This is the way people come to the new world for the first time … maybe.

About 16000 years ago, when humans approached or reached America through the Bering Strait Continental Bridge, the population surged. Please note that the map indicates the known sites of ancient human remains (red circles) and archaeological sites (black crosses). (? Porter et al., Scientific Citation Index. adv . 20 18； 4:eaat5473) Whether the first people living in America embraced the coast after crossing the Bering Strait or traveled farther inland between two huge ice sheets has puzzled researchers for decades. Now, the examination of archaeological, geological, anthropological and genetic data proves these two views, especially the latter: prehistoric people seem to prefer the inland route, although some people later followed the so-called coastal kelp road trip, a new commentary said.

But not everyone believes this is true. Some recent studies show that the coastline is the preferred route. This is because the inland conditions were too bad before the ice sheet subsided. Some studies show that this did not happen until after the establishment of the first American colony. [Ancient Beasts of the Arctic]

The first Americans started their journey in Northeast Asia and southern Siberia. According to the latest comments, the ancestors of today's Native Americans were separated from East Asians between 25,000 and 20,000 years ago.

What happened next caused a heated debate. It is possible that these people will immediately cross the now submerged Bering Strait Continental Bridge, or they will stay on Bering Island-this concept is called the Bering Island Stagnation Hypothesis. Belingia is a term that describes a huge area, including parts of Russia, and is called Belingia in the west; Alaska, known as Belingia; In the east; And the ancient continental bridge between them.

The commentator has another idea: Maybe this group of people stayed in Northeast Asia, but to some extent, this group of people was genetically isolated from others there. Then, when they cross the land bridge to Alaska, people can go inland most of the time through a new ice-free route. However, scientists have different opinions on when this ice-free route will be opened. )

This map shows archaeological sites 13000 years ago (gray), 10000 to 13000 years ago (white), and geological/biological samples 13300 to 15700 years ago. Please note that the sites in inland areas are usually older than those in coastal areas. (Porter et al., Sci. Ben Potter, head of the department and professor of archaeology at fairbanks University in Alaska, said, April 4th, 20 18: eaat5473, with people approaching or arriving in America, its population surged before 16000. Porter said at a news conference: "The data show that the ancestors of these Native Americans were separated from East Asians for a long time-about 25,000 years ago, they were isolated for a while, genetically isolated." . Later, when these people embarked on their incredible journey, "we saw the evidence of population expansion before16,000 years and before14,000 years, and we saw the earliest clear sites in America."

In addition, there are the oldest archaeological sites from Aleutian Islands to Yakuta Bay (now part of Alaska). The researchers wrote in the comments that this period can be traced back to about 8,000 years ago, more than 6,000 years later than the earliest site in Bering mainland. Researchers say this shows that the first immigrants took the inland route, because the archaeological age of these sites is earlier.

This is the best route. Most archaeologists believe that the ancestors of ancient Greek culture lived in what is now New Mexico from 13000 to 12600 years ago. Archaeologists have long debated this issue. For most of the 20th century, scientists believed that ancient people traveled inland in the North American ice-free corridor between two huge ice sheets. But in the past 20 years, more archaeologists have favored the idea of coastal kelp highway. This is partly because it is not clear whether this ice-free corridor appeared early enough to match the age of known archaeological sites in the United States, and whether this corridor can support a group of migrating humans. [In the photo: the new Clovis site in Sonora]

However, new evidence shows that this ice-free corridor opened earlier than researchers had previously realized. The commentator said that the last degummed part was an unfrozen lake at least 15000 years ago. "Potter said that the plants and animals (large fossils) in this area can be traced back to about 15000 years ago. I want to emphasize that these are the minimum values. This corridor may be more feasible; This is just our first real date. In any case, the assumption that these data use this corridor as a colonial route has once again caused controversy.

Other factors also point to the inland route: these early Americans came from Siberia and Northeast Asia, and all the ancient cultures were inland. They are not on the coast or at sea. "They are hunting mammoths, bison and horses," Potter said. The earliest white people were doing the same thing.

Archaeologists excavated an ancient site in Bering. (Photo credit: Ben A. Potter) Although there are some archaeological sites along the coast of Belinya, the coastal route "KDSPS" is younger than the inland one. The researchers pointed out that supporters of "KDSPS" and "KDSPS" coastal route hypothesis said that many coastal websites do have factors that may be underwater or cannot survive. However, Porter and his colleagues believe that a large area of coastal areas during the Ice Age is still on the water surface, and no coastal sites over12,600 years have been found in the survey, which makes them about 1600 years younger than "the earliest confirmed sites in the interior of Virginia", the researchers wrote in their comments. Therefore, if people walk so far along the coastline, there should be more evidence to survive. However, it is also possible that the population density of today's Native American ancestors is very low, leaving some small sites, which are either not preserved or difficult for archaeologists to find, Justin Tackney said. In addition, in the past 20 years, some archaeologists believe that Clovis was not the first culture in America, but pre-Clovis existed before them, Tackney said. But researchers say Clovis didn't have many sites before. On the contrary, Tackney pointed out that these sites represent "failed migration, which made little genetic or cultural contribution to the later Native Americans", and may also be mistaken for the sites of Clovis' direct ancestors. Tackney told LiveScience: "This review also skipped some websites with unreliable dates.

""This is not a fair comment on literature, and people should be aware of it. However, the researchers did reveal "how the archaeological support of the coastline has weaknesses that need to be explored and explained," he said.

This review was published online in the journal Science Progress yesterday (August 8th).

Early ancient Indian ruins in Belinga, Alaska. Original articles on life sciences