Y-chromosomal DNA variation in East Asia

Xue et al 2004

East Asia has been inhabited by modern humans for > 50,000 years and now holds more than one quarter of the world population. Genetic analysis using classical markers identified a major north-south distinction (Cavalli- Sforza et al. 1994), which may reflect separate origins of northern and southern populations from different migrations out of Africa. The Y chromosome provides high-resolution male haplotypes and thus an opportunity to investigate male-specific history. We have typed 1012 individuals from 28 populations in China, Mongolia, Korea and Japan with 45 binary markers (mostly SNPs) and 16 microsatellites from the Y chromosome. SAMOVA analysis of Y-SNPs was used to identify the geographical divisions that apportion the maximum amount of genetic variation between groups (Dupanloup et al. 2002). It did not show the traditional north-south division, but identified small groups of distinct populations, mainly in the south. Why should Y-chromosomal variation show a different structure from that of the rest of the genome? We have investigated the distribution and time- depth of individual haplogroups. For example, haplogroup O is largely confined to East Asia and one of its subdivisions, O3, is widespread and common in China. A subset of these chromosomes, O3/-d, is concentrated in southern China, particularly in the two Yao populations which formed one of the major SAMOVA divisions. The time depth of the O3/-d lineage was estimated at approximately 5,900 (4,500 - 8,200) years from its microsatellite variation using the program BATWING (Wilson and Balding 1998), so must have spread after this date. A second common haplogroup is C, and C3c chromosomes are concentrated in northeastern China where they are present at highest frequency in the Oroqen population, another of the major SAMOVA divisions. A substantial subset of them appear to have expanded very recently, < 900 years ago. These results suggest that East Asian Y-chromosomal variation has been substantially reshaped by recent events within Neolithic and historical times