Population Admixture in East Asia
In East Asia, most of the populations that have been studied are thought to be relatively homogeneous. Most people identify themselves with one particular ethnic group, but in fact, we are highly mixed. A report from the HUGO PanAsia SNP Consortium, which was published in Science in 2009 [68], revealed a picture of prevalent gene flow among Asian populations. As a collaborative effort of 93 scientists from 10 countries, this study conducted the first large-scale and genomewide study on the genetic diversity of 73 Asian populations, representing a broad geographic sample of the major ethnic groups and linguistic families in Asia.
Considerable gene flow among Asian populations was observed amongst sub-populations in these clusters, including those groups believed to practice endogamy based on linguistic, cultural, and ethnic information. In fact, most populations studied show evidence of admixture in population structure analyses. For example, the Han Chinese have grown to become the largest ethnic group today, in a demographic expansion that has occurred mostly within historical times. The analysis in this study reveals that the 6 Han Chinese populations show varying degrees of admixture (Fig. 4) between a northern 'Altaic' cluster and a 'Sino-Tibetan/Tai-Kadai' cluster, which is most frequent in the ethnic groups sampled from southern China and northern Thailand. Finally, most of the Indian populations showed evidence of shared ancestry with EUR populations, which is consistent with our understanding of the expansion of Indo-EUR speaking populations (Fig. 4).