If we compare the paradigm of the 1st p. pr. in Dargwa dialects, it becomes probable that PD *nu is a secondary development < *du (or, possibly, *du-n, cf. PL *zon): cf. Ak. nom. nu, erg. nuni, dat. nab vs. Chir. nom. du, erg. di-c:e, dat. damī. Still, PD *nu- in the 1st p. plural *nu-š:a stays unexplained, as well as Lak. na (also < *da-n or *t:a-n, cf. the obl. stem t:u- ?).

    An etymological possibility would be to consider the morpheme *nɨ̆ as originally a collective plural pronoun: cf. its use in PD *nu-s:a 'we' (exclusive), *nu-x:a 'we' (inclusive), *nu-š:a 'you (plur.)', quite parallel to Av. ni-ž, ni-ƛ: and nu-ž. Its usage in the 1st person plural could have influenced the 1st person singular in Lak. and Darg., and this influence was strengthened by a chance of secondary nasalisation (e. g. PD *nu < *du-(n)).