Presented as part of the Centre for Research on Language Change Seminar Series

Human languages contain two levels of systematicity: one meaningful/compositional (e.g. morphosyntax) and one meaningless/combinatorial (e.g. phonology). This 'duality of patterning' is unique to human communication (Hockett, 1959; Martinet, 1960/1984; Ladd 2012). There have been a number of evolutionary explanations for this uniqueness, often relying on mechanisms of natural selection. However, a growing body of work targets an alternative explanation: that the phenomenon is the product of cultural evolution as shaped by various cognitive and social biases. These studies feature both formal modelling (e.g. Kirby, 2002; De Boer, 2000, Tria, 2012) and communication experiments (e.g. Kirby, Cornish, Smith, 2008; Verhoef 2012). My plan is first to provide a survey of the field, and in particular the proposal from Kirby et al (2015) that linguistic structure emerges under twin pressures of compression and communication. Following this, I will look at how we can apply this argument to duality of patterning more generally. I argue that if we take an information-theoretic perspective, both types of systematicity can be seen as functional adaptations to maintain expressivity in the face of noisy processes at different levels of analysis. Finally, I will discuss how this might apply to the emergence of more complex structural processes such as found in natural language syntax.

Matt Spike is a postdoctoral fellow at ANU in the ARC Centre of Excellence for the Dynamics of Language.