This chapter summarizes the complex relationships between linguistic and speaker biological diversity, on one hand, and the influence of paradigms derived from evolutionary biology, the science of diversity par excellence on understanding language, on the other. An important class of models derived from the principle that associations between genetic and linguistic diversities are related through shared history is represented by attempts at explaining the origins and spread of the major language families, such as Indo-European and Austronesian. The proposal that Indo-European was spread by early farmers expanding from one of the origins of agriculture is only a particular case of a more general language-farming co-dispersal process which purports to explain the distribution of several major language families around the world. The classic approach to the investigation of the genetic foundations of language and speech, predating the advent of modern molecular techniques and the understanding of the complexities of genome.