Human Migration Trajectory Hidden In Ancient DNA

Zheng Lei / Wen

After 2009, the research on the whole genome DNA of ancient human beings began to challenge the habits of archaeology, anthropology and even linguistics. Professor David Reich is the pioneer of this field. His story of the origin of mankind provides readers with a clear picture of where the ancestors of all continents came from from the perspective of ancient DNA. From this we can understand how different ethnic groups integrate, replace and expand, and the relationship between the human family.

The story of the origin of mankind. Data map

Since the beginning of 2001, the cost of genome sequencing has dropped dramatically, and people have started to directly compare the whole genome information and reconstruct thousands of genetic paths for each person. It is found that a great number of ancestral information can be excavated from a human genome. Each person carries 2 genomes, each from the father and mother. By calculating the density difference between these two genomes, we can infer the existence time of common ancestor in different locations on two genomes (Li Heng, Richard Durbin, 2011), which laid the theoretical foundation for the study of ancient DNA.

The expansion of modern humans was not more than 50 thousand years ago. About 40 thousand years ago, the world still lived in other ancient human groups that walked upright and possessed some modern abilities, but modern humans eventually eliminated other subspecies. Genetic studies showed that some of the subspecies of ancient humans disappeared, but their genes left traces. For example, the earliest Neanderthal population in Europe is partly due to the small population and the mixed race with larger populations, which may lead to a decline in fertility. Among the populations outside Africa, the genes from Neanderthal people account for 1.5%-2.1%, and East Asian people are more than Europeans.

All modern people have migrated from Africa and the Middle East to other regions 50 thousand years ago, but they may have crossed the original races. An important achievement of the whole genome of ancient DNA is to explain the path of global human migration. According to the existing research results, we know that humans have walked out of Africa for at least two times. For the first time, they have gone through the near east to Europe, northern Asia and southern Asia, forming ancient Europeans, northern Eurasia and ancient East Asians. At that time, people in northern Eurasia who lived in Siberia used to have the Bering land bridge to the Americas. The Aboriginal people in the Americas inherited some 1/3 from ancient North Eurasia. Human beings outside Africa are basically the result of the integration of large groups of people.

During the last ice age (25000-19000 years ago), glaciers covered the northern and mid latitudes of Europe, where primitive humans fled to southern Europe. 14000 years ago, the earth's climate warming, once extended to the Mediterranean, near the nice Alpine glacier wall melting, so southeast Europe's population and animals and plants flowed into the north and southwest, sweeping across the continent. 12000-11000 years ago, agriculture originated in southeastern Turkey and Northern Syria, and hunter gatherers began to domesticate animals and plants. After that, these groups spread and fused with the agricultural civilization. About 9000 years ago, agriculture began to spread to Greece, India and Pakistan, and spread to Europe, Britain, Germany and the Scandinavia Peninsula in Europe. Domestication technology is a major technological development, facilitating further integration of human beings and narrowing the genetic gap between Eurasian and African populations. For example, Turkey farmers entered Europe, Israel and Jordanian people entered Africa, a group of people entered India and the prairie of Central Asia, intermarriage and the establishment of a new economy based on animal husbandry, and promoted the spread of agricultural revolution to the rest of the world. 5000 years ago, technological progress in the Bronze Age accelerated this process. In the history of modern Europeans, there was a fusion of human migration from the Eurasian steppe 5000 years ago, and the Indo European language family was formed.

The author also pointed out that more than 16000 years ago, North America was covered by ice sheets, and there was no ice on the east coast of the Pacific. The first Asian people had migrated to the Americas through the Bering land bridge along the coast. About 13000 years ago, an ice free corridor formed in the middle of the North American ice sheet, and another wave moved south.

In East Asia, mankind has existed for more than 1 million 700 thousand years, and it was an agricultural independent place in the Near East about 9000 years ago, and then integrated into agriculture in the Near East in India. The ancestors of Southeast Asia and Taiwan came from an ancestral group in the Yangtze River Valley, but a large part of the Han population came from the East Asian branch. A large proportion of the Han and Tibetan populations came from the same group of ancestors in the the Yellow River River Basin. These two groups are different in the Yellow River and Yangtze River Basin respectively. In recent 2000, there was an epic migration expansion and large-scale mixed race in China. We really want to know the relationship between the ancestors of East Asian people and the migration history of East Asian population after the last ice age. China has now set up a world-class DNA laboratory, and believes that the day for revealing the answer is not far away.