Sally Thomason gave an invited talk, "Historical Linguistics: 1924-2014", as part of the Ninetieth Anniversary of the LSA: A Commemorative Symposium, at the annual meeting of the LSA in Minneapolis on January 4.
By 1924, research in historical linguistics was solidly grounded in
the Comparative Method, which was fully developed by the beginning of the 20th century. The vast majority of historical linguists in the early decades of the 20th century concentrated on elucidating the histories of Indo-European languages. The position and significance of two branches of the family -- Anatolian and Tocharian -- were not fully understood at the time the LSA was founded, but the main outlines of the family and the main innovations in its other eight branches were already well understood by then. Genetic classification of a number of other language families was also well under way. In the past 90 years several major scholarly initiatives have significantly altered the field. First, historical research on languages and language families all over the world has expanded dramatically. In addition, the scope of historical linguistic investigation has expanded beyond the traditional foci (lexicon, phonology, morphology) to include phonetic research on sound change and sophisticated studies of syntactic and semantic change. These advances in the breadth and depth of research in the area, together with all the new data from newly explored language families, have led to exciting new theoretical proposals and a greatly increased database on which theories can be tested. Second, the study of contact-induced language change has become much more prominent than it was in 1924; this in turn has led to major advances in distinguishing between internally-motivated and externally-motivated linguistic changes, and therefore to more satisfactory explanations of changes. Third and most recently, historical linguists, biologists, and computer scientists have been adapting quantitative methods drawn from biology in efforts to solve historical linguistic puzzles.