Proto-Bantu reflexes in Dhaisu

This paper is a study of Proto-Bantu reflexes in Dhaisu, a highly endangered lan-
guage also known as Dhaiso, Segeju, Daisu and Kidhaisu (dhs, E56). Dhaisu is spo-
ken in the East Usambara Mountains in northeastern Tanzania, but its closest rel-
ative is Kamba (E55). Seven vowels are reported in this study as has been in other
studies /i, ɪ, ɛ, a, ɔ, ʊ, u/. However, no contrast can be established between ɪ and
ɛ, or between u and ʊ. The data show that Dhaisu vowel system is changing to a
5-vowel system *i̧, *i, *e, *a, *o, *u, *u̧ > /i, ɛ, a, ɔ, u/. The most remarkable feature
of this change is that unlike other Bantu languages, which merge the mid-high to
high vowels, Dhaisu is merging the mid-high vowels to mid-low. The innovation
is demonstrated in (a) numerous lexical items in which Proto-Bantu *i has become
ɛ, and PB *u has become ɔ; (b) several nominal prefixes that are constructed in PB
having mid-high vowels now have mid-low vowels, and (c) the applicative suffix
whose PB form was *id is now -ɛr in Dhaisu. The fact that the change does not seem
to have affected all nominal prefixes with mid-high vowels, and has affected not
all verbal derivation with mid-high vowel suggests an ongoing transition. Reflexes
of consonants are presented to show that they are not a result of spirantization.