If your ancestry in the United States stretches back more than 250 years, you may have Native American forbears. A new population genetics study shows that Americans with early European or early African ancestry can also have Native American gene groups.
Those Americans usually have family roots near the traditional homes of the respective tribes found in their genes, according to research led by the Georgia Institute of Technology. But where the descendants are today differs between these groups.
“People of Western European heritage have Native gene sequences from tribes that were located near where they now live,” said Andrew Conley, who led the study and is a research scientist in Georgia Tech’s School of Biological Sciences. “For African descendants, Native American ancestry looks like it came from regional groups of Native Americans in the southeastern United States.”
Many Americans descending from enslaved Africans later left the South in the Great Northward Migration, took those Native American sequences with them, and apparently no longer significantly reproduced with indigenous populations.
Americans with European heritage going back to Spain, mostly people who immigrated to the U.S. from Mexico, carry sequences from Native American ancestors who were traditionally located in what is Mexico today. This group also carries the most Native American genetic sequences by far, roughly 40% of their total genome, according to the study.
The researchers came to their conclusions by tracking haplotypes, patterns of genetic variants that are passed on by one parent, and that are typical for certain regions and peoples. They published their results in the journal PLoS Genetics on September 23, 2019.
“Haplotype combinations are very different between European, African and Native American ancestries and specific to locations,” Conley said.
The data was extracted from a much larger study, The Health and Retirement Study, sponsored by the National Institute on Aging (NIA) and conducted by the University of Michigan. That study also followed health and finance over time but included genomes and geography. Neither the NIA nor Michigan was part of the Georgia Tech study.
Americans of early African heritage have about 1.0% and of Western European heritage about 0.1% Native American haplotypes, though the difference in those numbers can be deceiving. The native ancestry probably lies a similar number of generations back for both groups.
“With African Americans, it correlates to about eight to nine generations back and probably ends there,” Conley said. “With Western European ancestors, we think about eight to 10 generations ago, and the contact with Native Americans could have also been more continuous.”
Further immigration from Europe likely dropped the percentage of Native American ancestry for the overall sample of Americans with Western European heritage.
“Particularly in the Mid-Atlantic and the Northeast there is almost no Native American ancestry among European descendants,” Conley said. “When you go out West, that’s where you have the most Native American ancestry in European populations.”
There was also an outlier group with European heritage from Spain.
“In parts of the Southwest, there are people of Spanish descent with also distinctive Native American ancestry. These groups call themselves Hispanos or Nuevomexicanos,” Conley said. “Their native American ancestry does not come from present-day Mexico. There were Spanish settlers in the region 400 years ago, and they could be the European ancestors of the Nuevomexicanos.”
The following coauthors from Georgia Tech collaborated on the study: King Jordan and Lavanya Rishishwar. Any findings, conclusions, or recommendations are those of the study’s authors.
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