Usage frequency and lexical class determine the evolution of kinship terms in Indo-European

Tools from evolutionary biology have been used with great success in historical linguistics, modelling how words are replaced over time in related languages. One limitation to biological approaches, however, is that many macro-evolutionary methods assume trait independence, whereas classes of words form systems. Kinship words provide an example: if you have separate words for your mother’s sister and your father’s sister, you will be more likely to have separate words for your mother’s brother and your father’s brother as well. This has consequences for how such words are used and how they change over time. This, in turn, underlines the importance of language-specific aspects in adapting evolutionary models to explain linguistic patterns.