Published online by Cambridge University Press: 01 January 2026
This study uses phylogenetic methods adopted from computational biology in order to reconstruct features of Proto-Indo-European morphosyntax. We estimate the probability of the presence of typological features in Proto-Indo-European on the assumption that these features change according to a stochastic process governed by evolutionary transition rates between them. We compare these probabilities to previous reconstructions of Proto-Indo-European morphosyntax, which use either the comparative-historical method or implicational typology. We find that our reconstruction yields strong support for a canonical model (synthetic, nominative-accusative, head-final) of the protolanguage and low support for any alternative model. Observing the evolutionary dynamics of features in our data set, we conclude that morphological features have slower rates of change, whereas syntactic traits change faster. Additionally, more frequent, unmarked traits in grammatical hierarchies have slower change rates when compared to less frequent, marked ones, which indicates that universal patterns of economy and frequency impact language change within the family
Equal author contribution. The work was supported by the Marcus and Amalia Wallenberg Foundation, grants MAW 2012.0095 and MAW 2017.0050, both awarded to Gerd Carling. We thank audiences at the 50th annual meeting of the Societas Linguistica Europaea, the 24th International Conference on Historical Linguistics, and the linguistics seminars at Lund, Zurich, and Göttingen Universities for valuable remarks, along with three anonymous referees, Simon Greenhill, and the Language editors. We also thank Filip Larsson, Niklas Erben Johansson, Erich Round, Sandra Cronhamn, and Arthur Holmer for helpful comments on data, study design, and results, and Johan Frid for preparing trial versions of some of the graphs. Special thanks are due to Gerhard Jäger for help on various technical matters as well as for providing the proof included in the online supplementary material.