Ancient Population Of Mtdna Polymorphisms

The development of modern human genetics has greatly promoted the evolution studies of human populations. Nevertheless, many conclusions were drawn from the study of present people, which might only reflect the past events indirectly. More direct evidences from the ancient remains are necessary. The ancient DNA study hopefully opens a new perspective for the full use of the abundant archeological resources in China. To better understand the genetic characters of the ancient Chinese people and provide new clues for the origins and migrations of these present populations, we collected 581 human remains belonging to 20 archeological sites in 10 provinces of China. Efforts were made to extract DNA from these ancient samples in a laboratory dedicated to ancient DNA work. aDNAs were successfully extracted from 221 remains and were subjected to the mtDNA analysis. Moreover, for comparisons, we also conducted DNA extraction and mtDNA analysis to the blood samples collected from some present populations in the above provinces and collected a large amount of published mtDNA data.The ancient DNA analysis of the remains from the northwest region of China shows the coexistence of West and East Eurasian mtDNA characters in Xinjiang as early as Bronze Age, which is consistent with abundant archaeological discoveries in this area. The subsequent comparisons between the genetic and physical anthropological results provide unequivocal evidence that supports the prehistoric genetic admixture between West and East Eurasians before the rise of Silk Road (2nd century BC). The East Eurasian mtDNA characters in Xinjiang may come from the adjacent ancient populations in the northwest region. There was no West Eurasian mtDNA lineages found at the archaeology sites east to Xinjiang in China before the Qin dynasty. However, considering the limited samples in ancient DNA studies, it suggests that the genetic admixture between West and East Eurasians in the regions east to Xinjiang at that time is far less, if not absent at all. Through the direct and indirect contact, such early demographic events detected in Xinjiang may finally bring influence to the genetic pools of the subsequent generations of populations in or near this area.The mtDNA data of ancient northwest region people and ancient Shandong people show difference by comparison. Further analyses indicate that part of the difference is caused by the South to North migration in or before the Zhou dynasty. Later, the culture and genetic influence of Han and other nomadic tribes coming from central and north China might have brought major shifts in the composition of the resident population in Shandong. These migrations may also influent the ancient Japanese and cause the Jomon period to the Yayoi period transition. And the mtDNA haplogroup distribution also suggest some earlier migrations from the continent to the Japanese archipelago occurred during the Jomon period.A markedly genetic difference of northern and southern ancient people in China was revealed by their mtDNA haplogroup distributions, which also can be seen by the comparison of present South and North populations. Through the data analysis, some clues were provided to illuminate the relationships between the ancient South tribe members and the present Chinese people, which may also shed some light on the understanding of their origins.