Conversation is the most proximate causal locus of language evolution and change. It is widely recognised that utterances provide the primary adaptive context for linguistic items (Croft 2000). However, utterances themselves occur in larger conversational sequences which have rich internal structure. This is the ecology in which utterances live and in which linguistic items are replicated. What is the effect of this ecology on language structure? What are the constraints and selective pressures that it imposes?

In this talk I render these questions tractable by focusing on a circumscribed domain of conversational structure: "other-initiated repair", roughly the machinery that people use to with troubles of speaking, hearing and understanding in conversation. A comparative study of this domain reveals that languages converge on similar sets of resources, including the use of interjections, question words, politeness formula, and repetition (Dingemanse, Blythe and Dirksmeyer 2014).

One of these resources is not only similar in function but also in form. In a comparative study of 31 spoken languages, we find that all of them have an interjection like 'huh?' for the function of initiating repair (Dingemanse, Torreira and Enfield 2013). I discuss the proposal that this similarity is due to convergent evolution in an environment that is shared across all languages. I end by discussing the larger implications for the study of language change and language typology.

Croft, William. 2000. Explaining Language Change: An Evolutionary Approach. Harlow: Pearson Education Limited.

Dingemanse, Mark, Joe Blythe, and Tyko Dirksmeyer. 2014. “Formats for other-initiation of repair across languages: An exercise in pragmatic typology.” Studies in Language 38 (1): 5–43. doi:sl.38.1.01din.

Dingemanse, Mark, Francisco Torreira, and N.J. Enfield. 2013. “Is ‘Huh?’ a universal word? Conversational infrastructure and the convergent evolution of linguistic items.” PLOS ONE. doi:10.1371/journal.pone.0078273. http://dx.plos.org/10.1371/journal.pone.0078273.