Wednesday , January 27 2021

Who were the first Americans? 11,000 years old old DNA reveals clues



People genetically linked to the Clovis culture, one of the oldest continental cultures in North America, made it to South America just 11,000 years ago. Then they mysteriously disappeared about 9,000 years ago, new research shows.

Where did they go? It seems that another group of old people has replaced them, but it is not clear how and why this happened, the researchers said.

These findings, published online today (November 8th) in Cell magazine, suggest that this population evolution took place across the continent of South America. [In Photos: Human Skeleton Sheds Light on First Americans]

Previous studies suggest that the first Americans genetically separated from their ancestors from Siberia and East Asia almost 25,000 years ago. These people traveled to the Bering Strait land bridge and eventually were divided into distinct populations in northern and southern America. About 13,000 years ago, Clovis cultured people, known for using distinct stone tools, entered North America. Meanwhile, people lived south of Monte Verde, Chile, at least 14,500 years ago, according to the archaeological finds there.

But little was known about how members of the Clovis culture were linked to other southern populations.

Excavation in 2014 at the rock shelter of Lapa do Santo, Brazil, where a person dated 9 600 years ago was found.

Excavation in 2014 at the rock shelter of Lapa do Santo, Brazil, where a person dated 9 600 years ago was found.

Faith: André Strauss

To reveal the genetic mysteries of these ancient Americans, the researchers turned to indigenous peoples and government agencies throughout Central and South America, asking for permission to study the remains of ancient peoples that have been discovered over the years.

In total, the international team of scientists received permission to perform genomic analysis on 49 old people whose remains were found in the following countries in Central and South America: Belize, Brazil, Peru, Chile and Argentina. The oldest of these people lived about 11,000 years ago, marking this as a study that makes a big step forward from previous research that included only genetic data from individuals less than 1,000 years old, they said researchers.

Their findings have shown that DNA associated with North American Clovis culture is found in people from Chile, Brazil and Belize, but only between about 11,000 and 9,000 years ago.

"A key discovery was that an individual associated with Clovis culture in North America, dating back to 12,800 years, shares distinguished ancestors with the oldest Chilean, Brazilian and Belizean individuals," co-lead author Cosimo Posth, a researcher postdoctoral archeogenetics at the Max Planck Institute for the History of Human History in Germany, said in a statement. "This supports the hypothesis that the expansion of people who have spread Clovis culture to North America has also reached Central and South America." [In Photos: New Clovis Site in Sonora]

Exterior view of Lapa do Santo in Brazil

Exterior view of Lapa do Santo in Brazil

Faith: André Strauss

Curiously, about 9,000 years ago, the Clovis family disappeared, researchers found. Even today, there is no DNA associated with Clovis found in modern South Americans, the researchers said. This suggests that a continentwide population change occurred at that time, "said co-researcher researcher David Reich, professor of genetics at Harvard Medical School and an investigator Howard Hughes Medical Institute.

As a result of this mysterious disappearance, there is a surprising source of genetic continuity between people who lived 9,000 years ago and those who live today in several regions of South America, the researchers said.

The Cell study also revealed a surprising connection between the old people living in the Canal Islands in California and the Peruvian years in the South at least 4,200 years ago. It seems that these two distant geographic groups have a common relative, the researchers found.

It is unlikely that people living in the Canal Islands actually travel south to Peru, the researchers said. Rather, it is possible that the ancestors of these groups rescued thousands of years earlier, some reaching the Channel Islands and others in South America. But these genes have not become commonplace in Peru until much later, about 4,200 years ago when the population exploded, scientists said. [In Photos: 130,000-Year-Old Evidence of Humans in California]

"It could be that this ancestry arrived in South America thousands of years ago and we simply do not have any previous individuals to show them," said co-pilot of Nathan Nakatsuka, a research assistant in the Reich lab from Harvard Medical School. the statement. "There is archeological evidence that the people of the Central Andes have expanded a lot about 5000 years ago. Spreads of certain subgroups during these events may be the reason why we will discover this ancestor afterwards."

The person about 11,000 years old from the Los Rieles site in Chile was the oldest in the study.

The person about 11,000 years old from the Los Rieles site in Chile was the oldest in the study.

Credit: Bernardita Ladrón de Guevara, 2008

Though these findings cast a light on the early Americans, it is far from complete. Researchers admit that they do not have human remains older than 11,000 years old and so we were unable to directly investigate people's initial movements in Central and South America, "they wrote in the study. people who lived between 11,000 and 3,000 years ago, research would be more comprehensive if more ancient individuals from different regions were included, the researchers said.

"We did not have ancient data from the Amazon, North America and the Caribbean, so we can not determine how individuals in these regions refer to those we analyzed," Reich said in the statement. "Filling these gaps should be a priority for future work."

Originally published on living science.


Source link