Phylogenetic star contraction applied to Asian and Papuan mtDNA evolution

In the past decade, mitochondrial DNA (mtDNA) of 826 representative East As ians and Papuans has been typed by high-resolution (14-enzyme) restriction fragment length polymorphism (RFLP) analysis. Compared with mtDNA control r egion sequencing, RFLP typing of the complete human mitochondrial DNA gener ally yields a cleaner phylogeny, the nodes of which can be dated assuming a molecular clock. We present here a novel star contraction algorithm which rigorously identifies starlike nodes (clusters) diagnostic of prehistoric d emographic expansions. Applied to the Asian and Papuan data, we date the ou t-of-Africa migration of the ancestral mtDNA types that founded all Eurasia n (including Papuan) lineages at 54,000 years. While the proto-Papuan mtDNA continued expanding at this time along a southern route to Papua New Guine a, the proto-Eurasian mtDNA appears to have drifted genetically and does no t show any comparable demographic expansion until 30,000 years ago. By this time, the East Asian, Indian, and European mtDNA pool,,; seem to have sepa rated from each other, as postulated by the weak Garden of Eden model. The east Asian expansion entered America about 25,000 years ago, but was then r estricted on both sides of the Pacific to more southerly latitudes during t he Last Glacial Maximum around 20,000 years ago, coinciding with a chronolo gical gap in our expansion dates. Repopulation of northern Asian latitudes occurred after the Last Glacial Maximum, obscuring the ancestral Asian gene pool of Amerinds.