The Trans-caucasus and the Expansion of the Caucasoid-specific Human Mitochondrial Dna

The topology of the network of western Eurasian mitochondrial DNA (mtDNA) lineage clusters in the context of their expansion and spread in this geographic area is analysed. Special attention is devoted to the inner nods of the reconstructed median network tree, ancestral to mtDNA lineage clusters H and V, to the Caucasus and TransCaucasus area populations and to the problem of timing of the expansion of the Caucasoid-specific mtDNA lineage clusters in western Europe versus in the Trans-Caucasus. It appears on several examples that typical for Western Europe mtDNA lineage clusters exhibit significantly earlier expansion in the Trans-Caucasus area. Furthermore, the lineage cluster, radiating from the pre-HV node, is significantly more frequent and divergent in the Trans-Caucasus populations than it is in Europe. Meanwhile, a comparison of the Central Asian and the Trans-Caucasus area populations shows that the former have a significant share of eastern Asian-specific mtDNA lineages, which are almost absent in the latter. Finally, a picture starts to emerge, revealing an ancient Indian— Trans-Caucasian—European continuum of a significant proportion of human maternal lineage clusters, dating back to the period between the Upper and Lower Pleniglacials.