Complex diachronies of final nasalization in Austronesian and Dakota

Final nasalization of voiced stops is phonetically unmotivated (i.e. not a consequence of universal articulatory or perceptual tendencies). As such, final nasalization has been deemed an impossible sound change. Nonetheless, Blust (2005; 2016) proposes that final nasalization took place in four Austronesian languages: Kayan-Murik, Berawan dialects, Kalabakan Murut, and Karo Batak. In this paper, we argue final nasalization in these languages is not a single sound change and reduce it to a combination of phonetically grounded changes. We demonstrate that in Austronesian, final nasalization involved four steps: (i) fricativization of voiced stops, (ii) devoicing of the fricatives, (iii) spontaneous nasalization before voiceless fricatives, and (iv) occlusion of the nasalized fricatives to nasal stops. Finally, we extend our account to final nasalization in Dakota (Siouan) and propose a new explanation for the development of the unnatural final voicing in the related Lakota language. Our results shed light on the role of phonetic naturalness in diachrony and synchrony. We maintain that while phonetically unnatural phonological processes may arise via a sequence of sound changes or analogical extension, sound changes are always natural and phonetically grounded.