In Ancient DNA, New Directions for African American History

Nestled at the foot of the Catoctin Mountain of the Appalachian Mountain Range are the remains of the Catoctin Furnace, once the heart of a lively iron forging village. Speckled with trees, woodland debris, and a few field stones, the land beyond the furnace seemed perfect ground for a new highway project in the late 1970s.

But during a pre-archaeological survey for the project, the Maryland State Highway Administration made an unexpected discovery: Underneath the soil lay the unmarked graves of 35 enslaved African American laborers.

More than 50 years later, those individuals became the subject of an event at Harvard University, titled “Ancient DNA & U.S. History: The Genetic Legacy of African Americans from Catoctin Furnace.”

Evolutionary biologists, historians, population geneticists, and archaeologists gathered on Feb. 7 to discuss new genetic findings, published last fall in an article in “Science,” that enabled researchers to peer into the lives of the individuals who were buried at the Catoctin Furnace Cemetery. The room was packed — after the seats ran out, attendees sat in white folding chairs in the back. The air buzzed with the excitement of revived history.

“We are embedded in the past,” professor Michael McCormick, chair of the Science of Human Past Initiative, says in his opening remarks. “The past is embedded within us.” The initiative’s event expanded on the work of the Reich Lab and Catoctin Furnace Historical society, providing context and a starting point for future connections between scientists and historians.

To rectify historical amnesia, researchers aimed to identify the countries of origin that the enslaved workers were forcibly displaced from and to find potential descendants.

But closing the gaps of history is no easy task. The Catoctin Furnace began operating in time to produce ammunition for the Continental Army’s victory in the Battle of Yorktown. In the years of its operation, the furnace was a bastion of industrialism in an agrarian South. Hundreds of enslaved people worked at the furnace, providing skilled labor as blacksmiths, forgers, agrarian laborers, and domestic servants for the ironmasters and their family. The family who built the forge enslaved over 80 people, but few records of the free and enslaved African Americans who worked at the cemetery remain.

“Black labor, both enslaved and free, produced ironworks, tools, munitions for the Revolutionary War,” says Evelyn Brooks Higginbotham, professor of History and African American Studies. “It’s an important chapter because it tells of their contributions to the earliest industries, namely, iron manufacturing in America.”

“Now, as a scholar of African American history, I see the Catoctin Ffurnace article as a harbinger of new directions in my field, and especially in the burgeoning field of African American family history,” Higginbotham adds.

Previous studies using the skeletal remains of the Catoctin Furnace workers were limited. Before 2010, it was impossible to sequence the ancestral DNA of human remains. One study, which began in 2015, focused on osteological analyses, reconstructing the histories and identities of the furnace workers through their bones and teeth. Now, researchers are able to analyze ancient DNA “of the quality that you get when you send your spit sample to a personal ancestry testing company,” says Professor Reich, “from material that is one hundred years old, a thousand years old, even ten thousand years old.”

The 2023 article relied on two major advances in ancient DNA analytics. Researchers used the process of imputation, which uses known sequences in the ancient DNA and reference databases of high quality DNA to infer what fills those missing gaps. Then, scientists used 23andMe’s identical by descent technology and vast database of DNAto match identical segments of ancient DNA with those of living descendants of the Catoctin workers.

This gave historians key insights into the migration patterns of enslaved Africans, before and after the Civil War. The researchers traced the Catoctin ancient DNA to Senegambia and West Central Africa, by comparing their samples to the DNA of people living in those regions today. With the help of historians, the researchers were able to contextualize the Catoctin Furnace within the trans-Atlantic slave trade. The individuals’ ancestry did not align with that of most enslaved people in the Chesapeake region, most of whom came from the Igbo and Yoruba tribes native to present-day Nigeria. They also found that a majority of the direct descendants of the Catoctin laborers still resided in Maryland.

These novel insights are a testament to the interdisciplinary nature of the project. “There’s a lot of these moments where we come back with something, we say, ‘Oh, this is kind of interesting,’” Dr. Harney says. “And [the historians and archeologists] say, ‘No, no, this is really interesting for this reason.’”

The ancient DNA research has the potential to change the ways museums, universities, and other institutions interact with human remains. However, genetic studies cannot tell us about non-familial connections and are severely limited by a lack of publicly accessible data.

In addition, there are concerns about biological privacy and informed consent, as Harney explains in a paper on the ethics of ancient DNA methodology. Though more than 80 percent of 23AndMe’s customers consent to having their survey responses and genetic data used for research purposes and be contacted based on findings, Harney suggests that genetic researchers have database members “opt-in” to hear about potentially traumatic DNA results.

The event, fittingly, ended with questions from two Catoctin descendants in the audience. One asked about the possibility of learning which specific ancestral lines they came from. The answer, from Harney, was that the methods used in the paper were still being perfected, so they could not fully confirm genetic connection. Before the other descendant’s question could be asked, the event ended. The second question remained unanswered.

— Magazine writer Annika Inampudi can be reached at annika.inampudi@thecrimson.com.