This book addresses the complex question of how and why languages have spread across the globe: why do we find large language families distributed over a wide area in some regions, while elsewhere we find clusters of very small families or language isolates? What roles have agriculture, geography, climate, ethnic identity, and language ideologies played in language spread? In this volume, international experts in the field provide new answers to these and related questions, drawing on the increasingly large databases available and on novel analytical research techniques. The first part of...