A few years ago the fossilized remains of a baby girl were uncovered in a harsh and isolated part of central Alaska. The remains were dated at 11,500 years old, and a new DNA study has now revealed not only an incredible insight into the origins of human migration into North America, but also the existence of a previously undiscovered population of humans that have been named "Ancient Beringians".

The conventional theory about how humans migrated into the Americas suggests that sometime between 15,000 and 30,000 years ago, humans wandered from Asia into North America across a land bridge called Beringia that connected the two continents.

This latest discovery reveals a distinctive, and previously undiscovered human lineage that surprised researchers, who were expecting to find a genetic profile that matched northern Native American people. The study of this ancient child's DNA pointed to an entirely new population of people, separate to those that ultimately spread throughout the rest of North America.

The researchers suggest two possible theories to explain this new lineage. Either two separate groups of people crossed the land bridge into the Americas over 15,000 years ago, or one group crossed, and then split into two entirely independent populations. Closer genetic sequencing suggests the latter outcome is the most likely, but why and how this Ancient Beringian population remained so genetically isolated and distinct for so many subsequent years remains a mystery.

The study also posits that a type of "back migration" occurred, possibly around 6,000 years ago, as northern Native American populations spread back up into Alaska and either absorbed or replaced the Beringian population, resulting in a distinct Alaskan native population called the Athabascan.

"There is very limited genetic information about modern Alaska Athabascan people," says Ben Potter, one of the lead authors on the study. "These findings create opportunities for Alaska Native people to gain new knowledge about their own connections to both the northern Native American and Ancient Beringian people."

The new study was published in the journal Nature.

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