Dated to around 11,500 BP,[1] Upward Sun River is the site of the oldest human remains discovered on the American side of Beringia.
[7] This individual was given the name Xaasaa Cheege Ts'eniin (Upward Sun River Mouth Child) by the local Healy Lake Tribe[5] and is referred to by archaeologists as USR3.
[2][10] In a 2013 excavation of the site, researchers discovered the remains of two female infants in a layer directly underneath the cremated individual.
[1] The two individuals were covered in red ochre and buried together in a pit burial with grave goods, including four decorated antler rods, two lithic dart points and bifaces.
[16] USR1 shows extra genetic affinity for Siberians and East Asians in a way that is not found in later ancient individuals from the Americas such as Anzick-1, Kennewick Man, or the woman from the Lucy Islands dated to around 6,000 years ago.
[23] This genetic clustering is matched by the archaeological evidence, as the Upward Sun River Site and Trail Creek Cave, despite being located over 750 km (466 mi) away from each other, both share similarities in artefact technology.
[14] Phenotypic analysis shows that USR1 does not carry the derived EDAR allele commonly found in modern East Asians and Native Americans.
[26] Around 300 bone fragments from salmonids were recovered at Upward Sun River, representing the earliest surviving evidence of salmon eating in North America.
[27] An obsidian flake discovered as part of the grave goods found in the infant burial was chemically identified as coming from the Hoodoo Mountain primary source site in Kluane National Park, Yukon, Canada, a location 600 km (370 mi) away from the Upward Sun River site.