Human language is unique among the communication systems of the natural world, providing our species with an incredibly flexible and powerful open-ended system of communication. The expressive potential of language undoubtedly contributes to the human capacity to build on the achievements of our peers and ancestors, producing the capacity for cumulative culture that defines our species, and which has enabled us to spread across the planet and beyond. The communication systems of non-human animals are far more limited, both in their expressive potential and in the structural devices they deploy to facilitate communication; while there are important homologies and analogies between the human capacity for complex language and the communication systems of non-humans, human language seems to be qualitatively different. How did this state of affairs come to pass?
Humans learn the language of our speech community based on observing their utterances and the way in which they are used, inferring the underlying system of rules which govern how linguistic forms are constructed, the meanings those complex utterances convey, and how form and meaning are related. Consequently, language undergoes cultural evolution: it changes over time as a result of pressures applied during learning and use. On this grant we are exploring how these processes of linguistic evolution might drive the evolution of complexity in humans languages – under what conditions is complexity favoured by the cycle of learning and use by which languages persist?
We are adopting two main approaches to this problem. Firstly, the right kind of complexity in the right place in a linguistic system might facilitate language learning: if so, complexity would be predicted to emerge as a result of the transmission of language from learner to learner over long timescales. Secondly, complex social environments might drive the evolution of expressive power and complexity in language – communication in between cognitively sophisticated individuals who reason about their interlocutors’ linguistic knowledge, world knowledge, and social status, and adjust their linguistic behaviour accordingly, might provide a rich environment in which linguistic complexity can accrue.
These ideas are of far-reaching importance for our understanding of the evolution of language and linguistic complexity, but have not yet been subjected to a concerted empirical examination: our aim in this project is to provide such an examination.
