【作者】 赵永斌；

【导师】 周慧；

【作者基本信息】 吉林大学 ， 生物化学与分子生物学， 2011， 博士

【摘要】 汉族是世界上人口最多的民族,也是中国的主体民族,对于汉族的起源一直是历史学家、考古学家、人类学家以及遗传学家关注的重点。通常认为,汉族起始于活跃在中原地区的华夏族,后者经过与其他民族融合之后,至汉代初步形成以汉族为称谓的民族,此后又不断与周边民族发生融合,最终形成现代汉族。然而,汉族的发展过程异常复杂,现有研究还不足以全面了解它的详细过程,古DNA研究可以直接探寻汉族的前身华夏族以及每个历史时期的汉族人群的遗传结构,从而构建汉族发展的时空网络,了解汉族群体演变过程中遗传结构的变化情况,为阐明汉族发展历程提供重要的遗传学依据。本研究通过对三处遗址的人类遗骸——山西横北村西周时期古代人群、宁夏彭阳东周时期古代人群、青海陶家寨东汉魏晋时期古代人群的线粒体DNA进行研究,结合中国现代人群以及其他北方古代人群的线粒体DNA研究结果,以遗传学的视角对汉族的母系起源作了初步探索。第一、成功从68例横北村古代人类遗骸中获得52个真实可靠的线粒体高可变Ⅰ区序列,归属于46个单倍型,13个单倍型类群,分别为A、B、C、D、F、G、M7、M8、M9、M10、M*、N9a以及Z。单倍型类群频率分析表明,横北村古代人群各种频率分布与现代汉族人群相类似。主成份分析显示横北村古代人群与北方汉族紧密聚类在较小的区域内。共享序列分析表明在中国人群当中,与横北村古代人群共享个体数所占比例最高的是现代北方汉族,同样,在横北村古代人群中有最多的个体与北方汉族共享同一单倍型。分子差异度分析显示横北村古代人群与现代北方汉族的Fst值最小,甚至为负值,P值远大于0.05,两者表现出特别近的遗传关系。人群混合度分析中,以横北村古代人群和古代匈奴人群作为祖先人群、现代北方汉族作为后代人群进行分析,横北村古代人群对现代北方汉族的人群混合度数值都比较大,达到了0.709134(MBE)和0.8290(MRH),分别以横北村古代人群和古代匈奴人群作为祖先人群、北方少数民族作为后代人群进行分析和以横北村古代人群和南方少数民族作为祖先人群、现代南方汉族作为后代人群进行分析,横北村古代人群对北方少数民族和现代南方汉族的人群混合度数值都较小,说明横北村古代人群与现代北方汉族的遗传关系比横北村古代人群与北方少数民族和南方汉族的遗传关系较近。所有遗传学分析结果都一致表明横北村古代人群同现代北方汉族的遗传结构非常相似,暗示3，000年前的中原地区居民对现代北方汉族具有母系遗传贡献。另外,虽然横北村古代人群中存在多种葬俗,人群也可分为有殉人的墓主、无殉人的墓主和殉人三大类,但是各种遗传分析显示横北村古代人群内部不存在明显的母系遗传结构差异。第二、成功从6例宁夏彭阳古代人类遗骸中获得真实可靠的线粒体高可变Ⅰ区序列,归属为6个单倍型,3个单倍型类群,分别为C、D4和M10。为了研究本样本的单倍型在现代人群中的分布,在东亚和北亚人群已经发表的线粒体数据库中搜索了共享序列,结果这6个样本均找到了相应的共享个体。总体来看,这些样本的共享个体大多来自于北方游牧畜养民族起源的北亚人群和中国北方少数民族。进一步通过中介网络分析探讨彭阳古代人群的种族归属问题,单倍型类群C中,北方现代汉族个体大多聚集在一个聚类簇上,样本PW4与现代北亚人群、中国北方少数民族以及古代游牧畜养人群聚类在一起。单倍型类群D中,所选用的几个人群大都混合在一起,很难将他们清晰的分辨开来,但比较明显的是,样本PZ2与PW6只与中国北方少数民族和北亚人群共享同一节点。单倍型类群M10中,没有古代游牧畜养人群。样本PW7与北亚人群及北方汉族共享同一节点。总的看来,这6个样本的共享人群在北亚人群和中国北方少数民族中均有发现,而且有些个体的共享人群只来源于或多数来源于游牧畜养起源的民族中,这些结果表明邻近中原地区的彭阳古代人群可能来自于北方游牧畜养民族。第三、成功从46个青海陶家寨古代人类遗骸中得到了43个真实可靠的线粒体高可变Ⅰ区序列,归属为24个单倍型,8个单倍型类群,分别为A、B、D、F、M10、M*、N9a和Z。基于线粒体单倍型类群频率分析,陶家寨古代人群与现代北方汉族及藏缅人群具有较近的遗传关系。主成份分析图中,陶家寨古代人群可以与北方汉族划分为一个聚类簇,同时也与一少部分藏缅人群距离非常近。中介网络图中,无论在北方主导的单倍型类群还是南方主导的单倍型类群中,陶家寨人群总是与大多数的藏缅人群和汉族聚集在一起。分子差异分析表明陶家寨人群与藏缅人群的Fst最小,甚至为负值(-0.00095),P值远大于0.05,另外,陶家寨人群与北方汉族、南方汉族的Fst分别为0.00359和0.00406,P值都大于0.05,说明他们之间差异不显著。这些结果表明陶家寨古代人群与藏缅人群和汉族具有较近的遗传关系。由于古代氐羌人群是藏缅人群的主要母系来源之一,陶家寨又地处古代氐羌人群聚居地,该墓葬群属于同时期的汉文化,由此推测古代氐羌人群是汉族人群的一个母系基因贡献者。第四、对各种古代人群线粒体DNA分析表明,在所选的古代人群中同现代北方汉族遗传结构最为相似的是3,000年前居住于中原地区的横北村古代人群,而其他古代人群包括青海陶家寨古代人群和宁夏彭阳古代人群,相对于横北村古代人群来说,他们与现代北方汉族遗传关系略远一点,但是他们或多或少都与现代汉族存在着单倍型共享的情况。基于以上分析结果,结合历史记载,我们得出如下汉族发展历程假设：远古时期,若干氏族部落相互融合,逐渐在中原地区形成华夏族,后者又不断与周边民族融合,至汉代形成以汉族为称谓的民族,此后又继续向外扩张并与周边民族融合,最终形成现代汉族。由于农耕文化远远先进于周边地区的游牧渔猎文化,华夏族及其后裔的人口数量远远多于其他人群,以后的民族融合中,汉族群体一直占据主导地位,这使得其遗传结构基本保持稳定。后期汉族大规模向南方地区迁徙,并与南方土著民族发生融合,母系基因结构发生了一定变化,最后形成了北方汉族和南方汉族在母系方面存在一定差异的局面。更多还原

【Abstract】 Han Chinese is the largest single ethnic group in China and in the world. Recently, it has attracted extensive interest among scientists such as historian, archaeologist, anthropologist, paleoanthropologist and geneticist, regarding where it originated and how it developed. In general, Han Chinese can trace its origins to Huaxia who formed in the central plain. Following admixture with neighboring natives, Han Chinese became much the largest of the 56 officially recognized ethnic populations in China. Further research should be conducted, however, because Han Chinese formed through a long history and a complex process. The study of ancient DNA may be better to present the Han’s evolution, immigration and even expansion of Han culture because of the directly tracking temporal genetic changes. In this study, ancient people from Hengbei site (West Zhou period), Pengyang site (East Zhou period) and Taojiazhai site (East Han period) were analyzed in maternal Lineage. We have attempted to explore the origin of the Han Chinese.Firstly,52 reproducible mtDNA HVRI fragments were obtained from 68 ancient Hengbei people, and they were attributed to 46 haplotypes which belong to 13 haplogroups such as A, B, C, D, F, G, M7, M8, M9, M10, M*, N9a and Z. The frequency of haplogroups in ancient Hengbei people is similar to that in the northern Han Chinese. In the plotting of PCA,Hengbei ancient people clustered with northern Han Chinese in a small district. Sharing population analysis showed that there were the most number of northern Han individuals among Chinese ethnics who shared same haplotypes with ancient Hengbei people. Likewise, the frequency of people who shared same haplotypes with northern Han Chinese is highest in ancient Hengbei people. According to the analysis of molecular variance approach, the Fst between ancient Hengbei people and northern Han Chinese was the lowest (-0.00244). and p value was more than 0.05, indicating the close relationship between ancient Hengbei people and northern Han Chinese. The relative contribution of the two parental populations (ancient Hengbei people and Egyin Gol Valley ancient people, ancient Hengbei people and Egyin Gol Valley ancient people, ancient Hengbei people and southern minorities) in three populations (northern Han Chinese, northern minorities, southern Han Chinese) was estimated by two different statistics (MBE and MRH). The results showed that the ancient Hengbei people contribution to the northern Han Chinese was much higher than that to the northern minorities and southern Han Chinese. Over all. the ancient Hengbei population was close to the northern Han Chinese in maternal Lineage, indicating a stable maternal genetic structure in northern Han Chinese since 3,000 years ago. Again, there was no distinct difference between owners of the tombs with Immolated people, owners of the tombs without immolated people and immolated people.Secondly,6 reproducible mtDNA HVRI fragments were obtained from 6 ancient Pengyang people, and they were attributed to 6 haplotypes which belong to 3 haplogroups such as C, D and M10. To understand the geographic distribution of the sharing populations, the six haplotypes from our study were used as queries to search for sharing populations in the published data of modern people across East Asia and Siberia. The result showed that most of people who shared with ancient Pengyang people were northern Asians and northern minorities of China who can trace their origins to nomads. According to network analysis, in haplogroup C, the Han Chinese originating from the farming people are concentrated in one group. Meanwhile. PW4 is clustered into another group with minorities in northern China, northern Asians and ancient nomads. In haplogroups D4 and M10, the ancient Pengyang people consistently occupy the same nodes as northern Asians, northern minorities of China and ancient nomads. All analysis showed that ancient Pengyang people, living near the central plain area, may originate from nomads.Thirdly,43 reproducible mtDNA HVR-I fragments were obtained from 46 ancient Taojiazhai people, and they were attributed to 24 haplotypes which belong to 8 haplogroups such as A. B, D, F. M10, M*,N9a, and Z. The ancient Taojiazhai people are close to the Han Chinese and some Tibeto-Burman populations in terms of the frequencies of mtDNA haplogroups. The ancient Taojiazhai population pooled into the northern Han Chinese group and was also close to a few Tibeto-Burman populations in plotting of PCA. In the Maximum Parsimony trees, most of Taojiazhai samples were always nearby the Tibeto-Burman populations and Han Chinese. AMOVA was used to evaluate maternal genetic differentiation between ancient Taojiazhai people and other populations. The Fst between Taojiazhai people and Tibeto-Burman population was the lowest (-0.00095), and P value was more than 0.05. In addition, ancient Taojiazhai people and Han Chinese (including northern Han and southern Han) were also not significantly different (Fst value:0.00359 and 0.00406, P:0.05). All studies showed that the ancient Taojiazhai people bore a very high similarity to the Han Chiese and those Tibeto-Burman populations who had high contribution of the Di-Qiang populations. Together with the geographic location and culture of Taojiazhai site, it means that the ancient Di-Qiang populations may be one of the genetic contributors to the Han Chinese people.Lastly, according to the comparison among Han Chinese and the ancient populations in this study and previous studies, ancient Hengbei people was closer to the northern Han Chinese than other retrieved populations in maternal Lineage. However, besides ancient Hengbei people, there were many individuals from other ancient populations shared same haplotypes with northern Han Chinese, indicating that neighouring populations had assimilate into Han Chinese.In conclusion, according to the results maintioned above, we proposed a development process of Han Chinese. Following the confluences of many ancient tribes, Huaxia had formed in central plain. Then, Huaxia people migrated to peripheral area and assimilated neighboring populations as well as absorbed many other cultures. Until Han Dynasty, Huaxia civilization developed into a tribe known as Han Chinese. Like Huaxia, Han still integrated with numerous tribes or ethnic groups gradually following its expansion. Because of its advanced agriculture, technology, and culture, number of Huaxia (or Han Chinese) people was more than that of neighouring population. So, Huaxia (or Han Chinese) played a predominant role in the mixture of populations, which leads to a stable maternal genetic structure in northern Han Chinese since 3,000 years ago. When Han Chinese migrated from the central plain to the southern China and mixed with southern natives, which shapes a differenation between northern Han Chinese and southern Han Chinese in maternal Lineage.更多还原