Paleogenomic Research Of Ancient Populations From Northern China

The Eurasian Steppe,covering a vast land and stretching from Carpathian Mountains and the coast of the Black Sea in the west to Mongolian Plateau in the east,serves as a natural passage for crossing the Eurasian Continent with length of about 8000 miles.With the common subsistence and similar customs,all the nationalities living in the Eurasian Steppe plays an irreplaceable role in the history of the economic and culture exchanges between the East and the West.Locating at the southeastern part of the Eurasian Steppe,North China,with many historical events happening in this stage,situated at the border of the northern nomadic people and the southern people with agricultural civilization.Every contact between the nationalities in north and those in Central Plains all provides significant influences on the Chinese history and even the world history.Therefore,the study of formation of the genomics of the ancient people in North China provides a very important significance for acquiring the knowledge of the people in the East and the West,the cultural exchanges between them,as well as the origination of Chinese civilization.The improvement of DNA Sequencing technique and ancient DNA study makes it possible for researchers to detect the genomic sequencing of ancient humans.Due to it contains a mass of genetic information;the genomic data can avoid the deviation of past study based on haplotype frequency analysis,and acquires genetic constitutions of different groups of people,offering more convincing evidences to the origination and development of populations.With amount of paleogenome study in Europe,European researchers achieved clear knowledge on the population migration and expansion as well as the admixture among different human groups in various periods.The paleogenome research has just caught on,and there is no available data in China.With more and more Chinese ancient human genome data released in the future,predict that people in China we will confidently have a clearer cognition on the prehistory population.In this study,two cemeteries were selected as the study objects which are both representative in the types of people and region.The one is the Bronze Age site of Xiabandi in the Xinjiang Province,and the other is the Houtaomuga site across the Mesolithic age to the Liao-Jin period in Daan City,Jilin Province.Combining with data analysis from both of modern and ancient populations from surrounding area,the author studies the objects from three aspects including the mitochondrial genome,the genome wide capture(including the locus of Y chromosome),and the whole gemome sequencing,in order to provide the evidence of genomics for acquiring the knowledge of the genetic structure of the northerners in different periods and the situation of those people's cultural exchanges with surrounding areas.First,16 mitochondrial genome sequences,which are proved to be authentic and reliable,are achieved successfully from 31 ancient individuals from AII cemetery in the Bronze Age Xiabandi site,Xinjiang province.These sequences belongs to 14 different haplotypes,which are U4c1 a,U1a1c,I1 b,H5b,U4a1,H11 b,HV,U2e3,H6a1 a,U2e1,I4 a,R1b,U2e2a4 and T2a1b1.These haplotypes are all from the western part of Eurasia,and almost all the haplotypes can find the sharing haplotypes in the mitochondrial gene pool of people steppe in the Bronze Age,thus the result demonstrates that the Xiabandi population is origined from the western part of Eurasia and they may be have close relations with nomad in steppe.The principal component analysis of the distribution frequency of the mitochondrial haplotypes also shows that the people in Xiabandi have a very close genetic relation with Bronze Age people in Eurasian steppe.The combination of the founder test and the theory of mitochondrial molecular clock suggest that the time when the people of Xiabandi apart from their ancestors,is about 4500 years ago.Therefore,the time of migration and the source of mitochondrial haplotypes show that the most possible origin of the Xiabandi people is the steppe people in the Bronze Age(the people related to the Yannaya culture).With the extension of those steppe people,they arrived in the Pamir Mountains.In addition,we also performed the genome-wide capture for M29 individual in the Xiabandi site,also included the locus of Y chromosome.The Y haplotype chromosome of M29 is R1a-Z94,and the formation time of this haplotype is no earlier than 5000 years ago.This haplotype had been found in an ancient European individual from 4900-4500 years ago with 63.7% gene from Yamnaya population of Eurasian steppe and 36.3% from Neolithic Central European.The results suggest that the haplotype of R1a-Z94 originates from Europe.The extensive distribution of R1a-Z94 is due to fast expansion of steppe people in Yamnaya culture,that research result corresponds with the common academic viewpoint,which shows the Indo-Iranian's rapid extension from Eurasian Steppes to South Asia.The phenotypic analysis of autosome shows the same result which the Xiabandi people is most likely to be European with blond hair,blue eyes and light skin.Due to the situation of the autosome locus deficiency in the public database leading to low resolution ratio of the autosome,however,the results from PCA and admixture analysis suggest that the Xiabandi people has a very close genetic relation with those of the current Eurasia Steppe people and those related with the Yannaya culture in Bronze Age.Based on above research results,it is confirmed that the Bronze Age Xiabandi population originated from the Eurasian steppe in Bronze Age and their migratory motivation may have connection with the rapid expansion of the Indo-Iranian linguistic people.Second,the whole-genome data are successfully acquired from 20 individuals ranging from Mesolithic Age to Iron Age in Houtaomuga of Daan City,Jilin Province.And the sequencing depth of the samples from Mesolithic Age is 34 X,providing a high quality referential genome for the future research in ancient DNA.10 mitochondria haplotypes are gained from samples of these 20 individuals,that is,D4h1,D4b1b2,D4e5 a,A,M5a2a3,B4c1a2,C4a2,F1a1 c and G2a1.Those haplotypes are very common in the north part of Asia.The principal component analysis based on whole-genome data shows that there is fine cluster with both intrapopulation of different periods in Houtaomuga and the difference modern population(such as people in Elunchun and Hezhe)in the same geographic area.This result suggests that the genetic structure of people in Nen River valley has not change much since Mesolithic Age,and those people reveals strong genetic continuity.In order to verify the genetic connection of people in Nen River basin in time gradients,f3-statistics method was applied to inspect the gene flow of those people.It comes to the same result as that of the principal component analysis,which is strong gene flow between ancient and extant people in Nei River valley.On account of the f3-statistics method is vulnerable to the bottleneck effect of population,the f4-sattistics method was performed to test the gene flow of those people.The result shows that the absolute value is far less than 3,demonstrating that there is no obvious change in the crowd pattern of the Nen River basin in different periods from Mesolithic Age until now.The analysis of the people admixture indicates that the people in whole Nen River basin sharing a very similar genetic structure from Mesolithic Age until now.Low frequency of a genetic element of modern Russian Far East population has been detected from the samples of individuals in Mesolithic Age of Houtaomuga.However,there is no sign of this genetic element in samples ranging from Neolithic Age to Early Iron Age,indicating that this genetic element originates from admixture with Far East population before the Mesolithic Age.In the later period,no further admixture leads this element to be diluted gradually and disappear in the end.Geographically,the Nen River valley is a close to Liao River valley,which accept the northward movement of agricultural population from the central plain,and had been undergone many times of replacement in population structure and subsistence strategy since the Neolithic period,However,the people in Nen River basin has been maintained a high degree of genetic connection from Mesolithic Age until now.On the one hand,it is maybe because of its unique geographic location leading to a relative isolation than other places,along with the dry and rainless environment is not suitable to develop nomadism and agriculture.On the other hand,the rich resources of fishery and forest provides abundant food source for the local people living the hunting-gathering-fishing way of life.The physic-geographical environment of North China which posses a vast area determines that there are significant differences in the origination and formation of people in northern China.The people in Northwest China,especially the people in Xinjiang area,have a pretty close relation to the people in Bronze Age of Eurasian Steppes and of Central Asia.In Northeast China,the Nen River basin indicates a high degree of regional continuity,with no external gene interfering in and no population replacement.