Researchers have managed to sequence the genome of an ancient child that was descended from one of the original founding humans to have stepped foot in the Americas.
The genome of this ancient Alaskan child provides the first direct genetic evidence that all Native Americans can be traced back to one population that lived in the Beringia region at least 11,500 years ago. The DNA preserved in the remains shows that the infant – along with the ancestors of other Native Americans – was descended from a single founding population of humans who likely populated the Beringia land bridge some 36,000 years ago.
This, the authors note, does not mean that there was no further genetic flow from East Asia, which likely occurred as humans continued to cross over into Alaska until around 25,000 years ago. However, it does suggest that the ancient human remains likely represent a distinct population now known as the “Ancient Beringians”. The DNA of these Ancient Beringians is closer to that of ancient and modern Native Americans than it is to East Asians, suggesting that they were indeed the original founding population, according to the paper published in Nature.
The history of ancient humans in the Americas has always been somewhat obscure. Obviously, Native Americans have been present in the continent for thousands of years, and genetic evidence shows that they likely descended from humans who once lived in Eastern Asia and Siberia around 20-30,000 years ago. But there is scant physical evidence to support many of these theories, and the archaeological evidence that does exist is often confusing.
For example, there are sites dated to around 13,000 years old in the north east of the Americas where many think the first humans to populate the continent would have first occurred, but there are also sites dating to around 15,000 years old in South America, thousands of kilometers away. This has tended to confuse the picture of human migration.
The most commonly accepted theory is that the peopling of America occurred during the Pleistocene, when the sea levels were lower and the Beringia land bridge connected Asia and North America. It is generally thought that by 11,000 years ago, after the Last Glacial Maximum, the land bridge was once again submerged and the two landmasses were separated.
The genetic evidence now retrieved from Alaska backs this up, implying that when Beringia was still high and dry, a population of ancient humans originally from Siberia moved into the land. These people then became largely genetically isolated as the Ancient Beringians, before then moving across the bridge into the Americas. The land bridge then sank beneath the waves and the first Americans were cut off, though perhaps other peoples may occasionally have turned up by boat.
