Prof. John Peterson
The 'Great Indo-Aryan Divide' and what it can tell us about the prehistory of South Asia
In my talk I present evidence from recent studies (e.g. Peterson, 2017) showing that modern Indo-Aryan languages, regardless of their internal genealogical relationships, show a relatively clear split between eastern and western languages with respect to structural properties such as case marking, gender systems, number systems, etc. While the eastern languages share many similarities with Munda languages and northern/eastern Dravidian languages, the western Indo-Aryan languages tend to cluster structurally with southern and western Dravidian languages. This points to a considerable amount of language contact in earlier times between these different language families and eastern and western Indo-Aryan, respectively.
A closer look at these two groups of Indo-Aryan reveals that eastern Indo-Aryan languages in general show clear signs of historical simplification above all with respect to their nominal morphology, with the (almost total) loss of the inherited case system, fewer grammaticalized cases, a simplification of the gender systems, and a greatly reduced number of irregular verbs. Such simplifications are typical of language-contact situations in which large numbers of speakers of these languages would at one time have been adult learners, e.g. using (Old or Middle) Indo-Aryan as a lingua franca with other ethnicities while retaining their home languages in intra-group communication. By contrast, in western Indo-Aryan languages, while changes did occur, they did not result in such drastic simplifications, and some languages such as Konkani even show signs of increased complexity. This last situation is typical of long-term, stable bilingualism from childhood onward (e.g. Trudgill, 2011).
Taken together, these facts suggest that ca. 2,000-2,500 years ago eastern and western Indo-Aryan languages were spoken in very different sociolinguistic environments, with a high degree of ethnic and linguistic diversity in eastern India and a comparatively low level of diversity in the west, differences which will surely also have played a role in the further cultural development of these two regions.