Since the beginning of the study of both historical linguistics and evolutionary biology, it was recognised in both fields that the principles driving language change and biological evolution have much in common. However, during the following decades the similarities mainly remained a curiosity, without wider repercussions in research. It was only in the second half of the 20th century that attempts were made at creating a theoretical framework encompassing both biological evolution and language change. However, the role of linguistic structures as evolving objects has remained unclear, and the advantages of formulating linguistic problems in terms of evolution have not been obvious. This book seeks to relate concepts in linguistic theory and the study of language change with the requirements of the evolutionary theory. Also, it illustrates and evaluates the practical approaches that can be performed for analysing the history of language families with computational models originating in biological systematics. Consequently, the account serves the interests of researchers of language change and variation, and anyone occupied with the relations between biology and the human sciences.