The origin of the causative prefix in Rgyalrong languages and its implication for proto-Sino-Tibetan reconstruction

In this paper, the first detailed description of the two causative derivations in Japhug Rgyalrong is presented, based on a corpus of spontaneous speech. Two new pathways of grammaticalization are proposed. First, it is shown that the causative derives from a special type of denominal derivation. Second, a previously undocumented development from the causative to the abilitative derivation is described. Lastly, the implications of these grammaticalization hypotheses for the reconstruction of Sino-Tibetan morphology as a whole are evaluated.