Upward Sun River site facts for kids

The Upward Sun River site, also known as Xaasaa Na’, is an ancient archaeological site. It is located in the Tanana River Valley in Alaska. This site dates back about 11,500 years ago. It is famous for having the oldest human remains found in the American part of Beringia. The site was first discovered in 2006.

The layer at Upward Sun River where human remains were found is very similar to a layer at Ushki Lake in Kamchatka. Both sites are the only ancient burial places found from that time in the Beringia region.

What's in a Name?

The name of the site, Upward Sun River, comes directly from the Middle Tanana language. This is an Athabascan language spoken by local people. The name Xaasaa Na’ was recorded in the 1960s. It came from one of the last speakers of Middle Tanana.

Ancient Human Remains

The first dig at Upward Sun River happened in 2010. During this dig, archaeologists found the cremated remains of a 3-year-old child. This child was cremated inside a fire pit. After the cremation, the pit was filled in, and the site was quickly left empty. The local Healy Lake Tribe named this child Xaasaa Cheege Ts'eniin, which means "Upward Sun River Mouth Child." Scientists call this individual USR3. Sadly, researchers could not get DNA from these remains.

Burial of Two Infants

In 2013, another excavation at the site led to an amazing discovery. Researchers found the remains of two baby girls. They were in a layer right below where the cremated child was found. The two babies were covered in red ochre, a natural pigment. They were buried together in a pit.

They were buried with special items, called grave goods. These included four decorated antler rods and two stone dart points. These items were likely part of a hunting tool system. The local people named the babies Xach'itee'aanenh t'eede gaay (Sunrise child-girl) and Yełkaanenh t'eede gaay (Dawn twilight child-girl). Scientists refer to them as USR1 and USR2.

One baby (USR2) was a fetus, about 30 weeks old, possibly stillborn. The other baby (USR1) was an infant, between 6 and 12 weeks old. The prenatal baby is the youngest Late Pleistocene individual ever found in the Americas. All three children died during the summer months. Their teeth show features similar to those found in Native Americans and people from Northeast Asia.

Studying Ancient DNA

In 2015, scientists were able to get the full mitochondrial DNA from both infant girls. Then, in 2018, they successfully got nuclear DNA from a bone in their skulls. This confirmed that both infants were female, as first thought.

Comparing Ancient DNA

When compared to other ancient people, the DNA of USR1 and USR2 is most like that of Shuká Káa. This individual was found in On Your Knees Cave. USR1 also shows a stronger genetic link to people from Siberia and East Asians. This link is not seen in later ancient people from the Americas.

The DNA of USR1 belongs to a group of people that existed before ancient Native Americans split into northern and southern groups. It doesn't fit neatly into either of those later groups. USR1 forms a unique genetic group with an individual found in Cave 2 of the Trail Creek Caves.

When compared to people living today, USR1's DNA is most similar to modern Native Americans. It is also similar to Siberians and East Asians. However, USR1 does not exactly match any single modern Native American group.

Family Connections

DNA analysis shows that USR1 and USR2 were closely related. They were likely half-siblings or first cousins. However, their mitochondrial DNA shows they did not share the same mother. Both infants carried mitochondrial DNA types found only in the Americas. USR1 had a type called C1b. USR2 had a basic type of Haplogroup B2. This specific B2 type is also found in the individual from Trail Creek Cave. It is different from the B2 type usually found in the Americas.

These discoveries are the northernmost findings of these specific DNA types. They show that the ancient population had more diverse DNA than people today. This supports the idea that people stayed in Beringia for a long time before moving further into the Americas.

The Ancient Beringian People

USR1 is thought to represent a group of ancient people called Ancient Beringian. This group now includes three individuals: USR1, USR2, and a 9,000-year-old individual from Trail Creek Cave. This genetic grouping matches archaeological findings. Even though the Upward Sun River Site and Trail Creek Cave are over 750 km (466 mi) apart, they share similar tool technologies.

Based on USR1's DNA, scientists believe the Ancient Beringians separated from East Asians about 36,000 years ago. There was still some mixing of genes until about 25,000 years ago. The Ancient Beringians are also thought to have separated from the ancestors of Native Americans between 22,000 and 18,100 years ago.

Ancient Salmon Meals

About 300 bone pieces from salmon were found at Upward Sun River. This is the earliest proof of people eating salmon in North America. DNA tests showed the salmon were Oncorhynchus keta, also known as chum salmon. Other tests showed that these salmon swam from the ocean into fresh water to lay eggs.

Other Discoveries

An obsidian flake was found among the items buried with the infants. Obsidian is a type of volcanic glass. Scientists found that this obsidian came from Hoodoo Mountain in Kluane National Park, Canada. This place is about 600 km (370 mi) away from the Upward Sun River site. This shows that these ancient people traveled far or traded with other groups.

See also

In Spanish: Upward Sun River para niños