DNA: Transforming African American Genealogy
In 2006, PBS aired a television program called African American Lives in which Henry Louis Gates Jr. explored the genealogies of prominent African-Americans. In this mini-series, Gates used traditional genealogical research in combination with DNA analysis to reveal secrets about his guests’ family histories.
As a genetic genealogist myself, this series was both awe-inspiring and eye-opening. It was a key factor in my own decision to pursue a career in genetic genealogy. To think that each one of us carries a biological record of our ancestry in our cells intrigued me. That DNA could tell many African-Americans the approximate origins of their direct-line maternal and paternal ancestors fascinated me. I learned that even if the lack of historical records may obscure our vision of our ancestors’ lives, the biological record in our DNA can still reveal precious clues regarding their origins and history.
Genetic genealogy has grown dramatically since 2006 when African American Lives first aired, and with its growth, DNA testing has gradually become a common and often indispensable element of African-American research.
The field of African-American genealogy is wrought with challenges. Beyond the emotional difficulty of the subject matter – dealing with records which describe the captivity and subjugation of human beings – African-American genealogical research is also difficult because of a scarcity of records. Add to this the widespread record destruction in the Southern United States in general, and tracing African ancestors can be a formidable task. This is where DNA testing comes in! Following are the three types of genetic testing and their uses:
The Y-chromosome is inherited along a line of direct paternal descent. Males receive this type of DNA from their father who received it from his father and grandfather in an unbroken chain. Occasional mutations on the Y-chromosome from one generation to another help to distinguish different Y-chromosome lineages. These lineages are grouped into larger groups of lineages called haplogroups. Y-DNA haplogroups most commonly found in Africa include A, B and E, as well as subgroups of other haplogroups.
Many African-Americans, when they perform Y-DNA testing, discover that their Y-chromosome is of European origin. This has been attributed to the common practice among slave-owners of fathering children by their female slaves. Since the Y-chromosome often follows the same patrilineal inheritance of surnames, Y-DNA testing can often connect African-Americans to the slave-holding ancestor to whom their direct-line paternal ancestor belonged. This is a key piece of information in traditional African-American research.
One prominent case, and one of the hallmark studies in the history of genetic genealogy, showed that Thomas Jefferson was in fact the father of his slave, Sally Hemings’ children. A male descendant of Sally’s youngest child, Eston, was found to share the same unique Y-chromosome signature as a descendant of Thomas’ uncle, Field Jefferson. This discovery caused a shift in the consensus among biographers and historians of Thomas Jefferson and consequently changed the way we view American history.
Though many African-American males find that their direct-line paternal ancestry is European, about 65% of African-American males have Y-chromosomes that trace back to Africa. Subgroups of common African haplogroups are more frequently found in specific African populations and can sometimes be used to identify the likely origins of an individual’s direct-line paternal African ancestor.
Like the Y-chromosome, mitochondrial DNA is passed on intact from generation to generation, and occasional mutations distinguish different lineages into mtDNA haplogroups. The most common mtDNA haplogroups in Africa are haplogroups L1, L2 and L3. Unlike the Y-chromosome, which is inherited along the direct paternal line, mitochondrial DNA is inherited along the direct maternal line. Every individual receives mtDNA from their mother, who inherited it from her mother and grandmother in an unbroken maternal line.
Most African-Americans, when they test their mtDNA, discover that it traces back to Africa through haplogroup L. Some find that it traces back into Native American lineages including haplogroups A,B,C or D. Like Y-DNA, some mitochondrial sub-haplogroups are only found in high numbers in specific areas of Africa. Therefore, mitochondrial DNA testing can sometimes suggest likely geographic origins of a direct line maternal African ancestor.
In the last season of Finding Your Roots on PBS, two African-American guests discovered unique information about their mtDNA. Dancer and actress Khandi Alexander’s mtDNA revealed shared direct-line maternal ancestry with individuals living in modern-day Ethiopia in eastern Africa – a very unique result for someone with African-American ancestry, since most slaves came from West Africa.
Political activist Ben Jealous discovered that his mtDNA had two mutations that were very specific to individuals living in Madagascar. From this result it was determined that his direct line maternal African ancestor was most likely a woman who was brought on one of just 17 slave ships which transported slaves from Madagascar to Virginia and New York between 1678 and 1721. Since Ben’s closest mitochondrial DNA matches are all African-American and Madagascan, his other African-American matches also likely have direct-line maternal ancestors who arrived on one of these same slave ships during the same time period.
Each person receives half of their autosomal DNA from their mother, half from their father, and about half the previous amount for each subsequent generation.
When individuals test their autosomal DNA, they are given a breakdown of ethnicity estimates and compared to a database of other individuals who have tested. These ethnicity estimates show the percentages of DNA that originate from different areas of the world. After comparison to the database, each individual is given a list of genetic cousins which are determined by the amount of DNA that they share in common with other test takers.
Ethnicity results typically deal with large population clusters, but the DNA testing companies do not offer more specific descriptions of tribes or localities and, as a result, are not as useful for identifying the specific areas of Africa where a person’s ancestors may have come from.
Match lists, on the other hand, can provide more specific information about ancestral origins of African-American ancestors. Through lists of genetic cousins, it is often possible to identify the slave-holding European families who may be among an African-American’s own ancestors.
As more individuals test, and as DNA testing becomes a worldwide phenomenon, African-Americans may begin to see more matches who still reside in Africa. In 2013, 23andMe announced the African Ancestry Project, which offered free tests to individuals with four grandparents from Sub-Saharan Africa, in hopes that this might help African-Americans connect with the largest source populations during the transatlantic slave trade.
Even now, autosomal test results for African-Americans have begun to reshape the way we view race relations and African-American ancestry in the United States. In January 2015, 23andMe published an article in the American Journal of Human Genetics, which used the genetic data of 160,000 23andMe customers, including more than 5,000 self-identified African-Americans. Through this study, 23andMe mapped levels of Native American, African, and European ancestry among these self-reported groups. They found that many individuals who had self-identified as African-American had at least 1% Native American DNA. They also found that on average, African-American individuals had about 24% ethnic admixture from European populations. Among other populations they found that on average, Latinos had 6% African admixture and Europeans had .19% African admixture. However, there were certain regions of the United States where these percentages were much higher. Other studies have also shown various admixture percentages among Caribbean, Central American and South American countries.
These results and others nuance our views of racial identity in the United States. For example, Henry Louis Gates, in the last season of Finding Your Roots, discovered that one of his own European ancestors was a white man by the name of William Mayle, who immigrated to Virginia from England. In 1826, he emancipated and publicly “married” his slave Nancy, despite the fact that interracial marriage was then illegal in Virginia. Mayle and his wife eventually went on to found a large community of mixed-race families in West Virginia known as the Chestnut Ridge People. Later in life, Mayle himself, who began life as an Englishman, was variously recorded as white, mulatto and colored. Though perhaps an isolated case, Mayle’s experience varies from the commonly assumed situations of coercion and rape which are the most common explanations for European admixture among African-Americans.
The Ideal Tool
Genetic genealogy is the ideal tool for helping African-Americans connect with their African, European and Native American heritage. DNA tests can help people connect with their African roots through unique Y-DNA and mtDNA haplogroups. They can help researchers identify their European slave-holding ancestors, and they can help them connect with and contribute to the national narrative of American history. As genetic genealogy becomes an increasingly integral part of African-American family history research, additional discoveries will likely surface that change and contribute to our views of family histories, national histories and world history.
 Henry Louis Gates Jr. African-American Lives, PBS, February 1-8 2006, Television.
 Eugene A. Foster, et al. “Jefferson fathered slave’s last child” in Nature. 1998 396 (6706): 27-28
 CeCe Moore, “Telling Stories with Mitochondrial DNA,” Finding Your Roots Blog, http://www.pbs.org/wnet/finding-your-roots/blog/telling-stories-mitochondrial-dna/ (accessed 11 February 2015).
 ScottH, “23andMe’s African Ancestry Project” 23andMeBlog http://blog.23andme.com/23andme-research/23andmes-african-ancestry-project/ (accessed 11 February 2015) published 1 November 2013
 Katarzyna Bryc, et al. “The Genetic Ancestry of African-Americans, Latinos and European Americans across the United States” American Journal of Human Genetics. 2015 January 8; 96(1): 37-53.
 Henry Lewis Gates Jr. “Decoding Our Past Through DNA” Finding You Roots Season 2, PBS, 2014.