Founder effect in tupian languages

Abstract

Since Mayr (1954, 1963), it has been observed that territorial expansions may cause founder effects , reducing the genetic variability of the founder population. A similar effect has been reported within linguistic typology, as the phonemic inventory size of a language is reduced due to territorial dispersal of its speakers. Atkinson (2011) analyzes global present-day phoneme inventory size as a reflection of a serial found effect caused by human exodus out of Africa during the Paleolithic period: the further a language is from eastern-southern Africa, the smaller its phonemic inventory is. Recent studies have shown that this founder effect may interact with other factors such as population size and language contact and isolation. In the present study, we analyze the phonemic effects of the dispersal of Tupi-Guarani people. Taking the basins of Madeira and Guaporé rivers to be the birthplace of Proto-Tupi (RODRIGUES, 1964), we investigated whether physical distance from Madeira- Guaporé is related with phonemic clines within Tupi-Guarani languages located in the southwest region of South America. We also analyzed whether population size is a significant factor, but it did not interact with phonemic inventory size. A variance test, however, showed that languages in the Madeira-Guaporé region present, among themselves, more vocalic variation than southwest Tupi-Guarani languages. This result is compatible with a founder effect. Contrasting with Tupi languages spoken in Madeira-Guaporé, southwest Tupi-Guarani languages are quite harmonious with respect to vowels, presenting two symmetrical series of nasal and oral vowels. This result and the general discursion we present here converse with studies on reconstruction of Proto Tupian languages, and with investigations on the mental representation of vowels and consonants (NESPOR et al., 2003). If vowels are markers of structural relations, we predict that there is more structural cohesion (less parametric variation) among Southwest Tupi-Guarani than among Tupi languages at Madeira-Guaporé.