Molecular Genetic Analysis Of Khitan Population In Liao Dynasty

Khitan was an ancient nomadic ethnic population in northern China and came ofthe boundless grasslands upriver of the Liao River. The Khitan Kingdom wasestablished in 907, then changed its national title to Liao forty years later. In 1125,Liao Kingdom was defeated by Jurchen. At that time some Khitans moved towardsthe west to Central Asia and established a new empire called Western Liao, whichwas conquered by Mongolia in 1218. Khitan has completely disappeared from all thehistorical recordation till the end of Yuan dynasty. Khitan had profound influences atthat time on the politics, the economy and the culture of China, North Asia andCentral Asia, although Khitan has not existed for a long time. Therefore, it issignificant on the history and archeology to study on Khitan. In this study, wediscussed on the topics of Khitan's genetic structure, race, origin, and descendant bymeans of molecular biology methods. Some important clues would be supplied to thestudies of Khitan's history, culture, and especially the disappearance.In this study, the skeletons of human remains were collected from thenecropolises of Xiao he's family, Yelv yuzhi's family and shanzuizi, as well as thetombs of Shangdu, Jianshan and Turki. The HVR I of mtDNA in these skeletonswere extracted, amplified, sequenced. Genetic analysis of the Khitan population inLiao dynasty has been done on the topics of genetic structure, race, origin anddescendent.⑴ Both the relationships and the history trends as well as the sequences ofindividuals in the Khitan population were analyzed. The analyses on the mutated sitemutated rate, haplogroup and shared sequences of individuals' sequences show thatthe Khitan population was close to Asia populations. Besides, the researches on therelationships in Khitan population indicate that the samples from necropolis of Xiaohe's family were closely related to that from Shangdu tombs. In the same way, thesamples from necropolis of Yelv yuzhi's family were closely related to that of Turkitomb. And the samples from Shanzuizi necropolis were closely related to that fromJianshan tomb. The samples of different tombs were classed into noble and plebeian,early phase and middle-late phase or east and west. It seems that the geneticdifferences between noble and plebeian, or between early phase and middle-latephase were remarkable. It probably attribute to the policy of intermarriage betweenYelv and Xiao and the gene flow from other populations. However there wasn'tmuch difference between the east and the west population of Khitan. Mismatchdistributions were computed and the unimodal distributions were interpreted as signsof demographic expansions. In parallel, the raggedness index was generally lowerthan 0.05, negative values of Fu's Fs and Tajima's D that differ significantly fromzero, also supported these patterns of demographic history.We also researched on the samples of Yelv yuzhi's family and Xiao he's familyin this paper. The results indicated that remarkable difference existed between thetwo families' samples. It is implied that there was not much gene relationshipbetween the two families although Yelv yuzhi's family belonged to the emperor'sfamily and the Xiao he's family belonged to the empress' family. The differencebetween the two families's samples implied the genetic relationship of the twofamilies and probably related to the different phases they lived in Liao dynasty.Furthermore, the skeleton in Turki Liao tomb, which was said to belong to a Khitannoble woman and probably a Khitan princess, was analyzed. Therefore, the samplesfrom Yelv yuzhi's and Xiao he's families were employed to contrast with that ofTurki tomb. It was observed that the sample of Turki tomb was located in the regionof Yelv yuzhi's family in the phylogenetic tree. Moreover, the sequence of the samplefrom Turki tomb was quite similar to that of the sample 15 from Yelv yuzhi's familyexcept for only difference in a nucleotide site. It implied that there were closeheredity relationships between the samples of Turki tomb and Yelv yuzhi's familynecropolis. The noble identity for the skeleton from Turki tomb was approved andthe possibility of princess for the skeleton was demonstrated.⑵ To confirm the ethnic group of Khitan, fourteen modern contrastedpopulations in North Asia, East Asia, and Central Asia were chosen. The result ofmultidimensional analysis shows that Khitan population was more closely related topopulations in North Asia than to that in East Asia or Centeral Asia.⑶ There were two opinions that Khitan came from Xianbei or Xiongnu. One ofthe purposes in this paper was to confirm the origin of Khitan. We contrasted Khitanpopulation with Xianbei, Xiongnu and all of the eight modern populations. Theresults of phylogenetic and multidimensional analysis show that the geneticrelationship between Khitan and Xianbei was the closest. However, the geneticrelationship between Xiongnu and some modern North Asia populations, such asOuter Mongolia, Inner Mongolia, Buryat etc., was closer than that between Xiongnuand Xianbei, or Xiongnu and Khitan. Above-mentioned conclusions support thatKhitan origined from Xianbei and indicate that there was no original relationshipbetween Xiongnu and Khitan at the same time.⑷ Arguments focus on the Khitan's descendants now. We discussed thisquestion through molecular genetic analysis based on the archaeology, history andethnology literatures. The results show that most of Khitans were assimilated byMongolians after the fall of Liao dynasty. The direct descendant of Khitan has notbeen found in modern populations. It is probably that Daur is not the descendant ofKhitan.In this paper, the ancient DNA sequences of Khitan population were studied.The analysis of genetic structure, race, origin and descendent etc. developed thestudies of Khitan on molecular genetics, and provided the clues to the history,archeology and ethnology. By analyzing the origin and descendant of Khitan, weobtained some molecular genetic evidences on the disputed questions of the Khitanstudy. By discussing the nobles and race of Khitan, the results of archeology andphysical anthropology were validated and complemented. Furthermore, byresearching the genetic structure of Khitan, we obtained more knowledge of Khitanpopulation on molecular genetics.