Researchers Decode Secrets Surrounding Human DNA
In the 1860s, Swiss chemist Friedrich Miescher discovered human DNA, a breakthrough that helped scientists unravel the mysteries of our ancestors. Even in 2018, there are still numerous new discoveries being made. Today, we will delve into ancient secrets that pertain to an unknown group of ancestors.
Two 11,500-Year-Old Skeletons Unearthed
In 2018, archaeologists unearthed two skeletons of Native Americans during an excavation. Both skeletons appeared to be around 11,500 years old and were from the same family. However, this was not an ordinary find.
The skeletons were remarkably well-preserved, allowing scientists to uncover new information. In fact, this discovery provided insights into the first-ever humans to have lived in North America.
Researchers Journeyed to Alaska
In the early 2000s, anthropology professor Ben Potter was working in Upward Sun River, Alaska. It is a densely forested area located 50 miles from Fairbanks, accessible only by helicopter.
Despite the challenging conditions, Potter had a good reason to travel there. This part of Alaska was once connected to Europe and Africa, and he was confident that he could unveil some secrets hidden within.
What is Beringia?
When Pangea split apart, there were land bridges that connected different continents. The earliest known humans originated from Africa and migrated across the world.
Beringia was the land bridge that connected Siberia and Alaska. Many archaeologists believe that the first humans arrived in North America by crossing this bridge approximately 34,000 years ago. However, this remains just a theory—the Beringia Standstill Hypothesis.
While many historians believe that people crossed Beringia, it is challenging to identify who these individuals were exactly. Within the "Beringia Standstill" hypothesis, it is explained that the "Native Beringians" lived on Beringia in isolation due to the ice and harsh climate. If true, the Beringians could be the sole ancestors of Native Americans, as suggested by archaeologist Jennifer Raff.
Native Americans Still Thriving in Upward Sun River
The name "Upward Sun River" is the Athabascan translation of "Xaasaa Na," the language of Native Americans who still reside in Alaska to this day. The region belongs to their territory.
Potter collaborated with the indigenous people during the excavations. Normally, they are protective of burial sites, but they recognized the importance of Potter's work in uncovering their past.
The First Discovery – Three-Year-Old Child
In 2010, Potter and other researchers from the University of Alaska began investigating Upward Sun River further. They discovered the cremated remains of a three-year-old child.
The findings suggested that these remains dated back 11,500 years, making it an extraordinary discovery. Unfortunately, the skeleton was not well-preserved enough for DNA analysis, and the gender of the child remained unconfirmed.
Potter's Perseverance
Despite limited success, Potter and his team refused to give up. They continued their excavations in the area for another eight years. Then, they had a major breakthrough, thanks to Potter and his colleagues José Moreno Mayar and Lasse Vinner. They found another burial site in the same Alaska region that appeared to be around 15,000 years old.
This time, Potter and his team unearthed two skeletons of newborn infants. One appeared to be stillborn, while the other was between six and twelve weeks old. Similar to the previously discovered three-year-old child, these infants had been cremated, with their remains found within a hearth. However, this time, the find was better preserved.
The two newborns were buried beneath several objects and covered in red ochre. This ochre played a crucial role in preserving the skeletons so well.
The babies were buried in a mixture of sand and soil, which had a high acid content, providing the perfect conditions for preservation. Whoever buried them had put in considerable effort.
Who were the Two Girls?DNA tests revealed that both newborns were female and were likely cousins. The stillborn child was approximately 30 weeks old and had no chance of survival.
The local indigenous community finally gave the girls names: "Xach’itee’aanenh T’eede Gaay," meaning Sunrise Girl-Child, and "Yelkaanenh T’eede Gaay," meaning Dawn Girl-Child.
Other Objects in the BurialThis burial site held significant meaning for the grieving community. Archaeologists uncovered numerous objects within the grave, such as antlers and spear points. Both girls were buried together, but the six-week-old infant was better preserved.
To decode the DNA, researchers needed to examine the intact cells' mitochondria more closely. For those who remember their biology lessons, mitochondria are the "powerhouses" of cells. However, this task was easier said than done.
Results of the DNA TestsThe first round of DNA testing took place at the University of Alaska, revealing the Sunrise Girl's ethnicity. According to the results, she was closely related to Native Americans.
Scientists believe that the DNA is much older than any previously discovered remains, suggesting that the girl belongs to a previously unknown genetic group of Native Americans.
New-Old PeopleThis previously unknown DNA, referred to as "USR1" by scientists, could be between 20,000 and 34,000 years old.
Eske Willerslev, co-author of the study and professor at the University of Copenhagen, stated, "This discovery changes our understanding of the timing of events that led to the genetics of Native Americans," according to CNN Health.
They Could Be Ancient BeringiansThe Sunrise Girl's DNA supports the Beringian Standstill hypothesis. Scientists believe she belonged to an ancient Beringian population, which had previously only been discussed in theory.
"We think the explanation for this pattern that requires the least movement is that there were Indians living in Beringia 20,000 years ago," explained Victor Moreno Mayar, another author of the study.
Two Girls with Different DNAThe first DNA analysis was conducted on the skull of the six-week-old infant. Genetic experts expected similar DNA in the second newborn, but surprisingly, they were mistaken.
The stillborn girl was examined at the University of Copenhagen, Denmark. She had a completely different maternal lineage from her first-degree cousin, with a completely different genetic origin.
Different Branches of AncestryAccording to current assumptions, genetics divide Native Americans into two branches: northern and southern Native Americans. The northern group originated from East Asia and settled in North America, including Alaska and Canada.
At some point, the group split, with some migrating southwards. All of them seem to descend from the Beringians. However, as they separated, there was variation in their original DNA.
In simple terms, the DNA tests indicated that the girls belonged to two different groups. The Sunrise Girl belonged to the Beringian indigenous group, while the Dawn Girl had a closer genetic connection to the northern
Native Americans. So the big question remains: how did these two groups meet at the same place and time?
Sunrise Girl Belonged to a Mysterious Third GroupSurprisingly, the Sunrise Girl did not fit into the categories of either North or South America, suggesting that the Beringian indigenous population may have divided into three or more groups.
Using demographic models, scientists attempted to reconstruct how the Native Americans left East Asia over 36,000 years ago. The group must have divided around 20,000 years ago. But then how was it possible for the two girls to be buried together?
All Groups Stem from a ClanThe study proposes the hypothesis that the two groups encountered each other after their initial separation, explaining why the girls were related. There are two possibilities for this theory.
The Beringians may have separated before crossing the land bridge, only to meet again later. Alternatively, the Beringians could have split at a later stage. Potter favored the latter option.
Separation before BeringiaPotter put forth a concrete theory on how the two groups met. During an interview with The Atlantic, he suggested that both groups might have crossed Beringia separately, possibly choosing different routes. This theory is supported by evidence.
In 2017, archaeologists explored the Bluefish Caves in Canada's Yukon Territory. They found human cut marks that seemed to date back 24,000 years. Therefore, Raff believes that humans crossed Beringia at least 24,000 years ago.
Unanswered QuestionsWhile the discovery of this burial site supported many hypotheses, it also raises further questions. What happened to the Beringians? How did they initially make their way to Siberia?
Considering how rare such discoveries are, it is unlikely that these questions will be answered soon. To make matters more complicated, not all experts agree with Potter's theory.
Experts Counter Potter's AssumptionsThe main argument against the findings is that it is a single discovery! Dennis O'Rourke, a geneticist and archaeologist, argues that a single find does not provide enough evidence to study the entire human evolutionary history.
"We might learn something about the diversity of the Beringian population, but multiple genomes would provide more probability," O'Rourke said to The Smithsonian Magazine.
Rare FindsDiscovering more than a single find is easier said than done. "It's hard to put into words how rare a find like this is," said Potter to The Atlantic.
According to co-researcher Willerslev, prior to this discovery, scientists only had modern Alaskan inhabitants and Siberians to study this genome. Without further samples, no one will know where the Beringians came from.
Upward River Is Too Recent for Indigenous PeopleDespite the age of the Upward River burial site, archaeologist Brian T. Wygal believes that the region is too recent to truly understand the indigenous people.
"The earliest documented evidence of human activity in eastern Beringia was about 14,100 years ago," Wygal explained. "It seems that Upward Sun River is about 3,000 years too young to be representative of the original colonization of people."
What Happened to the Beringians?After Potter's study was published in the scientific journal Nature, many people wondered what happened to the Beringians. "We don't know," said Potter to CNN.
The question simply requires more evidence to be answered. Potter plans to take additional DNA samples from residents of the surrounding regions. Now that the Beringian DNA has been identified, it can be determined if these genes still exist today.
Researchers have now provided a first glimpse into the lives of the Beringians. According to Potter, they were skilled hunters, relying on bison, moose, rabbits, squirrels, and birds for sustenance. They likely had well-organized hunting strategies and hunted in groups. Potter also found evidence of salmon fishing dating back 6,000 years, suggesting that the Beringians engaged in fishing and trade.
Potter further pointed out that Beringian genes resembled those of Alaska's Native Americans. This is a natural consequence of evolution. "It is possible that incoming ancient Athabaskan ancestors, who are widespread in the region today and occupied this area, replaced or absorbed" the Beringians, claimed Potter. If this is true, many people may have Beringian blood without even knowing it.