December 22, 2014
America really is a “melting pot,” study says
John Hopton for redOrbit.com - Your Universe Online
Americans who identify themselves as being from distinct ethnic groups may wish to reconsider, following the findings of a new genetic study that show mixed ancestry may extend further than previously thought. The investigation also looked at regional distribution across the U.S. and found that it is consistent with certain events in American history.Many Americans who describe themselves as European in fact carry African ancestry, and the same applies in reverse. 6 million Americans who self-identify as European are now believed to carry African ancestry, while 5 million self-described European Americans might have at least 1 percent Native American ancestry, according to the study published in the American Journal of Human Genetics and reported on Discovery News (http://news.discovery.com/human/genetics/think-youre-all-european-or-african-most-are-mixed-141218.htm#mkcpgn=rssnws1).
The Harvard study used data from 23andMe, a Google-backed genetic testing firm, and based its conclusions on analysis of the genomes of more than 160,000 European Americans, African Americans and Latinos.
“Our study not only reveals the historical underpinnings of regional differences in genetic ancestry, but also sheds light on the complex relationships between genetic ancestry and self-identified race and ethnicity,” study author Katarzyna Bryc of 23andMe and Harvard Medical School said in a press release.
Building a genetic map of the USA, the researchers discovered that Scandinavian lineage makes up around ten percent of ancestry in European Americans in Minnesota and the Dakotas. Trace amounts can be identified in nearly all states, but this region’s percentage is much higher than most. Hundreds of thousands of Danes emigrated to the US during the second half of the eighteenth century and the early twentieth century, mostly for economic reasons. The peak came in the middle of that period when Minnesota and the Dakotas were popular destinations.
Meanwhile, the highest average percentage of African ancestry exists in Georgia and South Carolina. The concept of the ‘one-drop rule,’ the belief that anyone with even the tiniest amount of known sub-Saharan African ancestry should be considered black, is thought to still be held by many people of both European and African descent, and occasionally used nominally in legal situations. The new study, however, found that people tend to categorize themselves based on the majority of their genetic ancestry.
Bryc and her colleagues studied DNA sequence variations called “single-nucleotide polymorphisms” using saliva samples, where they found the DNA sequence variations. The study looked at the genomes of 5,269 self-described African Americans, 8,663 Latinos and 148,789 European Americans, and also had the participants complete surveys. Investigations along these lines have been lacking in the US to date compared with other parts of the world, because of the known complexities of American genetic melting pot.
“These findings suggest that many individuals with partial African and Native American ancestry have ‘passed’ into the white community, thereby undermining the use of cultural labels that separate individuals into discrete, non-overlapping groups,” Bryc said. “Taken together, our results suggest that genetic ancestry can be leveraged to augment historical records and inform cultural processes shaping modern populations.”