As discussed above, ADH1B rs1229984 MAF shows very strong differences between Asian and non-Asian populations. Figure 5 reports the allele frequencies in the 53 populations from seven continental groups of Human Genome Diversity Project (available at http://hgdp.uchicago.edu/cgi-bin/gbrowse/HGDP/; [Li and others 2008]). Initial candidate gene studies highlighted that variation in ADH gene cluster presents unusual patterns of linkage disequilibrium and diversity in Asian populations, and, in particular, ADH1B rs1229984 frequencies are not driven by random genetic drift but are instead attributable to positive selection in these human groups [Han and others 2007; Li and others 2007; Osier and others 2002]. Further analyses determined that the emergence of the ADH1B rs1229984 minor allele occurred about 10,000~7,000 years ago, which coincides with the time of origin and expansion of neolithic agriculture (rice domestication) in southern China [Peng and others 2010]. However, a subsequent study demonstrated that the expansion of the selected ADH1B rs1229984 haplogroup is more recent, around 2,800 years ago [Li and others 2011b]. Furthermore, although ADH1B rs1229984 originated in the ancestors of Sino-Tibetan populations and the high diversity is present in
