Erratic velars in West-Coastal Bantu

In this article, we present the first quantitative study of what we call multiple unconditioned reflexes (MUR) in Bantu, more specifically of Proto-Bantu velar stops *k and *g in the West-Coastal Bantu (WCB) branch of the Bantu language family. MUR, also known as “doubles reflexes” in Bantu studies, represent a situation where one and the same proto-sound has two or more reflexes in a given language which cannot be accounted for by phonological conditioning and/or lexical borrowing. This diachronic irregularity has been explained in Bantu historical linguistics, and Niger-Congo studies more broadly, by reconstructing either an additional series of consonants (phonemic merger) or a latent conditioning that went lost (phonemic split). We show that MUR should not be explained, but rather taken as an indicator of the same pervasive irregularity of sound change reported in other parts of the world that are highly multilingual and lack a neat overlap between distinct languages and communities. Along with widespread multilingualism, we assess lexical diffusion, substrate influence, and spread-over-spread events in Bantu language history as complementary explanations for the rise of MUR in WCB.