Introduction: archaeogenetics and phylogeography
Archaeogenetics was described by Renfrew as ‘the study of the human past using the techniques of molecular genetics' - involving the collaboration of geneticists with archaeologists, anthropologists, historical linguists, and climatologists.
He traced its origins to the pioneering work of Cavalli-Sforza in the 1960s, using classical genetic markers (such as blood groups, etc.). Ammerman and Cavalli-Sforza developed a suite of new approaches, in particular the use of principal component maps, to evaluate the distribution of genetic variation in space. Their results on Europe, in particular, were taken to imply large-scale demic diffusion of farming communities from the Near East with the advent of the Neolithic. The discipline was then renewed in the 1980s by Wilson's work on mitochondrial DNA (mtDNA), as DNA sequencing started to become routine, making it possible for the first time to build genealogical trees of lineages within a species.1The emphasis on developing novel methodologies was extended and deepened as the subject expanded. This is the key to the ongoing controversies in the field, since the analytical approaches are rarely accepted by all practitioners, who hail from widely varied backgrounds. As archaeogenetics went molecular, Wilson and his colleagues developed the phylogeographic [12] approach to molecular marker systems, already emerging in zoology and molecular ecology, applying it to mtDNA variation within the human population. Phylogeography added a genealogical - and therefore also a chronological - dimension to the spatial distribution of genetic markers. Archaeogenetics was again developing its own approaches to data handling, hybridizing techniques borrowed from a variety of disparate disciplines. Voices were raised against this approach, advocating that the new subject should rather be using standard population-genetics methods, which had been developed with quite different questions in mind. This dispute within archaeogenetics has persisted, through various transmutations, to the present day, becoming enmeshed in a rather one-dimensional debate about the scale of Neolithic Near Eastern immigration into Europe which still dominates the subject.[13]