The great thing about tobacco pipes, according to Julie Schablitsky, is that they are hard to not find. They were ubiquitous in the 17th, 18th, and 19th centuries—to the point, she says, that “wherever you have people during this historic period, you’ll find these clay tobacco pipes in the ground.” And wherever these people left broken tobacco pipes, they were also unwittingly leaving their DNA.
Traditionally, the archaeological study of DNA has focused on human remains such as bone and teeth. But geneticists are now able to extract DNA hidden inside ordinary objects, including tobacco pipes, which can contain centuries-old saliva. Schablitsky, an archaeologist with the Maryland State Highway Administration, and her collaborators recently analyzed the DNA from one such 19th-century pipe—uncovered in the slave quarters of a Maryland plantation called Belvoir.
The DNA showed that a woman had used the pipe, and her genetic ancestry most closely matched people living today in Sierra Leone. She was most likely enslaved on the plantation.
Schablitsky got the idea to analyze DNA on the pipe from talking to descendants of people enslaved at Belvoir. When her team first found the slave quarters in 2014, they got in touch with a historian who specializes in local African American history and spread the word. The news eventually reached Shelley Evans, a retired Baltimore City schoolteacher. She had found records of her ancestor Thomas Burley, a freeman, buying his wife and daughter out of slavery at Belvoir. “My third great-grandmother, she lived here,” says Evans. “She was born there. Her mom and dad had to have been there as well.” The pipe could have belonged to one of her ancestors.
So while excavating the slaves’ quarters, Schablitsky and her team collected pipe fragments, using sterilized forceps to prevent contamination. They particularly focused on the pipes, because clay is porous, which means the DNA in saliva can easily penetrate inside. By contrast, DNA only sits on the surface of metal artifacts such as jaw harps or forks, and it’s unlikely to be present after decades in the ground.