From transitive to intransitive and voiceless to voiced in Proto-Sino-Tibetan

This paper offers new evidence from Stau, Geshiza, and Khroskyabs toaddress the question of directionality in valency-changing derivations inSino-Tibetan. Examining Stau, Geshiza, and Khroskyabs causative andanticausative verb stem pairs adds to the evidence that in Proto-Sino-Tibetan, a number of intransitive stems are derived from transitive stems, insome cases as the result of *N‑ prefixation, and in other cases from voicingalternation independent of *N‑ prefixation. In addition, the proto-sigmaticprefix (*s-) does not cause devoicing in Stau, Geshiza, and Khroskyabs, butrather often undergoes voicing assimilation, and has more than just acausativization function. Furthermore, by looking at Gyalrong, Minyag,Tangut, Middle Chinese, and Old Chinese we emphasize that there is nosynchronic evidence to support devoicing induced by *s‑, nor is therehistorical evidence to support the claim that *s‑ caused devoicing in Proto-Gyalrongic, or even at genetically deeper stages