Bioinformatic methods in calculating language relationships

The ESSLLI course material has been compiled by Anke L ¨ udeling and Ulf Leser. Unless otherwise mentioned, the copyright lies with the individual authors of the material. Anke L ¨ udeling and Ulf Leser declare that they have obtained all necessary permissions for the distribution of this material. ESSLLI 2008 and its organizers take no legal responsibility for the contents of this booklet. In this work we probe phylogenetic algorithms for their ability to reconstruct historic language relationships. We present a formal model for the development of languages incorporating vertical (genealogical) and horizontal (language contact) eects. As a distinctive feature, we also added a geographic model to mimic the eects of constrained population movements. Using our model, we generated a large number of simulated language histories whose results were analyzed by a variety of established phylogenetic algorithms. Therein, we systematically investigated the eects of dierent contact intensities and of geographic as well es genealogic topologies. We found that tree-based algorithms are robust under a variety of dierent settings and are capable of inferring (parts of) the relationships correctly even under high levels of network-like inuences. We also studied the SplitsTree algorithm which should be more appropriate to cope with network-like eects. However, although SplitsTree clearly performs better in some settings, it generally shows a rather erratic behavior.