A recent study in PLoS biology nicely illustrates how modern studies of language evolution and geographic variation are taking advantage of modern population genetic and phylogenetic methods. Although the use of phylogenetic methods in quantititive comparative linguisitics isn't new, this new study is, to my knowledge, the first to use the Bayesian clustering algorithms that are all the rage in population genetics. This study uses these methods to investigate the extraordinarily diverse languages of Sahul (an ancient continent formed from present day Australia, New Guinea and surrounding islands). Previous attempts to infer the history of these languages have been complicated by two problems that will be familiar to any phylogeneticist. The first problem involves identification of homologies - or, in the jargon of a quantitative comparative linguist "phonological and semantic drift [which] make it impossible to identify lexical cognate characters." Another challenge stems from admixture, which may result from the fact that many Sahul languages have been in "long term and intensive contact," . By applying the program Structure to 160 "abstract structural features" quantified for 121 Sahul languages, Reesink et al. are able to recover 10 "ancestral language populations." Many of the clusters recovered by Structure correspond with previously diagnosed language groupings, and the overall patterns of hierarchical clustering suggest plausible historical scenarios. The authors also suggest that, in spite of ample opportunity for interchange, many languages show "negligible amounts of admixture."
Reesink, G., Singer, R., & Dunn, M. (2009). Explaining the Linguistic Diversity of Sahul Using Population Models PLoS Biology, 7 (11) DOI: 10.1371/journal.pbio.1000241
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