Don Ringe was educated at the University of Kentucky, Oxford, and Yale and has taught Classical studies and linguistics at the university level since 1983. He is Kahn Endowed Term Professor in Linguistics at the University of Pennsylvania and the author of numerous publications on comparative Indo-European linguistics, historical linguistics, and computational cladistics, including On the Chronology of Sound Changes in Tocharian and From Proto-Indo-European to Proto-Germanic (OUP 2006) the forerunner of the present volume. Ann Taylor is Senior Lecturer in Linguistics at the University of York. Her main research area is variation and change in the history of English with a primary focus on syntax. She works within a framework that applies quantitative methodology first developed within variationist sociolinguistics to the structural analysis of historical data, and combines formal syntactic analysis, statistical methods, and techniques of corpus linguistics.