Newswise — Numerous Americans can track parts of their ancestry to the 1600s. Nonetheless, African Americans, whose origins stem from enslaved Africans that arrived in North America in 1619, lack extensive ancestral data covering numerous centuries.
A fresh Genetics study from USC and Stanford sheds light on the individuals occupying these absent branches within family trees, offering a glimpse into their abundance.
"The memories of our enslaved ancestors still linger in my family's tales, despite slavery being only a few generations past. They reveal who they were and, in my case, shed light on how our complexion became as light as it is," explained Jazlyn Mooney, the Gabilan Assistant Professor of Quantitative and Computational Biology at the USC Dornsife College of Letters, Arts and Sciences, and the first author of the study. "However, these accounts merely exist as narratives, representing what remains for most African Americans. We lack factual records or concrete figures. There is a dearth of tangible data."
Mooney finds the study particularly illuminating when it comes to her own family lineage. "Tracing my mother's side of the family back to the early 1500s is relatively straightforward," Mooney shared. She mentioned that her mother's family has roots in the medieval Jewish expulsion from Spain and belongs to a community that settled in New Mexico during the 1600s. However, when it comes to her African American father's side, the ability to trace their ancestry quickly diminishes due to the absence of genealogical records.
The reason for the difficulty in tracing the ancestry of enslaved African Americans lies in the fact that they were rarely included in official records. While the 1870 federal census did record the names of formerly enslaved African Americans, and it serves as a crucial resource for genealogical research, many African Americans still face challenges in tracing their family members to or beyond this particular document.
This study plays a crucial role in filling the gaps in an average African American's family tree. By employing computational methods guided by genetic data, researchers have estimated that a randomly selected African American born between 1960 and 1965 can trace their lineage back to an average of 314 African ancestors and 51 European ancestors, all the way to 1619. Jazlyn Mooney emphasized the significance of this study, stating that while the general outline of African American family trees is widely known, the specific numbers and estimates of enslaved Africans and Europeans involved in their ancestry provide a new perspective on the subject.
While the research does not identify the specific identities of the African and European individuals in question, the historical record can offer a broader narrative. For instance, it is known that numerous European ancestors are present in the family tree during the era of slavery, a time marked by pervasive sexual violence and the exploitation of enslaved women. Additionally, many of the African ancestors, whose identities cannot be traced through written records, are individuals who managed to survive the harrowing Middle Passage of the Transatlantic Slave Trade. These individuals endured imprisonment and were crammed into slave ships for journeys that could last up to 80 days, highlighting the immense challenges they faced.
To conduct the study, researchers created a 14-generation model divided into three time periods:
- The first period, 1619-1808, includes the founding of the African American population, with the population formed by Africans and Europeans.
- The second period, 1808-1865, is marked by the end of legal importation of enslaved African captives into the United States. The number of new African ancestors declines sharply, and the African American population continues to grow with contributions from Europeans and European Americans continuing.
- The third period, 1865-1965, begins with the end of legal enslavement and continues to many African Americans living today. With the end of legal slavery comes reduced contributions from the European and European-American sources; contributions from African sources remain low due to low immigration.
Co-author Noah Rosenberg of Stanford emphasized the significance of the method employed in the study, describing it as a powerful approach. While genetic ancestry studies typically concentrate on clustering the genomes of present-day individuals, this study takes a different approach. It models ancestry by explicitly considering the genealogical descent over time, providing a more nuanced understanding of how African American family trees have evolved throughout history. This approach adds depth and temporal context to the analysis of genetic ancestry.
The research also mentions that certain well-known African Americans, like Michelle Obama, were born between 1960 and 1965, as stated in their publicly disclosed ancestral records.
“It was helpful to think about these well-known people,” Mooney said.
Mooney mentioned that she and her colleagues are currently developing a computational model aimed at dissecting the numbers into their respective male and female constituents. This endeavor holds the potential to provide additional insights into the historical dynamics of the African American population.
"Additionally, we could delve into the inclusion of various ancestral components," stated Mooney. "For instance, certain African American individuals possess Native American lineage, and this aspect could be examined in our research as well."
About the study
In addition to Jazlyn Mooney and Noah Rosenberg, other authors of the study are Lily Agranat-Tamir and Jonathan Pritchard, both of Stanford. The work was supported by a grant from the National Science Foundation (BCS-2116322), by the National Science Foundation Postdoctoral Research Fellowship in Biology, by a Council for Higher Education of Israel Scholarship for Outstanding Postdoctoral Fellows in Data Science and by the Stanford Center for Computational, Evolutionary and Human Genomics.
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