Paradigmatic complexity metrics as signals of phylogenetic relatedness

Abstract Morphological complexity metrics like entropy, and notions like the Paradigm Cell-Filling Problem, have recently (re)gained popularity for the synchronic analysis of inflectional systems. The potential of these quantitative approaches for diachronic research, however, remains largely untapped. This paper constitutes a first exploration of whether and, if so, how these methods can be used profitably in this domain. We first use Romance, for which we have rich historical knowledge, to establish the diagnostic value of complexity metrics for phylogenetic relatedness under a best-case scenario. We then apply these methods to Pamean (Otomanguean, Mexico) to show that the same metrics help diagnose the phylogenetic relatedness of tenses and inflection classes even when, as is the case in this family, most of the morphological material has been replaced or altered beyond recognition. Results suggest that complexity metrics can successfully diagnose phylogenetic relatedness over extended periods of time and fruitfully complement traditional qualitative approaches.