At a glance:
- By STEPHANIE DUTCHEN
- DNA analysis of African Americans buried at an early U.S. iron forge reveals locations of their African and European ancestors and finds more than 40,000 living U.S. relatives.
- The study - led by Harvard University, the Smithsonian Institution, and 23andMe - is the first to link up ancient DNA technology with a personal ancestry testing database and use a new method for determining genetic relationships.
- The work, which followed rigorous ethical guidelines, was inspired by groups seeking to restore ancestry knowledge to African American communities.
A first-of-its-kind analysis of historical DNA ties tens of thousands of living people to enslaved and free African Americans who labored at an iron forge in Maryland known as Catoctin Furnace soon after the founding of the United States.
The study, spurred by groups seeking to restore ancestry knowledge to African American communities, provides a new way to complement genealogical, historical, bioarchaeological, and biochemical efforts to reconstruct the life histories of people omitted from written records and identify their present-day relatives.
Described Aug. 4 in Science, the work reveals how 27 individuals buried at Catoctin Furnace were related to each other, the genetic conditions they may have had, where in Africa and Europe they or their ancestors likely came from, and where in the U.S. they have descendants and other genetic relatives living today.
"Recovering African American individuals' direct genetic connections to ancestors heretofore buried in the slave past is a giant leap forward both scientifically and genealogically, opening new possibilities for those passionate about the search for their own family roots," said study co-author Henry Louis Gates Jr., the Alphonse Fletcher University Professor and director of the Hutchins Center for African & African American Research in Harvard University's Faculty of Arts and Sciences and host of the genealogy and genetics TV show Finding Your Roots.
Until now, genetic insights into the identities and ancestries of early African Americans were limited to what could be gleaned from mitochondrial DNA, which is passed down through mothers; from Y-chromosome DNA in males; and from comparisons to DNA sequences in moderately sized public databases that often lack sufficient numbers of Black participants.
The new study makes an advance by sequencing sites from across the historical individuals' entire genomes, comparing the sequences to a database with de-identified DNA information from more than 9 million living people, and using a new method to determine how genetically related people are.
The work - the first to link up ancient DNA technology with a personal ancestry testing database and to use the new algorithm - was made possible by a collaboration among researchers from Harvard, the Smithsonian Institution, and the genetic testing company 23andMe.
"Our study combines for the first time two transformative developments in genomics in the last decade: ancient DNA technology, which makes it possible to efficiently sequence whole-genome data from human remains, and direct-to-consumer genetic databases that contain data from millions of people who have consented to participate in research," said co-senior author David Reich, professor of genetics in the Blavatnik Institute at Harvard Medical School and professor of human evolutionary biology in Harvard's FAS.
"This work demonstrates the power of DNA to provide information about ancestral origins," he added.
The authors have made the Catoctin Furnace data publicly available for other researchers and amateur geneticists. However, they caution that establishing genetic relationships between living people and those from Catoctin should be handled with the utmost sensitivity, as outlined in a companion paper published in the American Journal of Human Genetics and in a Q&A from study co-author Roslyn Curry, a Harvard Kenneth C. Griffin Graduate School of Arts and Sciences student in the Reich lab and former 23andMe intern.
