Detailed information of molecular anthropology

Molecular anthropology is a branch of anthropology, which uses the molecular analysis of human genome and DNA genetic information to analyze many aspects and levels of human origin, national evolution, ancient social and cultural structure and so on. It is a new interdisciplinary subject.

In the past, before the rise of molecular anthropology, it was very limited to study history and explore the origin of nations only by limited historical materials and archaeological discoveries. Historical materials, in particular, are very limited and not necessarily true. Therefore, the rise of molecular anthropology will greatly break these limitations, reveal a more real and accurate history to people, and thus analyze the origin of a nation more clearly. Molecular anthropology has solved many anthropological problems with DNA materials and computational biology methods.

Basic Introduction Chinese Name: Molecular Anthropology mbth: Molecular Anthropology Function: Exploring the disciplinary basis of human origin and national evolution: Basic introduction of computational biology (bioinformatics), and basic introduction of human origin theory, haploid genetic points, mitochondrial DNA, Y chromosome, DNA inheritance, hypothesis, unreliable recombination, Han ancestors, population mobility and southern Han nationality. Molecular anthropology is a branch of anthropology, which uses molecular analysis of human genome and DNA genetic information to analyze human beings. It is a new interdisciplinary subject. The main method is to compare DNA or protein sequences, and the early methods also include serological comparative research. By examining the DNA sequences of different specific residents, scientists can judge the genetic relationship between or within specific residents. Anthropologists judge whether different people belong to the same genome or originate from the same place according to the specific similarity of gene sequences. This can help anthropologists track the patterns of migration and settlement, and find out how modern humans formed and developed. In 2002, the Center for Modern Anthropology of Fudan University, the first academic institution in China to study molecular anthropology, was formally established. According to the genetic research and historical migration records of Fudan University, the main reason for the expansion of the Han nationality is the population flow from north to south in history, rather than the so-called southern minorities accepting Chinese culture and forming the southern Han nationality. Nearly 80% of the paternal line of the southern Han nationality comes from the northern Han nationality who moved south from the Central Plains, and nearly 60% of the maternal line comes from the northern Han nationality who moved south. The theory of molecular anthropology is widely used in anthropology and archaeology, and plays an increasingly important role in the origin and evolution of human beings, human migration and communication, the kinship between people, archaeological identification and so on. 1987, the article "Mitochondrial DNA and Human Evolution" by three molecular biologists (R.L. Kan, M. Si Tong King and A.C. Wilson) from the University of California, Berkeley was published in the British magazine Nature. They selected 147 women whose ancestors came from Africa, Europe, Asia, the Middle East, Papua New Guinea and Australia, and successfully extracted mtDNA from the placenta cells of babies after delivery, analyzed its sequence, and drew a phylogenetic tree according to the analysis results. It can be inferred that the measured infant mtDNA can trace all modern people back to a woman who lived in Africa about 290,000 ~10.4 million years ago, with an average of 200,000 years ago. She is the "grandmother" of people living in every corner of the earth today. Then, according to the mutation rate of mtDNA, the approximate time for African population to differentiate into other populations in the world is calculated, which is about 6.5438+0.8 million years to 90,000 years, with an average of about 6.5438+0.3 million years ago. It is believed that about10.3 million years ago, a group of descendants of this "grandmother" left their hometown of Africa, migrated and spread to all parts of the world, gradually replacing the early Homo sapiens, that is, the descendants of indigenous Homo erectus living there, and then settled in all parts of the world, gradually evolving into what we are now. This is the famous "Eve Hypothesis" of the origin of modern people. In 2000, underhill of Stanford University in the United States obtained the 13 1 haplotype composed of 2 18 non-recombination sites on Y chromosome by denaturing high performance liquid chromatography, studied the world's 1062 representative male individuals, and drew the phylogenetic tree according to the analysis results. The results of Y-DNA phylogenetic tree are very similar to those of mtDNA phylogenetic tree. Other modern people in the world, such as Europeans and Asians, originated from Africa, while modern people in the United States and Australia originated from Asians. This is the Adam Hypothesis which is compatible with the Eve Hypothesis. Similarly, according to the mutation rate of Y-DNA, it is estimated that the approximate time for African population to differentiate into other populations in the world is 140000 ~ 40000 years, with an average of about 60000 years ago. 1In July, 1997, the American weekly Science published an article, which caused an uproar in academic circles. M. Krings, a molecular biologist at the University of Munich, Germany, extracted and amplified the mtDNA of Neanderthal fossils about 60,000 years ago. These fossils were discovered in the Neanderthal Canyon in Dü sseldorf, Germany in 1856, and the extracted DNA was sequenced. It is found that there is a 12 fragment in the mtDNA sequence of Nigerians, which is completely different from that of modern people. The mtDNA of Nigerians is outside the variation range of modern people, and the calculated differentiation time is more than 300 thousand years. Historically, Nigerians and modern people have coexisted within 654.38 million+years. If there is a direct genetic relationship between the two races, the difference should not exceed 654.38+ million years. It can be inferred that Nigerians can't be the direct ancestors of modern humans. They didn't pass on their blood to modern humans at all, but just became a sideline in the history of human evolution. This result supports the hypothesis that modern people originated in Africa. This scientific discovery was once rated as one of the top ten scientific and technological achievements in the world from 65438 to 0997. Later, another scientist successfully extracted mtDNA sequences from Neanderthal fossils unearthed in the Caucasus and Croatia, and also concluded that Neanderthals were not related to modern people. Chu Jiayou and others 14 American scholars 1998 published an article in PNAS, which also supported the view that modern people originated in Africa. They used 30 autosomal microsatellite loci (DNA sequences consisting of 2-6 base repeat units) to analyze the genetic structure of 28 East Asian populations, including the Han population in China and the northern and southern populations of ethnic minorities. The research results support the hypothesis that modern China people also originated from Africa. People think that modern China people entered Chinese mainland from Southeast Asia, not from Central Asia. However, due to the small sample size, weak population representation, high mutation rate of microsatellite loci and some limitations in tracing distant events, the work of Chu Jiayou and others cannot convincingly prove that East Asians originated in Africa. 1999, Su Bing and others used a set of Y chromosome haplotypes consisting of 19 Y-SNPs, with a total of 925 individuals, who came from Han and ethnic minorities in China provinces, as well as Northeast Asia, Southeast Asia, Africa, America and Oceania, to systematically study the origin and migration of modern East Asians, including various populations in China. The results showed that all Y-SNP haplotypes in modern East Asian population, including China, came from late mutation, while the early type only existed in Africa. Therefore, people think that all modern East Asians come from an ancient type of Africa. Moreover, East Asians migrated from Southeast Asia to the south of China, then moved northward, and gradually spread to various areas in China and Northeast Asia, which may completely replace the indigenous people who lived there and become new residents in this area. For these modern people who migrated from Africa after a long journey, did they completely replace the original aborigines living on the East Asian continent to become new residents in East Asia, or did they have some degree of integration with the local aborigines, and both of them have made genetic contributions to us now? This problem has also aroused great interest of many scientists. They are based on the assumption that modern people who migrated from Africa did not completely replace the local natives in the group, and the local natives may have a small number of genes inherited. On the basis of the above experiments, they will expand the sample size in East Asia to see the possible contribution rate of these local aborigines or the possibility of incomplete substitution. In which population are these genes likely to remain in modern times? In 200 1 year, Ke Yuehai et al. studied the typing of three Y chromosome haplotypes, M89, M 130 and YAP, on a random sample of nearly 12 000 men in various regions of China. The selected Y chromosome non-recombination region mutants M89, M 130 and YAP are all from another Y chromosome haplotype M 168. The mutation M 168 is a representative mutation site for human beings to go out of Africa and spread to other areas outside Africa. M 168 is the most direct evidence that modern humans originated in Africa alone. Except in Africa, no mutant individuals older than M 168 were found in other regions. The results of this study showed that all the 10,000 samples had one of three mutations, namely M89, M 130 and YAP. No individual was found to carry any type other than the above three Y-SNP mutations, nor were any two or more mutations found in M89, M 130 and YAP at the same time, which was different from other regions of the world except Africa. All 65,438+02,000 samples from China carried the "genetic trace" of the M 168 mutant from Africa. Therefore, the evidence of Y chromosome does not support the hypothesis that modern people in China originated independently, but supports the hypothesis that modern people in East Asia, including China, originated in Africa. Since then, there have been some genetic studies, especially the extensive study of East Asian population by using various genetic markers and typing methods such as Y chromosome, mitochondrial DNA, autosome and single nucleotide polymorphism. The results prove that modern people in East Asia have the same characteristics of African descent. According to the variation rate of Y-DNA haplotypes, it is estimated that about 60,000 ~/kloc-0.8 million years ago, the earliest modern people who left Africa first entered the south of East Asia through Southeast Asia, and gradually spread northward to the East Asian continent with the end of the East Asian Ice Age. The other branch gradually entered the Pacific islands from the Southeast Asian continent along the southeast coast to the east. Haploid genetic points carry two sets of continuous genetic mechanisms. The first group is the inheritance of male Y chromosome passed down from generation to generation. The second set of continuous genetic mechanism is mitochondrial DNA, that is, mtDNA is inherited between women. Only under very special circumstances will mtDNA virus spread among humans. Mitochondrial DNA Mitochondria exist in cytoplasm and are the "energy factories" of cells. They contain a small amount of genetic material-DNA. Everyone's mitochondria come from their mother. Unlike chromosomal DNA as a genome, mitochondrial DNA has the advantage that it will not recombine. If DNA recombination is too frequent, it will lose the ability to trace the paternal origin. On the other hand, mitochondrial DNA constantly clones itself and only accepts little paternal mtDNA. Mitochondrial DNA is not only in a different position from nuclear DNA, but also in a completely different genetic way-it is the only way to trace maternal blood relatives by measuring mitochondrial DNA. Another advantage of mitochondrial DNA lies in the rapid evolution of highly variable regions, which indicates that some chromosome fields of mitochondrial DNA tend to be neutral in the wild. Therefore, mitochondrial DNA is also regarded as a special "clock" to estimate how long ago families separated from each other. Therefore, mitochondria is an important tool to study human evolution from the perspective of maternal inheritance, just as Y chromosome is a tool to study paternal inheritance. At the same time, mitochondrial genome is a genetic material independent of nuclear genome, which is ubiquitous in eukaryotic cells. Mitochondria contain DNA, transcription and translation systems, and are autonomous organelles. Mitochondrial genome has unique advantages: small molecular size and high copy number of mitochondrial DNA; Simple structure and organization, highly conservative; Maternal inheritance, lack of recombination; DNA mutation rate is high. The principle of mitochondrial DNA is the same as that of RFLP, except that the target DNA changes from genomic DNA to mitochondrial DNA. Maternal map Except for male cells, all cells in the human body have mitochondria, but only female mitochondrial genes can be passed on to their offspring with their eggs. MtDNA is the abbreviation of mitochondrial DNA, and it is the substance that carries the mitochondrial genetic code. A man's mitochondria only accompany him all his life, and then end, and cannot be passed on to future generations. MtDNA is maternal inheritance. The structural type of mtDNA is an important index to reflect the maternal situation. By detecting the mtDNA of modern people, we can find out the maternal blood relationship of people in various ethnic groups and places. Through the detection of the mitochondria of ancient corpses, we can find out the matriarchal blood relationship, historical stories, migration routes, nationalities, historical celebrities and so on. Mothers contribute 50% of their genes to their children, and have the same influence on their genetic characteristics as fathers. In ancient times, polygamy sometimes robbed defeated minority women as wives. Because the victors don't adapt to the climate and geographical conditions in the defeated areas, they usually return to their ancestral homes with stolen concubines after the victory of the battle, live with them and have children. Although children born to foreign wives and concubines have half foreign genes, they are culturally regarded as people of the father's nationality. When his son grew up, he continued to rob wives and concubines in foreign countries. His grandchildren are 75% of foreign descent, but they are still regarded as belonging to his grandfather's nation. Although grandson's Y chromosome is still the same as his grandfather's, his mother's mitochondrial mtDNA and body autosome are very different from his grandfather's. This continuous cycle has led to great changes in the bloodline and genes of the national population after several generations, although the national culture and language are still ancestors. Therefore, the structural type and composition ratio of maternal mitochondrial mtDNA in a nation or region can better reflect its genetic and pedigree characteristics than that of paternal Y chromosome. Y chromosome Y chromosome exists in the nucleus, that is, nuclear DNA(nDNA). Unlike mtDNA, the y chromosome is exchanged in the non-recombination region. The essence of a gene is a functional fragment on a DNA chain. It participates in the synthesis of protein and so on, and ultimately determines the characteristics of organisms. Its diversity also determines the diversity of the biological world. In addition, there are more fragments on the DNA chain that have no specific expression function. These fragments are not affected by the pressure of natural selection, and can mutate freely at a uniform speed, which records the history of population evolution more faithfully. Most DNA exists in the nucleus of organisms, and a few DNA molecules exist in other places outside the nucleus, such as mitochondrial memory (mtDNA) in mitochondrial DNA and plant chloroplast memory in chloroplast DNA. In men, the grain * * * is at the tail of * * *. During fertilization, only the head enters the egg, and the tail naturally falls off. Therefore, the child's mtDNA only comes from the mother, showing a way of inheritance with the mother. The most typical representative of paternal inheritance is the Y-DNA in the male nucleus, and the egg has no Y-chromosome. In other words, mtDNA only spreads between mother and daughter, showing strict maternal inheritance; Y-DNA is only passed from father to son, strictly speaking, it is patrilineal inheritance. In the study of molecular anthropology, the study of mtDNA and Y-DNA has great advantages in exploring human history and the origin relationship between different populations: both mtDNA and Y-DNA are haploid and have no recombination, which makes them able to completely preserve the genetic information of maternal or paternal ancestors and easy to construct genealogy trees; The inheritance of mtDNA and Y-DNA is monophyletic, which can directly trace the maternal or paternal genetic history. The sewall wright of mtDNA and Y-DNA is autosomal 1/4. On the one hand, it makes mtDNA and Y-DNA accumulate more mutations in a short time, on the other hand, it is easy to form population-specific genetic markers, thus improving the information and resolution of mtDNA and Y-DNA in evolutionary research. DNA inheritance mitochondria can only be inherited from the mother. In mammals, after fertilization, eggs will destroy mitochondria in * * * *. Studies published in 1999 show that paternal mitochondria (including mtDNA) are labeled by ubiquitin, so they will be selected in embryos and then destroyed. However, some extracellular artificial fertilization techniques can directly inject * * * into egg cells, which may interfere with the process of destroying * * * mitochondria. Because of the characteristics of maternal inheritance, researchers can trace the maternal lineage through mitochondrial DNA (relative to the Y chromosome specially used to trace the paternal lineage), but the characteristics of mitochondrial DNA recombination recently discovered by scientists challenge the concept of mitochondrial Eve. Because mtDNA is not highly conserved, but the mutation rate is very fast, it can be used to study phylogeny. Biologists can select a few genes from different species, analyze the degree of sequence retention and variation, and establish phylogenetic trees. It is assumed that mitochondrial DNA is used to study maternal inheritance, provided that mitochondrial DNA is not easy to recombine and change. However, the theory of molecular anthropology is far from mature, and the application of molecular data to anthropological problems is often proved to be difficult to explain, which is the result of molecular sequence comparison methods. For example, when studying the molecular evolution rate of race A and race B, race C must be chosen as a reference. If the molecular difference between A and C is similar to that of B and C, it is inferred that the molecular velocities of A and B are similar. At the same time, because science depends on future discoveries, it will not conflict with existing theories. In fact, the current findings also have the hypothesis of denying mitochondrial inheritance, so the current theory is likely to be completely denied in the next 20 years. Therefore, we must be cautious about the conclusions of molecular anthropology research and not blindly follow them. Unreliable recombinant scientists believe that mitochondrial DNA molecules are relatively stable and will not exchange DNA fragments with each other. The only factor that causes them to change is spontaneous variation. This change is carried out and accumulated at a relatively stable rate and can be used as a "molecular clock". The difference of mitochondrial DNA between two people determines how many years ago their nearest maternal line lived with their ancestors. Scientists investigated the mitochondrial DNA of women from different regions and nationalities in the world, and determined that the mitochondria of modern people came from a woman about 6.5438+0.5 million years ago. This matriarchal ancestor is called "Mitochondrial Eve". But a few years ago, a rare exception was discovered. Some of a person's mitochondrial DNA comes from his father. In order to test whether the hypothesis that mitochondrial DNA will not recombine is correct, scientists at Harvard Medical School compared the mitochondrial DNA sequence of this man with that of his parents. It was found that some mitochondrial DNA fragments from father were mixed with mother's DNA. Further experiments show that mitochondrial DNA recombination will occur when the enzyme responsible for copying mitochondrial DNA stops copying mother's DNA and jumps on father's DNA to start copying from the corresponding position. This result shows that mitochondrial DNA may not be so stable and will change for reasons other than spontaneous variation. The study of searching for human maternal ancestors is more complicated than people think. However, new research by American scientists also shows that a key scientific hypothesis about mitochondria may be problematic, which makes the "molecular clock" used to trace human maternal ancestors inaccurate. Scientists at Harvard Medical School in the United States said that mtDNA molecules will also undergo DNA fragment exchange and recombination, which is different from what people thought before. This achievement, published in the new issue of American Science magazine, may have an impact on a series of previous scientific research achievements, involving human evolution, primitive human migration, and even the relationship between human languages. According to the study of Han ancestors in 2007, among the residents of Longshan culture in Taosi site in Shaanxi, 100% of the upper nobility is O3, while according to the data of Jinli and AARON Li in 2008, the Y chromosome SNP type of Yangshao culture residents in Shaanxi is O3, so we can clearly see that the ancient Han ancestors, especially the nobles, belong to the residents of Yangshao culture and Longshan culture. O3 is the absolute subject of Han nationality and occupies a very important position. According to the data of Wenbo in 2004, the Han nationality in Shandong is 59.5% (1185), that in Henan is 52%(26/50), that in Shaanxi is 56.7%(5 1/90), and that in Yunnan is 60%. 106), Zhang Yongli was 58.8%(47/80) in Fujian Han nationality in 2002, Hammer's data in 2006 were 65.9%(29/44) in northern Han nationality and 49/84(58.3%) in Taiwan Province Han nationality (note the difference between this data and Zhang Yongli's data in Fujian Han nationality in 2002. 106 O3 was found in 183, accounting for 58.2%, and the data of Minnan Han nationality in Fujian and Taiwan Province Han nationality were highly consistent). According to Xue's data in 2006, the frequency of O3 in Harbin Han population was 68.6%(23/35). In the data of Lu Chuncheng, the Nanjing Han nationality is 53.6% (429/800); In the horse data, Sichuan Han nationality is 61.8% (211/341); The data of Zhou Ruixia in Gansu in 2007 was 7 1.3%. Excluding 83.3% (10/2) of Hebei people, according to the data of AARON Li in 2003, the O3 proportion of Hakka people in Changting, Fujian is as high as 74.3% (1148). There is a similar data, that is, AARON Li's data in the article "The Origin of Liu Jiaren in Guangxi" in 2002 was 77.8%(2 1 person /27 people). Generally speaking, O3 is the main component in all Han people. Different sampling may cause data fluctuation, but the overall frequency is mostly between 50% and 70%. Although it has a vast territory and a large population, it shows amazing consistency within the Han people, showing the homology of the Han people. Today, there are 65.438+0.2 billion Han people, most of whom are direct descendants of the original inhabitants of the Central Plains 5000 years ago. The main body is O3 of Yangshao culture and Longshan culture (the paternal composition of the residents of the two cultures is the same), that is, O3, that is, residents from Yangshao culture and Longshan culture in the Central Plains constitute the vast majority of the paternal ancestors of Han people everywhere, followed by O 1 in magnetic mountain culture, O3, O2 and O 1 in Hongshan Culture, Hebei, and O 1 in Liangzhu culture. Geic evidence of daxi culture in Hubei province and wucheng culture in Jiangxi province supports the demic diffusion of Chinese culture ("genetics proves that the diffusion of China culture originates from population expansion") (Bowen, Hui Li et al., Nature, No.43 1, September 2004, pp.302-305).

Nature in Britain, Science and Cell in America are recognized as the three top academic journals in the world. Based on genetic evidence, this paper demonstrates that the paternal line of the Han nationality in the north and the south is of the same origin, and the spread of Chinese culture stems from population expansion, not so-called "integration" The differences in appearance and physique between the northern and southern Han nationality are mainly caused by maternal differences and geographical environment. According to historical records and archaeological discoveries, the Han nationality in South China originated in the Yellow River Basin and migrated southward from the Yellow River Basin. According to the records of genetic research and historical migration of Fudan University, the main reason for the expansion of the Han nationality is the population flow from north to south in history, rather than the so-called southern minorities accepting the Han culture and forming the southern Han nationality. Nearly 80% of the paternal line of the southern Han nationality comes from the northern Han nationality who moved south from the Central Plains, and nearly 60% of the maternal line comes from the northern Han nationality who moved south. In other words, the main component of the modern southern Han nationality is the northern Han nationality who moved south from the Central Plains, rather than the so-called southern minorities accepting Chinese culture and forming the southern Han nationality.