Mapping Human Genetic Diversity in Asia

The HUGO Pan-Asian SNP Consortium ("Mapping human genetic diversity in Asia," Reports, 11 December 2009, p. 1541) suggested that the Asian continent was populated through a single migration event. Genetic analysis of Asians, however, is a much more complicated process. There clearly existed a northern migration route to East Asia through Central Asia, which was not actively investigated in this effort (1, 2). Although ascertainment bias in the phylogeny might be ruled out under extreme ascertainment scenarios, the evidence for the southern coastal route is not strong given the paucity of northern East Asians (EAs) in the "fabulous data set."

Numerous previously published papers reported a distinct genetic difference between northern and southern EAs, reflecting the various struggles and competitions that took place throughout history (2, 3). Y. Xue et al. proposed that the northern populations started to expand before the last glacial maximum (LGM) 21 to 18 thousand years ago in the Mammoth Steppe (2). Even after the LGM, a landscape then dominated by swamps in the present Yellow River region might have acted as a directional barrier to gene flow northward, just as the Himalayas did (4). Later northern EAs, who possessed superior combat assets, subjugated the southern EAs, even though the latter possessed higher productivity because of familiarity with plant cultivation (5). Koreans, for example, possess both the northern and the southern Asian lineages (55% and 45% contribution, respectively) on the basis of Y-chromosomal markers (6). The north–south population structure in East Asia, however, is a continuum rather than a sharp division (2). The spread of culture and language was possible through mass movements of people, supporting the demic diffusion model (5). Further studies using climatology, linguistics, and anthropology, as well as genetics, should be followed if research at the HUGO Pan-Asian SNP Consortium is to create a viable and complete phylogenetic explanatory model for EAs, rather than the inadequate one that gives, at present, only a partial interpretation.

Jin Hyuk Yang

Department of Laboratory Medicine, Korea University Medical College, Seoul, Korea.

Sung Nam Kim

Academy of Korean Studies, Gyeonggi-do, Korea.

References

1. J. Diamond, P. Bellwood, Science 300, 597 (2003).

2. Y. Xue et al., Genetics 172, 2431 (2006).

3. J. Chen et al., Am. J. Hum. Genet. 85, 775 (2009).

4. T. Gayden et al., Am. J. Hum. Genet. 80, 884 (2007).

5. B. Wen et al., Nature 431, 302 (2004).

6. K. D. Kwak et al., Int. J. Legal Med. 119, 195 (2005).