Perfective and imperfective from the same source

Extensive typological research on spatiotemporal development has shown that directionals tend to start as ‘bounders’, and eventually grammaticalize into perfective or simple-past markers. Meanwhile, recent crosslinguistic studies of tense and aspect have demonstrated that the opposition between perfective and imperfective is the most general contrast expressed via verbal morphology. This paper, however, presents a clear counterexample to the above commonly accepted generalizations. Specifically, rGyalrong languages show a perfective-imperfective distinction, but the past imperfective marker and one of the perfectives developed from the same source — the directional ‘down’. This study thus documents a previously undescribed development, through which a single directional has grammaticalized into two opposing aspectual categories. The unexpected spatio-temporal development presents a challenge to the approach of grammaticalization studies that focuses on ‘major’ developmental pathways.