Archaeological studies of DNA usually focus on human remains such as bone and teeth. However, geneticists are now able to extract DNA that is hidden inside ordinary objects, which can contain centuries-old saliva.
Archaeologist Julie Schablitsky recently analyzed the DNA from a 19th-century tobacco pipe, which was found in the slave quarters of a Maryland plantation called Belvoir. Tobacco pipes were ubiquitous in the 17th, 18th, and 19th centuries and are not hard to find, says Schablitsky. “Wherever these people left broken tobacco pipes, they were also unwittingly leaving their DNA.”
The DNA showed that a woman had used the pipe, and her genetic ancestry most closely matched people living in Sierra Leone. The woman was most likely enslaved on the plantation.
While excavating the slave quarters, Schablitsky and her team collected clay 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. DNA only sits on the surface of metal artifacts, such as forks or jaw harps, so it’s unlikely to still be present after decades in the ground.
Four pipe samples were sent off to an ancient DNA lab at the University of Illinois at Urbana-Champaign for DNA testing. One of the samples yielded enough DNA for further analysis. Unfortunately, the DNA was still too degraded to link to individuals alive today. However, the Illinois lab got in touch with Hannes Schroeder at the University of Copenhagen, who specializes in working with ancient DNA.
Using the DNA taken from the pipe, Schroeder used algorithms to compare the genetic material with modern African reference populations. The results showed that the woman in Belvoir was most similar to the Mende people in Sierra Leone.
Filling in the gaps
The research on ancient DNA has invested artifacts with new significance. The DNA in the clay pipe, for example, contains within it a record of the transatlantic slave trade. “You start with one small insignificant piece of tobacco pipe and you end up talking about one of the most significant events in American history”, says Schroeder.
Because the use of tobacco pipes was so widespread, Schablitsky hopes that fellow archaeologists will start using them as a source of old DNA to fill gaps in history. For example, few records exist of exactly where in Africa enslaved people came from.
Theresa Singleton, a professor at Syracuse University who studies the archaeology of slavery, said the discovery in Belvoir holds great promise for future research, but the cost of DNA analysis may be prohibitive for some archaeologists.
Another limitation is that geneticists have historically sampled relatively few Africans. This means that the reference database for Africans and also for the diaspora is still very poor. The woman in Belvoir most closely matched Mende people in the existing reference database, but she might be more closely related to another group whose DNA is not even in the database. The only way to know is to go out and collect more samples. This problem is compounded by the fact that people in Africa are more genetically diverse than people from other continents. For information on AlphaBiolabs’ complete range of DNA testing services, call us now on 727-325-2902 or email us at firstname.lastname@example.org.
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