Using plentiful, engaging, and challenging examples, Ruhlen teaches how to classify languages and decipher their roots. Walks readers through the fascinating steps of tracing the origins and development of all the 5,000 languages known to have been spoken in human history. Covers the latest discoveries in genetics and evolutionary biology as well as the raging debates in the linguistic world over the theory of the "mother tongue." Introduces a major emerging synthesis in the scientific world regarding the three fields of linguistics, evolutionary biology, and archeology, explaining how this synthesis is changing our understanding of human civilization's development.