Scientists have developed a groundbreaking map of strontium isotopes across sub-Saharan Africa, offering a potential tool for descendants of enslaved people to trace their family histories. This new research could help answer the question: “Where were my ancestors from?”
For Andre Kearns, this question has been a lifelong pursuit. He recalls a middle school geography assignment where he was tasked with coloring in New York City’s ethnic enclaves. When he shaded a Black neighborhood, his teacher instructed him to focus on Irish, Greek, and Italian immigrants, leaving Kearns confused but curious. This moment spurred his interest in his lineage, which led to a significant breakthrough: Kearns traced his family roots back to the early trans-Atlantic slave trade, learning that his maternal ancestors, Emanuel and Joan Cumbo, were enslaved in Virginia around 1628 and arrived from Angola.
However, Kearns acknowledges that much of his family history remains hidden due to a lack of records for enslaved people. He can trace his free ancestors through various public records, but finding specific details about his enslaved ancestors is much harder. Unlike genetic testing, which links people to broad regions, strontium isotope analysis could help pinpoint more specific geographic origins.
Strontium isotopes—found in the earth, water, and plants—are absorbed into the bones and teeth of animals, and humans can store these isotopic signatures as well. By comparing the isotopes in a person’s teeth with a map of strontium signatures across the landscape, scientists can trace the region where an individual likely came from. After over a decade of work, anthropologist Vicky Oelze and her team have compiled a detailed map of strontium isotopes across sub-Saharan Africa, which could provide important insights into the origins of enslaved Africans and serve as a resource for genealogists like Kearns.
Historically, tracing family history for descendants of enslaved people has been fraught with challenges. Enslaved individuals were often recorded only as a count, and early U.S. census records identified them solely by age, sex, and race. Genetic testing has helped some uncover distant relatives or regions of ancestry, but its accuracy is limited by the lack of African samples in testing databases and the challenges of correlating genetic data with historical origins. DNA alone cannot reveal precise ancestral locations, especially over long periods.
Strontium isotope testing, however, provides a more precise way to track origins. Researchers can analyze tiny samples of bones or teeth to pinpoint an individual’s region of origin based on the unique strontium signature from their childhood environment. This technique has already been used to uncover the origins of enslaved people buried in Charleston, South Carolina, and Rio de Janeiro, Brazil, offering a more refined understanding of where they came from.
The research has significant implications for understanding the history of the trans-Atlantic slave trade. For example, scientists recently used the strontium map to estimate the African origins of individuals buried in Charleston and Brazil. By cross-referencing isotope data from enslaved people’s remains with the map, they identified specific regions in Guinea, Ghana, and Angola, shedding light on the wide-reaching networks of the slave trade.
While this method offers new possibilities for understanding the past, it also raises ethical considerations. Anthropologists and archaeologists are increasingly mindful of the colonial history of anthropology and the need for accountability to descendant communities. The African American Graves Protection and Repatriation Act (AAGPRA) is a call to ensure that remains are treated with respect and that descendant communities have a say in how their ancestors are studied.
For many descendants like Kearns, the promise of strontium isotope research lies in its potential to provide a more detailed picture of their ancestors’ origins. Kearns reflects, “For me to know who I am, I need to know who came before me.” He believes that understanding his ancestors’ lives gives him important perspective and inspiration, reinforcing the idea that he stands on the shoulders of those who came before him.
Despite its promise, Oelze cautions that the strontium map is not a magic bullet. It provides estimates based on probabilities, and additional data and multi-isotope analysis may be needed to increase accuracy. However, when combined with other research methods—such as genetic testing, historical records, and oral histories—the strontium map has the potential to help reconstruct the personal stories of enslaved people with greater precision and depth.
This approach offers hope for those seeking to uncover lost histories and reconnect with their ancestral roots, helping to reveal the complex, often hidden, histories of the millions of African people who were abducted during the largest forced migration in history.
