeed whether recursive syntax evolved to be a consistent feature of human language. In pursuit of this experiment, I utilized the Imposing Memory Task (IMT) and a recursive syntax measure, to determine relative performance on each of these cognitive tasks, thereby testing whether recursive syntax may have evolved in tandem with higher-order intentionality (also known as embedded mindreading).

Finally, in Chapter V, I discuss the results and implications of these experiments, and possible suggestions for future studies.

Authors: Oesch, NT

• Alternative title: Adaptive significance of human language
• DOI: 10.5287/ora-zga2egpjw
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Language evolution; Honest signalling theory; Evolutionary psychology; Intentionality; Mindreading; Mentalising; Evolution of language
• Subjects: Language evolution; Historical linguistics; Evolutionary psychology; Evolutionary linguistics; Evolution of language; Evolution of intelligence