DNA evidence has become an invaluable tool for scientists studying the origins and migration patterns of early humans in the Americas. By analyzing DNA extracted from ancient skeletal remains, researchers can trace lineages and connections between populations across continents and thousands of years. But finding well-preserved ancient DNA specimens can be challenging, especially in hot or humid environments where DNA tends to degrade rapidly. So what are the oldest DNA samples found in the Americas, and what secrets have they unlocked about the first people to inhabit these lands?
How old is the oldest human DNA found in the Americas?
The oldest definitive human DNA recovered in the Americas comes from a series of skeletons found at Hoyo Negro, an underwater cave on Mexico’s Yucatán Peninsula. These skeletal remains have been dated to between 10,000 and 13,000 years old. Genetic analysis shows they belong to descendants of Asian populations who migrated across the Bering Land Bridge during the last ice age. This places them among the earliest human inhabitants of the Americas.
Lake Baikal Hunter-Gatherers
The Hoyo Negro individuals show strong genetic similarities to hunter-gatherer populations from Siberia’s Lake Baikal region. In particular, they share ancestry with members of a lineage known as the Ancient North Siberians. This group seems to have diverged from other East Asians around 20,000 years ago and then migrated into North America sometime after 16,000 years ago. Finding this ancient northern genetic signature all the way down in Mexico provides evidence that America’s earliest settlers originated in Siberia.
Beringian Standstill Model
The Lake Baikal connection also supports the “Beringian standstill model,” which proposes thatAsian migrants crossed into Beringia—the land mass that connected Asia and North America during the last ice age—around 25,000 years ago. These pioneer groups were genetically isolated there for up to 15,000 years before rapidly dispersing throughout the Americas about 15,000 years ago. The Hoyo Negro DNA fits as coming from people descended from standstill populations.
Other ancient DNA evidence
While the 10,000 to 13,000 year old Hoyo Negro bones represent the oldest definitively dated human DNA from the Americas, even older genetic material has been recovered. However, the age and origins of these older specimens are more questionable.
Wizards Beach Foot
In 2018, researchers analyzed DNA from a fragmented foot bone found at Wizards Beach, Nevada. They claimed it represented a human that lived in North America over 19,000 years ago. If true, this would push back arrival of humans in North America to before the peak of the last ice age. But there is uncertainty about the accuracy of the dating methods used, so more analysis is needed to confirm the antiquity of this DNA sample.
Alaskan Permafrost
Also in 2018, DNA was recovered from two 40,000 year old teeth found in permafrost deposits in Alaska. If authenticated as human, this DNA would vastly predate any accepted evidence of people in North America. But significant doubts have arisen about the accuracy of the dating methods used, as well as whether the genetic material is actually from Homo sapiens as opposed to extinct Pleistocene mammals. Scientists are actively working to validate these findings.
Oldest South American DNA
When it comes to recoverable ancient DNA, South America seems to lag behind North America. The oldest confirmed human DNA from South America comes from the northern coast of Chile. A skeleton found at the site of Lagoa Santa was radiocarbon dated to 10,960 – 10,250 years old. Its mitochondrial DNA haplogroup matches those widespread among early Central Andean populations.
Even older human DNA has been found at sites like Lauricocha in Peru and Cueva del Milodón in Chile, dating to around 14,000 years ago. However, full genome sequencing has not yet been completed on these specimens to confirm their ancestry and origins. Going forward, ancient DNA from locations like these will help clarify the genetic history of early South Americans.
Old DNA yields new knowledge
While 10,000 years may seem extremely ancient to laypeople, it is quite recent in evolutionary timescales. Recovering and analyzingDNA from skeletal remains over 10,000 years old is a challenging endeavor, but increasingly possible with breakthroughs in extraction techniques and high-throughput sequencing technologies.
Unlocking the genetic code hidden in the bones of the Americas’ earliest inhabitants has profound impact on our understanding of the first chapters of American history. Findings to date have:
- Confirmed the Northeast Asian origins of the earliest Americans
- Supported coastal and inland migration routes south of the ice sheets
- Revealed a 20,000+ year genetic separation between ancestral Native Americans and East Asians
- Linked the earliest Americans to hunter-gatherer populations in Siberia’s Lake Baikal region
Ongoing advances in ancient DNA analysis will provide an increasingly detailed portrait of how and when the Americas were first settled. Exciting findings surely await as scientists refine laboratory and computational techniques for recovering priceless genetic information from the distant past.
Oldest ancient DNA finds in Americas
| Site | Location | Approx. Age |
|---|---|---|
| Hoyo Negro | Mexico | 10,000 – 13,000 years |
| Lagoa Santa | Brazil | 10,000 – 11,000 years |
| Wizard’s Beach | Nevada, USA | 19,000 years (disputed) |
| Alaskan Permafrost | Alaska, USA | 40,000 years (disputed) |
Conclusion
Ancient DNA is rewriting the story of the first Americans. As analysis techniques improve, even older genetic clues will emerge from sites across the Americas. This will provide unprecedented insights into the origins, migrations, and connections of the continent’s earliest inhabitants.