From transitive to causative in Japanese: Morphologization through exaptation

Modern Japanese has a morphological causative, formed by suffixes on the verb, and lexical causatives. The morphological causative has been in use since Late Old Japanese. However, the etymology of this morphological causative and the status of related causative formations in Old Japanese remain unclear. This paper supports the view that lexical causative formations in Old Japanese are the direct predecessors of the morphological causative. In their morphological, syntactic, and semantic features they form a chain of morphologization with the productive causative that emerged from them. Similar diachronic developments have also been observed in Sanskrit and North American languages. Thus, the formation of a morphological causative from a lexical pattern, a path of development that has received little attention, seems to constitute a crosslinguistically valid source for the evolution of productive causatives. It is proposed that the type of change observed here is an exaptation of fossilized morphological material, which, in several important aspects, runs counter to the directionality of change posited in mainstream grammaticalization theory.