The Maryland Dove docked at Historic St Mary’s City, Maryland. This ship is a reconstruction of the Dove, a 17th-century trading vessel that, alongside the passenger ship the Ark, carried colonists to found Maryland in 1634. Credit: Jenn Dorsey, Historic St Mary’s City.

Historical DNA connects 1.3 million living relatives to 17th-century Maryland settlers and may have identified the colony’s second governor.

Analysis of Historic St Mary’s City highlights the power of combining ancient DNA, archaeology, and genealogy to restore lost identities and track the migrations of America’s earliest English colonists and their descendants

As the United States prepares to mark its 250th anniversary, researchers from 23andMe Research Institute, Harvard University, and the Smithsonian Institution have teamed up to study one of the country’s founding settlements: St Mary’s City, Maryland. 

Established in 1634, St Mary’s City was the first English settlement in the colony of Maryland.

Despite existing written records and the ability of many present-day Americans to trace their ancestry to the historic city, many gaps remain in our knowledge of this early founder population.

The study focuses on the genetic ancestry of 49 colonists who were buried in St Mary’s City’s Chapel Field cemetery between 1634 and 1730. 

By studying their DNA, the research team learned about the ancestral origins of this founding population and traced the migration of their descendants across the United States.

Using a novel approach that combines genetic connections to research participants in the 23andMe database with self-reported family history information, they even propose possible identities for three previously unknown individuals buried in the cemetery, including Maryland’s second governor, Thomas Greene.

Co-senior author David Reich, professor of genetics in the Blavatnik Institute at Harvard Medical School and professor of human evolutionary biology in Harvard’s FAS, said: “This work highlights the power of ancient DNA analyses to fill in gaps in the historical record.

“While written records are extraordinarily rich, genetic data can still address gaps in that record and yield surprises.” 

2010 image of the exterior of the reconstructed 1667 Brick Chapel at Historic St. Mary’s City. Credit: Donald Winter, Historic St Mary’s City.

Expanding the Calvert Family

Douglas Owsley, curator of biological anthropology at the Smithsonian’s National Museum of Natural History, said: “This project has been decades in the making, starting with the excavation of three rare lead coffins from the Brick Chapel.

“Years of interdisciplinary research eventually led us to team up with Harvard for DNA analysis, which became the springboard for these incredible new genetic discoveries.”

The lead coffins contained the remains of Philip Calvert, his first wife, Anne Wolseley Calvert, and an infant son, who the genetic analysis revealed to be the son of Calvert and his second wife, Jane Sewell.

The results of this genetic analysis were released in 2016 as part of a technical report, but are formally published for the first time in this study. 

Philip Calvert, who served as the colony’s fifth governor, was the youngest son of George Calvert, England’s first Baron Baltimore. The prominent Calvert family played a critical role in the founding of the colony of Maryland.

The colony was first envisioned by George Calvert as an expansion of the King’s realm and a place of religious freedom, especially for persecuted Catholics. The royal charter for the new colony was granted shortly after his death.

In 1633, the first settlers set sail for Maryland aboard the ships The Ark and The Dove, led by George’s son Leonard Calvert.

The travellers arrived at Maryland’s southern tip in 1634, where they founded St Mary’s City. While many members of the Calvert family are known to have travelled to St Mary’s City, only Philip’s burial location has been identified.

When comparing the DNA of Philip Calvert and his wife and son to the 46 other individuals included in this analysis, the research team identified three additional members of the Calvert family. 

Owsley said: “Although additional work is needed to determine exactly how these individuals were related to Philip, this finding is significant given that several members of the extended Calvert family, including Philip’s half-brothers Leonard (1610–1647) and George (1613–1634), died in St Mary’s during this period.”

The DNA study also identified related individuals belonging to five additional families buried at the site, including one that spanned three generations.

Owsley added: “Because mortality was so high in the early days of the colony, finding a multigenerational family was a surprise.

“It’s a discovery that simply wouldn’t have been possible without genetic study.”

Bringing history to life, this image overlays a forensic reconstruction of Anne Wolseley Calvert onto skeletal remains excavated from 17th-century St Mary’s City, Maryland’s founding city. Credit: Chip Clark, Smithsonian Institution.

DNA helps trace historic migrations

By studying patterns of genetic sharing between the St Mary’s individuals and over 11.5 million research participants in the 23andMe genetic database, the researchers were able to identify the likely places of origin for many of the colonial city’s earliest inhabitants.

The majority of these individuals share the strongest connection with participants from Great Britain, particularly in western England and Wales, while several appear genetically Irish.

Further, by examining patterns of sharing across the United States, they discovered a strong genetic signal that mirrored a documented migration of Catholics from Maryland to Kentucky that primarily occurred between 1780 and 1820, driven by economic pressures and anti-Catholic bias in Maryland.

Éadaoin Harney, senior scientist, population genetics research and development at 23andMe Research Institute, said: “Detecting such a clear genetic signal of this documented historical migration to Kentucky highlights the power of our approach.”

Identification of the second governor?

By focusing on research participants who shared the strongest genetic connections to the St Mary’s individuals, and inviting them to share details of their family histories, the research team tackled a novel problem; identifying otherwise unknown individuals by harnessing their genetic connections to living people. 

Focusing on the burials of three related individuals identified at the site, researchers collected genealogical information from study participants who shared the strongest genetic connections to these individuals.

By searching for overlaps in their family trees and integrating other anthropological information, the research team concluded that the most probable candidates for the identities of these individuals are Governor Thomas Greene (1609-1651), second governor of the colony of Maryland, his first wife Anne, and their son, Leonard. 

Harney said: “This is the first time that ancient DNA has been used to help identify unknown individuals, without any prior knowledge of who they might have been.

“And it just so happens that one of those individuals turned out to be one of colonial Maryland’s most prominent figures.”

Henry Miller, senior research fellow at Historic St Mary’s City, said: “We didn’t go into this study searching for Thomas Greene, but when the genetics team brought this name to me, it was remarkable how well the historical and archaeological records supported this potential identification.

“There is more work to be done to confirm his identity, but this genetic analysis was the key we needed to unlock this finding.”  

Reich added: “The possibilities that this kind of approach holds for enabling future reidentifications of historical individuals are truly exciting.”

The study is published in Current Biology.