Native Americans have a complex genetic history shaped by population bottlenecks, geographic isolation, and mixing between diverse source populations. Analyzing the genetic makeup of modern Native Americans can provide insights into their origins and history.
Quick Answers
In brief, modern Native Americans descend primarily from ancient East Asians who crossed into the Americas via Beringia. However, there was significant mixing with other groups after the initial settlement of the Americas:
- Most North American tribes mixed extensively with Europeans after contact, especially British and French settlers.
- Some East Coast tribes mixed with Vikings around 1000 CE.
- Inuit and Aleut mixed with Russian explorers and traders.
- Native Americans in Mexico and Central/South America mixed with Spaniards.
- Some tribes along the Atlantic coast intermarried with African slaves during colonial times.
Additionally, there was widespread intermingling and gene flow between different Native American groups as tribes migrated and settled across the Americas.
The First Americans
Genetic studies confirm that the first Native Americans descended from populations in East Asia that moved across the Bering Land Bridge into North America starting around 15,000 years ago. These pioneer groups branched off from East Asians sometime between 23,000 to 40,000 years ago and remained genetically isolated in Beringia for thousands of years before dispersing throughout the Americas.
The earliest Native American ancestors derived primarily from populations related to modern northern Asians, like Siberians. Genes linked to Siberian tribes like the Kets, Selkups, Nganasans, and Yakuts are found in many Native Americans. However, there was also mixing with ancient southern East Asians before crossing into the Americas.
This East Asian ancestry accounts for most of the genetic makeup of indigenous peoples in the Americas. For example, genome-wide analyses estimate that between 70-90% of Native American DNA comes from ancient East Asians. The exact ratios vary between tribes and geographic regions.
Beringian Isolation
After separating from other East Asians, the groups that gave rise to Native Americans were isolated in Beringia for up to 15,000 years. Interbreeding within this limited founding population resulted in unique genetic signatures found in modern tribes. The “Beringian” genetic component makes up 10-20% of indigenous DNA across the Americas.
Population Bottlenecks
Additionally, Native American genomes reflect two distinct population bottlenecks that limit their overall genetic diversity relative to other groups:
- First bottleneck – When tribes crossed from Siberia into North America, many populations died out, leaving a smaller genetic pool.
- Second bottleneck – After spreading through North America, only a subset of tribes managed to cross Central America and enter South America, causing another reductions in genetic diversity.
These twin bottlenecks are why Native Americans have around 86% less mitochondrial diversity than indigenous Africans and only 72% of the diversity found within Europeans.
Post-Contact Gene Flow
After the initial peopling of the Americas from Siberia, most Native American tribes remained genetically isolated until European contact in the late 15th century. Extensive mixing and intermarriage occurred between Native Americans and colonizing populations after 1492, especially within North America.
Europeans
Most North American Native Americans today have some European admixture in their genomes. The percentages vary significantly between individuals and tribal groups depending on historical contact with settlers.
For example, an analysis of the Lummi Nation and other Northwest tribes found that European admixture ranged from negligible levels up to 50%. Certain tribes with the most interaction with British and French fur traders after the 16th century had as high as 95% European mixture.
European DNA is found through South America as well, although at generally lower levels than in North American tribes. An average of 10% European ancestry, primarily Spanish, is detected in mestizo populations in Mexico, Colombia, Ecuador and other Latin American countries.
Vikings
Norse Vikings briefly established settlements in Greenland and modern Canada around 1000 CE. Gene flow from Vikings has been documented in a few East Coast tribes, including:
- Mi’kmaq – a Canadian Maritime tribe with possible Norse DNA markers.
- Beothuk – a now extinct Newfoundland tribe that showed significant Norse genetic mixing.
However, Vikings had a relatively isolated impact compared to later European settlers. Most North American tribes lack any clear Norse genetic influence.
Russians
In Arctic North America, Inuit and Aleut populations intermixed with Russian explorers and fur traders. Russian contact started in Alaska in the mid-18th century. By the late 19th century, Russian settlements were established across the Pacific Northwest and Alaska.
Around 25-38% of indigenous mitochondrial DNA in northeastern Siberia and Alaska comes from post-contact admixture with incoming Russian women. The genetic exchange was primarily between Russian men and native women, as evidenced by Y-chromosome data.
Africans
During the colonial period, some Native American groups intermixed with African slaves brought to the Americas by Europeans. This genetic exchange is most documented among tribes that had close historical ties with African-American communities.
For instance, the Seminole tribe of Florida, formed from various remnant tribes in the early 18th century, has significant African admixture derived from escaped slaves. Genetic studies estimate 12-14% African ancestry among the Seminole.
Similar patterns of African admixture resulting from intermarriage are found in other tribes along the Atlantic coast and American South, including:
- Houma Indians of Louisiana – 14% African ancestry
- Catawba tribe of South Carolina – 4-8% African ancestry
- Chickasaw tribe of Oklahoma – 4% African ancestry
However, African admixture is very limited in Northern tribes outside these close regional contacts with African-American populations.
Intermixing Between Native Groups
In addition to mixing with outside groups after European contact, extensive gene flow took place between diverse Native American tribes as they migrated across the continents over thousands of years.
As tribes expanded into new territory and splintered into daughter populations, previous genetic differentiation was erased by intermarriage between tribes. Even groups separated by thousands of miles can show biological ties.
Settling the Americas
Native American genomes indicate two major migrations southward from Beringia:
- First migration – Followed the Pacific Coast to populate Central and South America. Left genetic traces in tribes like the Algonquians of Canada, Yanomami of Brazil, and Yaghan of Chile.
- Second migration – Moved through an interior ice-free corridor into the rest of North and South America. Associated with genomes of Sioux, Navajo, Andes mountain tribes, and the Inca.
As each wave dispersed across new lands, migrating subgroups split apart but retained ancestral connections. The shared ancestry explains linguistic and genetic links between geographically distant tribes.
Post-Columbian Migrations
After European contact, many tribes were displaced and forced to relocate westward. This created new genetic mixing between previously isolated groups.
For example, tribes like the Shawnee, Kickapoo, and Chippewa moved from the Northeast woodlands into the Midwest and intermarried with Plains natives. This increased genetic similarities between Eastern seaboard and interior continental tribes.
Additionally, tribes like the Five Civilized Tribes (Cherokee, Chickasaw, Choctaw, Creek, and Seminole) were forcibly relocated from the Southeastern U.S. to Oklahoma in the 1800s. Their merging created new genetic connections with Western tribes.
Shared Ancestry Data
Genetic testing databases allow mapping of biological relationships between different tribal groups. Some examples:
- Tribes across the U.S. Southwest like the Pima, Tohono O’odham, and Navajo share common descent from ancestral settlers of the region.
- Great Lakes tribes including Ojibwe Chippewa, Potawatomi, and Ottawa have high genetic correlations, indicating common ancestral origin and intermarriage.
- Eastern tribes like the Ojibwe, Choctaw, and Cherokee have DNA ties to Plains tribes like the Cheyenne, illustrating post-contact mixing.
Despite speaking completely different languages and being widely dispersed, many Native groups show distinct genetic similarities.
Regional Variations in Ancestry
While the same core ancestral components are found across the Americas, proportionate genetic makeup often varies between different geographic regions.
Arctic Peoples
Arctic populations in Alaska, Northern Canada, and Greenland derive most of their ancestry from Siberian peoples distinct from other Native American founding groups. They have higher proportions of Siberian/Beringian DNA compared to southern tribes.
Arctic groups also universally show European admixture from contact with Russians or Vikings.
Canadian First Nations
Most Canadian tribes have around:
- 75-90% ancestral Native American DNA
- 10-25% European DNA
Atlantic Canada tribes like Mi’kmaq and Beothuk have higher European admixture, while Western tribes have higher Native American ancestry. There are regional variations in ancestral origins among the Native Canadian DNA as well.
United States
Native American ancestry ranges from 50% to over 90% in different U.S. tribes. European admixture tends to increase from West to East:
- Western tribes like Hopi and Navajo retained over 90% indigenous ancestry.
- Eastern woodland tribes like Choctaw, Creek, and Seminole have 60-80% Native American ancestry.
- Heavily displaced Southeastern tribes often have around 50/50 European/Native ancestry.
There are also regional variations in ancestral origins, with Western tribes showing more genetic sharing with Central Americans.
Mesoamerica
Most Mesoamerican populations have:
- 70-90% Native American DNA
- 10-30% post-colonial European DNA (mainly Spanish)
Southern Mexico tribes tend to have higher proportions of Native ancestry, while those in urban areas have higher Spanish admixture. There are traces of ancient mixing with groups from coastal migrations or the Amazon as well.
South America
The genetic makeup of South American tribes varies between:
- 70-95% ancestral Native American
- 5-30% post-colonial European, African, or Asian DNA
Groups with histories of isolation like the Yanomami of Brazil and Q’ero of Peru cluster closer to 100% indigenous ancestry.
Central Andes inhabitants have genetic ties to ancient Andean civilizations. Western coastal groups show more mixing with Asian, Polynesian, and European immigrants over the centuries.
Conclusion
In summary, Native American genomes are derived from diverse ancestral source populations:
- Most DNA traces back to ancient Siberian peoples who crossed into North America starting around 15,000 years ago.
- This ancestral DNA includes a unique Beringian component from isolation in the Arctic for thousands of years.
- There was widespread secondary contact and gene flow with Europeans, Africans, Asians, and other Native groups after initial settlement.
- But most indigenous ancestry still derives from the original founding peoples from East Asia.
While geographically and culturally diverse, most Native Americans share deep genetic ties stretching back 15 millennia or more.