Lexical tone and the Comparative Method: Distinguishing innovation, retention, and chance resemblance

The Comparative Method (CM) is a primary tool for determining relationships between languages and reconstructing proto-languages (Weiss 2015). Increases in available data provide an opportunity to extend the CM to lexical tone. The Tai languages make an ideal testbed, using the Gedney (1972) tone box to map correspondences between historical onsets and modern tones. A corpus of 362 doculects is tested for phylogenetic signal with the D statistic (Fritz & Purvis 2010), and traits are categorized as shared retentions vs. innovations, in order to build a better trait set for phylogenetic comparison and reconstruction. Tai languages thus serve as a model for how we can apply the CM to lexical tone generally.