The causative/applicative syncretism in Mbuun (Bantu B87, DRC): Semantic split or phonemic merger?

Abstract

In Mbuun (B87), a Bantu language spoken in the Bandundu Province of the Democratic Republic of the Congo, the valency-increasing functions of the causative and the applicative have, to a certain extent, the same formal expression. They are encoded morphologically by a derivational suffix which has an uncharacteristic morphophonological realization. It triggers the gemination of the root-final consonant. In this paper, we examine whether this causative/applicative isomorphism is the result of a semantic split or rather the outcome of a phonemic merger. In the first case, the semantic extension must have happened from applicative to causative rather than the cross-linguistically more common evolution from causative to applicative, since the consonant gemination associated with these forms has its origin in the Proto-Bantu applicative suffix *-id-. In the case of a phonemic merger, however, this applicative suffix would have become homophonous with an originally distinct suffix having a causative effect as the result of convergent morphophonological change. This morpheme cannot be the Proto-Bantu causative suffix *-ici-, which still has a residual causative use in Mbuun.