A grave beneath the hearth
In 2013, at an archaeological site in Alaska's Tanana River Valley known as Upward Sun River, researchers uncovered a burial pit dated to 11,500 years ago. The discovery was made directly beneath a hearth where, in a previous excavation in 2010, the cremated remains of a three-year-old child had been found. Inside this lower pit lay two more individuals: a 6-to-12-week-old infant (designated USR1) and a prenatal fetus of about 30 weeks (USR2).
The two infants were buried with care. Their remains were covered in red ochre, a pigment frequently used in ancient burials. Accompanying them were grave goods, including four antler rods decorated with incised lines and two stone projectile points. These artifacts likely formed parts of a weapon system, such as darts or spears, and suggest a ritualistic interment. The local Healy Lake Tribe named the infants Xach'itee'aanenh T'eede Gaay ("sunrise girl-child") and Yełkaanenh T'eede Gaay ("dawn twilight girl-child").
The site was not a cemetery but a seasonal residential camp. Faunal remains indicate that its inhabitants had a varied diet that included salmon, ground squirrels, and birds. The discovery of these burials shows the social customs and mortuary practices of people living at the end of the last Ice Age.
A new branch on the human family tree
While the archaeological context was significant, the surprising discovery came from the lab. Scientists successfully sequenced the complete nuclear genome from the remains of USR1, "sunrise girl-child". The results, published in the journal Nature in 2018, did not match any known Native American lineage.
Before this study, ancestral Native Americans were understood to have split into two branches—Northern and Southern. The genome of USR1 belonged to neither. Instead, it represented an entirely new, genetically distinct population that scientists named "Ancient Beringians". Genetic modeling shows this group diverged from the ancestors of all other Native Americans around 20,000 years ago.
This discovery changed the history of the peopling of the Americas. It suggests a single founding population migrated from Asia. This group then divided, with the ancestors of all other Native Americans moving south to populate the continents. The Ancient Beringians, however, remained in the far north. They are a ghost lineage—a population whose existence is known only through ancient DNA, as they appear to have left no living descendants. What Happened to them is unknown; they may have been absorbed by later migrating groups or simply died out.