Constraining disharmony in Nilotic: What does an optimal system look like?

Abstract

Vowel harmony systems of the so-called cross-height type are found throughout the Nilo-Saharan and Niger-Congo language families, with an extension into neighbouring Afroasiatic languages. Whereas it is common practice to focus on the esthetic aspect of harmony, many systems in actual fact leak, with disharmony within words being an important inherent property of such systems as well. The present study focuses on disharmony in the Nilotic branch within Nilo-Saharan. Here disharmony can be shown to result from vowel shifts disrupting or complicating the system; alternatively, disharmony occurs as a result of the cliticisation and affixation of formerly free morphemes with their own independent vowel features. In tandem with these historical changes, one may observe a tendency to constrain the degree of disharmony. A historical comparison of different Nilotic languages shows, however, that individual languages have developed different constraints on disharmony in the sense of Pulleyblank (1993). The present contribution seeks to investigate some of the mechanisms behind these divergent developments.