Science Matters

Tracing DNA links at Catoctin Furnace

Boyce Rensberger

(4/2024) Sometime between 1776 and 1840, a three-year-old girl died at the Catoctin Furnace near Thurmont. Today the furnace is preserved as a historic site, but back then it was a booming industrial complex, refining iron from ore and making various cast-iron products.

The little girl was the child of enslaved Africans who operated the blast furnace and made the products. What is remarkable today about that toddler is that we now know that she has several relatives currently living in Hagerstown. DNA revealed the connection.

Here’s how: First, the girl’s skeleton was one of 27 exhumed in 1970 for the widening of highway US-15. The road work cut through an overgrown cemetery used by Blacks more than a century earlier at the furnace. The skeletons then were housed at the Smithsonian. About ten years ago DNA was extracted from the bones. The child’s DNA proved to be purely African, suggesting that she or her parents had been brought directly from West Africa to America. (Africans, incidentally, were valued for their iron-making skills, derived from a technology practiced in Africa for more than 2,500 years.)

The bones’ genetic markers were then compared with those of some nine million people who had given their DNA samples (cheek cells in saliva) to 23andMe, a California company that does the analysis and maintains a database.

The analysis found nearly 42,000 living Americans who are related one way or another to that little girl. The evidence also revealed that 15 of the skeletons could be grouped genetically as members of five different families.

Of the living relatives of the little girl, one was Agnes Jackson, an 86-year-old resident of Hagerstown who had contributed her DNA to the database in 2022. And the toddler was, of course, also related to Jackson’s three daughters. The four of them came to Catoctin Furnace last summer to learn more about the research project and to see where their family had lived and worked.

"It’s so exciting to see my tree … to know more about our ancestors," Ms. Jackson told a reporter from Science magazine. "It’s always good to know where we came from."

Sharon Green, one of Jackson’s daughters, was struck by seeing the nails that were found with the child’s bones. They once fastened the wooden coffin that had long since deteriorated. "Seeing the nails that were buried with her, and hearing how much my ancestors were sold for, was amazing," she told Science. "It’s so overwhelming to know we contributed to this country and know who we were."

The DNA comparisons to the 23andMe database found thousands of other living relatives around the country, but the company feels that since those people haven’t given permission in advance to be linked to people who lived long ago, they are not at liberty to name them.

Seven other people buried in the cemetery had no detectable European ancestry, indicating that they were captives recently imported from Africa or immediate descendants of Africans. All the other skeletons contained DNA with some mixture of European ancestry.

Ms. Jackson and her daughters were not, of course, descendants of the three-year-old child. A geneticist from 23andMe, Éadaoin Harney, met the Jacksons at Catoctin Furnace and told them that long stretches of the girl’s DNA were identical to those in Agnes Jackson. There was enough overlap to conclude that Ms. Jackson was likely a third cousin, or a second cousin twice removed.

"What DNA does for the first time is connect a living, 21st century family not just to Catoctin, but to the actual cemetery," says Catoctin Furnace Historical Society archaeologist Elizabeth Comer. She is the one who in 2015 asked the Smithsonian’s Doug Owsley, a biological anthropologist, to see if new genetic testing methods could be tried on bones from the Catoctin cemetery. That led to DNA being extracted from the bones and submitted to 23andMe for comparison.

Comer’s actions and the DNA work were done in consultation with the African American Resources Cultural and Heritage Society, an organization dedicated to promoting knowledge of the history of African Americans in Frederick County.

Comer has also been instrumental in bringing attention more broadly to the slave cemetery and in finding ways to help people today connect with the ones long ago who lived and worked in our area. A few years back she persuaded the Smithsonian to allow two skulls, that of a woman and a teen-age boy, to be "fleshed out" in clay to create some idea of what those two looked like in life. The sculptures can be seen at the Museum of the Ironworker, a part of the Catoctin Furnace site.

Prior to the DNA work, Jackson’s family was already connected to the furnace through historical records. She knew that her great-great-grandfather was an ironworker named Henson Summers. His distinctive name helped genealogists trace his family. Born around 1820, Summers was enslaved by the owners of the ironworks and later sold to another furnace near Hagerstown, where Jackson and her daughters live today.

Without DNA analysis the little girl’s connection to anyone alive today would have remained unknown. "We can do genealogy research till the cows come home, but without DNA, we would never know that information," Comer says. "This closes the loop."

Three of the people buried at Catoctin Furnace had DNA associated with sickle-cell disease. Four had variants of a gene associated with another blood disorder called G6PD deficiency, which causes fevers, abdominal and back pain, and fatigue. Both diseases disproportionately affect people descended from sub-Saharan Africa.

"This study is an example of deploying scientific tools to address questions of long-standing interest to African Americans, at the community’s request," says Dr. Henry Louis Gates Jr., a professor and director of the Hutchins Center for African and African-American Research at Harvard. Referring to the ability of DNA studies to link Blacks to ancestors who lived before their names and dates were written into records, Gates told Science, "It is a tool for empowerment of African Americans, rather than exploitation of a vulnerable population. I think it is a model of engagement to be emulated."

Boyce Rensberger retired to New Midway after more than 40 years as a science writer and editor, mostly for The New York Times and The Washington Post. Write him at boycerensberger@gmail.com.