Genetics has rewritten the history of early America, and perhaps the field of archaeology.

The story about how Homo sapiens spread from Africa to other parts of the world is a complicated epic full of false beginnings and dead ends. However, perhaps nowhere is it more difficult than America. Two continents are separated from the rest of the world by two huge oceans. However, narrowing down the scope, you will find that this isolation has only been implemented in the past 11, years; Before that, a narrow land bridge named Beringia extended between Siberia and Alaska, providing travelers with an icy road. Humans may have arrived in North America 1 years earlier than we thought this week, 1 years earlier. Scientists reported an explosive new discovery about the genetic story of ancient travelers: local aborigines gave it to a baby girl named Xach 'itee 'aanheh t 'eedegaay, who lived for a short time in a community in Alaska 11,5 years ago and is now called the upper reaches of the Sun River. Baby's genome has the ability to rewrite our understanding of human's journey into North America, and point out that it is reshaping the greater genetic revolution in the field of archaeology.

For decades, archaeologists have assumed that humans entered America from Asia using Beringia. The person who thinks there is a land bridge is actually a Spanish missionary Frey Jose de acosta in the 16th century. But even if more occupation points are found in Siberia and Alaska, pointing out human occupation and movement from west to east, the problem still exists. When and how did immigration happen? In one or more waves? In January, 217, researchers from the Canadian Museum of History concluded that a horse jaw found in the Blue Fish Cave in Yukon had a human mark of 24, years ago, which means that early Americans had settled here in 22, BC. This will delay the date of human occupation in North America by 1, years. However, these findings are controversial in this field and have not been generally accepted by the archaeological community.

The new report on Xach' itee' aanheh t' eedegaay makes this statement more complicated. Although she may be "only" 115 years old, she provides indisputable evidence for the time of human migration.

In her genome is the story of a newly discovered early American group. Their ultimate fate is still a mystery, because their genes are no longer visible in modern people. Eske Willerslev, an evolutionary geneticist and one of the authors of this new study, said: "This individual represents a previously unknown population, which is also the earliest known population of Native Americans." . "We can solve some basic problems, such as when people will come to North America, because this population is related to others."

The upward Sun River girl was buried next to an even younger baby, both of whom were in the red ochre ritual grave, and she was a member of what researchers called the ancient white people. Before sequencing her genome, scientists had identified two main groups of Native Americans: North American Native Americans and South American Native Americans, who split up at some point after entering the American continent. The baby does not belong to these two groups. This means that somewhere in this process, another division must have taken place, creating this unique ancient Bering language group.

Through demographic modeling, the researchers concluded that the founders of Native Americans began to separate from their ancestors in East Asia about 36, years ago. By 25, years ago, they were completely divided. By 2, years ago, there was another disagreement, this time between the ancient Berliners and other Native Americans. In the next 3, to 6, years, Native Americans were further divided into two groups, the North and the South.

all these things come from the ancient DNA of a long-dead child. I watched Ben Porter and Josh Luther, professors of the University of Alaska at fairbanks, dig at the site in the upper reaches of the Sun River. Victor Moreno Mayar, another author of the paper and a geneticist at the Center for Geogenetics, said: "Now we have these restrictions on the formation of Native Americans." . "We think the explanation for this model is that Native Americans were somewhere in Bering 2, years ago. The most supported archaeological site in Alaska is only 15, years old, so we have pushed back the time, so it will be controversial.

The author is well aware that this research may be controversial. To this end, they included two different models to explain how the ancient white people came into being. In one version, Bai Ren was separated from other Native Americans before crossing the continental bridge into North America, which meant multiple waves of immigration. In the second group, this group crossed Bering as a group, but it was later split. One of the authors, archaeologist Ben Potter, supports the former.

"I tend to support this point in archaeology, because it accords with most archaeological evidence we have," said Porter, who has been working at the site of the upper reaches of the Sun River since 26 and discovered these children in 213. "This is not only the lack of sites (in Bering and North America), but also a powerful site data set, which shows that from Northeast Asia to Aldan, to Northeast Siberia, and finally to Bering at the age of 14, 5.

, but how can two different scientific explanations exist? Welcome to the real struggle of human history stories: whose fact comes first, the fact of archaeologists or the fact of geneticists. As Porter said, genetics provides information about population and its division, while archaeology points out the physical location of these populations and their interaction with the environment. Scientists find that they must combine these two pieces of information in a way that seems not always consistent.

"We should remember that the earliest confirmed traces of human activities in the eastern part of Bering Island can be traced back to about 14.1 thousand years ago, which makes the ruins of the Sun River upward too young for nearly 3, years," becoming the representative of the first human colony in the New World, "Brian T. Waigal, an archaeologist at Adelphi University, said by email. "According to archaeological data alone, by the time we reached the children's tombs in the upper reaches of the Sun River, the variability of human beings in the late Pleistocene was quite large."

Dennis Oruk, a geneticist and archaeologist at the University of Kansas, sequenced the mitochondrial DNA of infants in the upper reaches of the Sun River in his laboratory a few years ago, but did not participate in this research. Oruk also believes that with the increasingly complex archaeology and genetics, there are some growing problems in this field.

"How to integrate these different types of data and approaches to the past is a constant challenge," Oruk said. "This paper raises some questions. Archaeological and genetic data may point to different geographical populations, but I think these problems will eventually be solved by more archaeological and genomic data from different geographical regions.

this is not the first time that such a question has been raised. As Nicola Di Co *** a, an East Asian historian, wrote for the Institute of Advanced Study, "In ancient DNA research, it is quite common to explain the trend of gene distribution according to the assumed behavior patterns of some ethnic groups and societies. In the final analysis, these assumptions can be traced back to historical, anthropological and archaeological models, and sometimes they are not the best models. "This leads to another problem of this new study: it relies on a single sample. "If we have more than one genome, we can know more exactly the diversity of early Bering population," O'Rourke said.

Di-Co *** a is more straightforward. "There are very few samples from which ancient DNA information is extracted: how much do they have to do with the population movement in Eurasia for thousands of years? He wrote:

, but ancient remains are extremely rare, and even if they are found, using them in scientific research is full of ethical problems. Perhaps the most famous is Kennewick, a 9-year-old man who was found in Washington. He triggered a legal dispute between scientists and local indigenous groups, who wanted to rebury him. Willers Lev finally proved the genetic connection between ancient bones and modern Native Americans with DNA samples, allowing him to be repatriated according to the Native American Grave Protection and Repatriation Act.

Porter and other team members try to avoid any mistakes in analyzing the upward Sun River children, and cooperate with local tribes before doing any tests and trying to answer questions they may be interested in. Smithsonian. contacted Tanana Chiefs' Meeting, a federation of 42 member tribes in Alaska, including the area where the upper reaches of the Sun River are located, but did not get any response before publication.

the team's analysis has found fascinating insights. For example, Porter said that the discovery from the rising sun "represents the first evidence that humans use salmon in the new world". "One of the factors that we can develop through bones is that we want to observe the mother's diet and possible changes over time, which may let us know whether people store salmon in winter."

Finally, Oruk said that the most valuable knowledge from this discovery and future discoveries may be some combination of genetics, artifacts and paleoenvironmental data. Taken together, the integration of science can show how human beings create material culture to interact with the environment and survive in it.

"We always go further in one place than in another," Oruk said. "This is the challenge of how to integrate these different knowledge streams."

Editor's Note, January 5, 218: This article has been updated to clarify how the new paper presents different models of the origin of ancient Bai people.