6,000-year-old skeletons found in Colombia have unique DNA

Scientists studying ancient human remains uncovered in Colombia have found that the people they were researching have no known ancestors or modern descendants.
In a study published May 30 in the journal Science Advances, a team of researchers reported on the genetic data of 21 individuals whose skeletal remains were found in the Bogotá Altiplano in central Colombia, some of whom lived as long as 6,000 years ago, that belonged to a previously unknown population.
Previous studies have proven the existence of two lineages, northern Native American and southern Native American, which developed after people first arrived on the continent across an ice bridge from Siberia and started to move south.
The latter split into at least three sub-lineages whose movements have been traced in South America, but scientists have not yet ascertained when the first people would have moved from Central America to South America.
The study helps to map the movements of the first settlers, who would have been nomadic hunter-gatherers, study author Andrea Casas Vargas, a researcher at the Universidad Nacional de Colombia, told CNN on Wednesday, but it also found that they have unique DNA.
Casas Vargas said the team were 'very surprised' to find that the remains did not share DNA with other people in the genetic record.
'We did not expect to find a lineage that had not been reported in other populations,' she said.
Casas Vargas underlined that Colombia's position as the entry point to South America makes it significant to our understanding of the population of the Americas.
'This study is very important because it is the first to sequence complete genomes in ancient samples from Colombia,' she said,
The results raise questions 'as to where they came from and why they disappeared,' said Casas Vargas.
'We are not certain what happened at that time that caused their disappearance, whether it was due to environmental changes, or if they were replaced by other population groups,' she added.
Further research will hopefully provide some answers, said Casas Vargas.
'Our next investigations will look for other archaeological remains from other regions of the country and analyze them at the genetic level and complement this first discovery,' she said.
Christina Warinner, a professor of scientific archaeology at Harvard University, told CNN that Colombia 'is a key region for understanding the peopling of South America… but until now it has been a blank spot in ancient DNA studies of the Americas.'
'This study highlights the deep history of population migration and mixing in the formation today's populations, and points to Central America as a key region that influenced the development of complex societies in both North and South America,' she added.

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