Language evolution and change: the impact of modern evolutionary thinking [Invited talk]

The origins and evolution of language and speech, and the processes governing language change represent major areas of interdisciplinary research impacting not only on language sciences but also on the fundamental question of what it means to be human. However, their scientific investigation is notoriously difficult due to a lack of data and, partly as a consequence, a tendency for debates to be driven by a priori strong theoretical positions. Probably the dominant proposal within linguistics was that language emerged suddenly and recently, coincident with a speciation event that resulted in our own species, Homo sapiens . Various proposals included a single (or a few) genetic mutation(s) resulting in the sudden appearance of core language properties (such as recursion) through unspecified mechanisms, sometimes with clear anti-evolutionary connotations. However, recent advances in our understanding of language and speech and their neural and genetic underpinnings strongly advocate against such saltationist scenarios, and together with new data from archaeology, palaeoanthropolgy and ancient DNA, favour the gradual emergence of language and speech on a much longer timescale going back at least to our last common ancestor with the Neandertals. The complexity of these biological foundations of language require new theories of language acquisition and use that highlight the constant interaction between culture and genetics. Another important insight is represented by the role played by language as a cultural phenomenon in a process of gene-culture co-evolution whereby language constructs a specific niche which, in turn, changes the landscape of selective pressures acting on our genome. In this sense, language and speech (and the culture they support) are very powerful cases of phenotypic plasticity with trans-generational consequences. Relatedly, the idea that language is a true evolutionary system in itself becomes more and more mainstream, and methods adapted from evolutionary biology (such as Bayesian phylogenetics and phylo-geography) are successfully applied to recalcitrant problems in historical linguistics. Thus, recent advances such as evo-devo, the appreciation of phenotypic plasticity and developmental robustness and the complexity of the evolutionary processes afforded by the structure of our genomes, both inform and can be informed by debates in language evolution. However, we must be careful in how we transfer such concepts, methods and findings across disciplines, as there is the real danger that superficial and metaphorical appeals to evo-devo are used to justify old and fundamentally non-evolutionary proposals, confusing the literature and creating false debate