International Journal of American Linguistics
The University of Chicago Press
The Central Numic (Uto-Aztecan) dual number marking system on nouns and pronouns is of interest because even though most of the component morphemes involved in the system are reconstructible to Proto-Numic, the system itself is not. Indeed, while the reconstructible Proto-Numic system is rudimentary, the Central Numic system is robust and has expanded to the point that there are few environments where dual is not marked on equal footing with singular and plural. The Central Numic system is of further interest because it involves cycles of grammaticalization and not just a single diachronic event. This contrasts with the other two branches of Numic, Western and Southern, where the very rudimentary Proto-Numic dual number has been maintained and only minimally expanded. The tarpaper shack of Proto-Numic dual marking is now the steel-and-glass high-rise of Central Numic dual marking.
McLaughlin, John, "Expanding to the Edges: Central Numic Dual Number" (2018). English Faculty Publications. Paper 831.