Language Evolution and Computation Bibliography

This paper presents the results of the application of a bit-string model of languages (Schulze and Stauffer 2005) to problems of taxonomic patterns. The questions addressed include the following: (1) Which parameters are minimally ne eded for the development of a taxonomic dynamics leading to the type of distribution of language family sizes currently attested (as measured in the i number of languages per family), which appears to be a power-law? (2) How may such a model be coupled with one of the dynamics of speaker populations leading to the type of language size seen today, which appears to follow a log-normal distribution?

Researchers interested in the history of the Indo-European family of languages have used a variety of methods to estimate the phylogeny of the family, and have obtained widely differing results. In this paper we explore the reconstructions of the Indo- European phylogeny obtained by using the major phylogeny estimation procedures on an existing database of 336 characters (including lexical, phonological, and morpho- logical characters) for 24 Indo-European languages. Our study finds that the different methods agree in part, but that there are also several striking differences. We dis- cuss the reasons for these differences, and make proposals with respect to phylogenetic reconstruction in historical linguistics.

It has been observed that borrowing within a group of genetically related languages often causes the lexical similarities among them to be skewed. Consequently, it has been proposed that borrowing can sometimes be inferred from such skewing. However, heterogeneity in the rate of lexical replacement, as well as borrowing from other languages, can also give rise to skewed lexical similarities. It is important, therefore, to determine to what degree skewing is a statistically significant indicator of borrowing. Here, we describe a statistical hypothesis test for detecting language contact based on skewing of linguistic characters of arbitrary type. Significant probabilities of correct detection of contact are maintained for various contact scenarios, with low false alarm probability. Our experiments show that the test is fairly robust to substantial heterogeneity in the retention rate, both across characters and across lineages, suggesting that the method can provide an objective criterion against which claims of significant skewing due to contact can be tested, pointing the way for more detailed analysis.

Gray & Atkinson's (2003) application of quantitative phylogenetic methods to Dyen, Kruskal & Black's (1992) Indo-European database produced controversial divergence time estimates. Here we test the robustness of these results using an alternative data set of ancient Indo-European languages. We employ two very different stochastic models of lexical evolution - Gray & Atkinson's (2003) finite-sites model and a stochastic-Dollo model of word evolution introduced by Nicholls & Gray (in press). Results of this analysis support the findings of Gray & Atkinson (2003). We also tested the ability of both methods to reconstruct phylogeny and divergence times accurately from synthetic data. The methods performed well under a range of scenarios, including widespread and localized borrowing.

This paper reports the results of an attempt to recover the first-order subgrouping of the Indo-European family using a new computational method devised by the authors and based on a 'perfect phylogeny' algorithm. The methodology is also briefly described, and points of theory and methodology are addressed in connection with the experiment whose results are here reported.