Language Evolution and Computation Bibliography

The evolution of languages shares certain characteristics with that of genes, such as the predominantly vertical line of transmission and the retention of traces of past events such as contact. Thus, studies of language phylogenies and their correlations with genetic phylogenies can enrich our understanding of human prehistory, while insights gained from genetic studies of past population contact can help shed light on the processes underlying language contact and change. As demonstrated by recent research, these evolutionary processes are more complex than simple models of gene-language coevolution predict, with linguistic boundaries only occasionally functioning as barriers to gene flow. More frequently, admixture takes place irrespective of linguistic differences, but with a detectable impact of contact-induced changes in the languages concerned.

The expansion of Bantu languages represents one of the most momentous events in the history of Africa. While it is well accepted that Bantu languages spread from their homeland (Cameroon/Nigeria) approximately 5000 years ago (ya), there is no consensus about the timing and geographical routes underlying this expansion. Two main models of Bantu expansion have been suggested: The ‘early-split’ model claims that the most recent ancestor of Eastern languages expanded north of the rainforest towards the Great Lakes region approximately 4000 ya, while the ‘late-split’ model proposes that Eastern languages diversified from Western languages south of the rainforest approximately 2000 ya. Furthermore, it is unclear whether the language dispersal was coupled with the movement of people, raising the question of language shift versus demic diffusion. We use a novel approach taking into account both the spatial and temporal predictions of the two models and formally test these predictions with linguistic and genetic data. Our results show evidence for a demic diffusion in the genetic data, which is confirmed by the correlations between genetic and linguistic distances. While there is little support for the early-split model, the late-split model shows a relatively good fit to the data. Our analyses demonstrate that subsequent contact among languages/populations strongly affected the signal of the initial migration via isolation by distance.

The combination of in-depth molecular anthropological analyses and linguistic investigations exhibits some of the factors involved in the prehistoric language contact. The two parts of the human genome that are studied most widely in molecular anthropology, due to their very specific mode of inheritance, include mitochondrial DNA (mtDNA) and the Y-chromosome. MtDNA is a small circular molecule that exists in large copy numbers in special little organelles in the cell called mitochondria. Its special advantage in molecular anthropological studies lies in the fact that it is inherited solely in the maternal line. The Y-chromosome, on the other hand, is one of two sex chromosomes found in the human genome, with the X-chromosome being its counterpart. Molecular anthropological analyses can provide indications of prehistoric admixture events, sex-biased migration patterns, decreases or increases of population size, and settlement practices. These results allow insights into prehistoric sociocultural practices that may have had an effect on language change in contact situations. The detection of prehistoric language shift is significantly important in the study of language contact. The language shift can result in a mismatch between the genetic and linguistic affiliation of a group, which can be detected with genetic methods. The linguistic investigations of languages, which can be shown genetically to have been the target of a language shift, can provide evidence for what linguistic changes, if any, such a shift produces.