The Y Chromosome Revealed By Early Humans Into East Asia And East Asian Populations, The Characteristics Of The Formation Process

Since the naissance of humankind,there is endless work to probe into the selves of their own,especially the origin of modern human which can always arouse the enthusiasm of exploration and incessant controversy.In the studies of molecular anthropology,in-depth study of genome injected new vitality into the search on the evolution of human beings:the evolutionary study of genes was impelled by the research on the variations of the non-recombining portion of the Y-chromosome (NRY),thus the phylogenetic tree can be constructed from the genetic aspects of paternal structure to analyze the structures and relationships among populations, elucidating the phylogenetic relationships between the populations all over the world, which is used to reconstruct the phylogenesis of populations combined with the results from other anthropotogic fields.Though the origin of East Asians is still controversial,a rapid accumulation of molecular anthropological studies of the populations in and around East Asia resulted in the discovery that most of the Y chromosome lineages of East Asians came from Southeast Asia.However.little investigation has been conducted on the Southeast Asian populations which are supposedly the ancestral populations of East Asians. Therefore,the supposed migrations from Southeast Asia into East Asia and their roles in shaping genetic structure of East Asian populations are yet to be understood.Here we present the Y chromosome data of 1,652 individuals from 47 populations of Mon-Khmer(MK) and Hmong-Mien(HM),which distribute primarily across Southeast Asia and extend into East Asia.Haplogroup O3a3b-M7 which can only be found in these two groups indicates a strong tie between them.The short tandem repeat(STR) network of O3a3b-M7 displayed a hierarchical expansion structure,with the Mon-Khmer haplotypes in the center/entrance,the Hmong-Mien and the Tibeto-Burman haplotypes distributed further away from the entrance.Moreover, haplogroup O3a3c1-M117 shows the similar network structure as O3a3b-M7 though the distribution of O3a3c1 is not as specific as O3a3b.These patterns indicate a unidirectional diffusion from Southeast Asia into East Asia,which might have resulted from the slow and even migration of early modern humans' carrying these two haplogroups from Southeast Asia to East Asia by many small bottle-neck effects. The age of O3a3b-M7 was estimated to be approximately 15,300 years while that of O3a3c1-M117 is a bit older around 20,000 years,followed by the emergence of the ancestors of HM lineages out of MK and the unidirectional northward migrations into East Asia.The origin of Peninsular Daic is another focus of attention for us to study.The Daic ethnic group including Thai and Lao people has the largest population in the Indo-China Peninsula.Not like the Mon-Khmer native to the Peninsula,the Daic populations were considered to be migrants from the north.However,the origin of its cukure and population remains controversial.In this study,we compared the Y chromosome diversity of the Peninsular Daic to those of Chinese Daic and the Mon-Khmer populations to reveal the origin of the Peninsular Daic populations.We typed twenty single nucleotide polymorphisms(SNPs) and seventeen short tandem repeats(STRs) in the non-recombining region of Y chromosomes sampled from nine Daic populations from the Republic of Lao.Principal component analysis and NETWORK construction showed that very few Y lineages(haplogroup O1 a only) of the Peninsular Daic came from the Chinese Daic,but most of the other patrilineal lineages originated in the Mon-Khmer people.Therefore,we demonstrated that the Daic culture may have been carried by finite people from the Daic populations in China to the Indo-China Peninsula and subsequently assimilated many native Mon-Khmer people.