Homoplasy in diachronic grammar

The application of evolutionary thinking to language change has a long tradition, and especially in functional approaches it is currently widely accepted that certain mechanisms can be fruitfully used to describe both biological and linguistic processes. In this article, the evolutionary concept of homoplasy, the recurrence of similar traits in unrelated lineages, is applied to language change. Extending the earlier application of the concept by Lass (1997), homoplasy is here argued to operate not only on the phonological level, but on the morphosyntactic level as well, and not only between languages but also within languages, at the level of constructions. The idea is that phenotypic resemblance in constructions may hide etymological differences. In other words: what looks the same from a synchronic perspective may derive from multiple source constructions historically. On the basis of four case studies in Dutch diachronic morphosyntax, it is shown that homoplasy can offer an insightful account of some long-standing puzzles.