Diachrony of experiencer subject marking

Daghestanian languages of the Caucasus show consistent use of the dative and locative cases to mark subject arguments with certain verbs, most notably the experiencers of the verbs ‘see’, ‘hear’, ‘know’, ‘want’, ‘forget’, ‘find’ and some others. Although this pattern is very stable and can probably be reconstructed for Proto-Daghestanian, variation in experiencer marking reveals that diachronic changes happened to non-canonical subjects at a later stage of evolution. The paper looks into two related issues concerning the diachrony of experiencer subjects in Daghestanian languages: the relative diachronic stability of non-canonical case marking and non-canonical agreement, and the loss of non-canonical subjects in Udi and Dargwa.