Paradigmatic restructuring and the diachrony of stem alternations in Chichimec

Stem alternations contribute a unique type of morphological complexity to inflectional systems (Baerman et al. 2015), but despite the fact that they can show remarkable stability over time (Maiden 2018), the manner in which they are maintained and the types of changes they undergo are still poorly understood, in particular when it comes to understudied languages for which diachronic data are usually nonexistent. The verbal inflection of Chichimec (Oto-Pamean, Mexico) is characterized by intricate distributions of stem alternations, and it affords us a unique opportunity to study them from a diachronic perspective, because, unlike most other minority languages, we have a precise and detailed description of its verbal inflection system from almost a century ago (de Angulo 1933) from which we are able to reconstruct the paradigms of 170 verbs. In this article, we compare the verbal system as it was registered by de Angulo in 1930 to our own primary data recorded during two recent field trips. We show evidence that certain elements of the intricate patterns of stem alternations have been reanalyzed and redistributed by the speakers. We argue that the changes make sense only from a morphological perspective in which stem alternations are seen as involving fixed configurations of cells, or 'morphomes' (Aronoff 1994). We also show that speakers have not manipulated these configurations in isolation but in clusters, resulting in a substantial restructuring of verbal inflection at the paradigmatic level. We conclude that the changes have not resulted in a simpler system, but rather one that, while almost the same in terms of morphological complexity, has become more consistent