DNA analysis from unmarked graves reveals George Washington’s family secrets

The researchers determined key details of George Washington’s ancestry using several types of DNA analysis, including a new technique that analyzed tens of thousands of genomic data points called single nucleotide polymorphisms, or SNPs, which are variations in the genetic sequence affecting just one nucleotide, the building block of DNA.

As CNN notes, another key component was DNA from a living descendant of Samuel Washington. By comparing the descendant’s pristine DNA with centuries-old degraded DNA in bone fragments, scientists found clues about long-lost identities and connections in the Washington family, researchers reported Thursday in the journal iScience.

“A variety of these methods allowed us to identify relationships between unidentified human remains from the mid-19th century and a living descendant who was several generations removed from their ancestors,” said senior study author Charla Marshall, a molecular anthropologist and deputy director of the department’s DNA Operations Division. US defense.

According to the study, these methods can also help identify unknown remains of people who served in the military dating back to World War II.

Samuel Washington, more than two years younger than George, died in 1781 and was buried in the cemetery at his Harwood estate near Charles Town, West Virginia. Records showed that 20 members of the Washington family are buried at Harewood Cemetery, “including Samuel Washington and his two wives, their children, grandchildren and great-grandchildren, among others,” said lead study author Courtney L. Cavagnino, a medical examiner system scientist. Armed Forces DNA Identification Laboratory.

But unlike George Washington, who is buried in a magnificent marble tomb in Mount Vernon, Virginia, Samuel’s grave was unmarked, likely to protect against grave robbers, Cavagnino reports. Other graves also lacked headstones, making it difficult for modern historians to say for sure who was buried where.

In 1999, researchers excavated five unmarked graves in the cemetery in an attempt to find the resting place of Samuel Washington. They recovered small bones and teeth from three burials, but DNA analysis at the time was inconclusive: the samples were badly degraded and contaminated with bacteria.

Fortunately for the authors of the new study, “DNA testing has come a long way since the early 2000s,” says Cavagnino. The researchers combined techniques that optimized shortened strands of damaged DNA from the remains, allowing them to extract the necessary genetic material. Maternal relatedness was determined by sequencing mitochondrial DNA, while paternal relatedness was discovered by studying Y chromosomes. Additional details come from 95,000 SNPs, a huge amount of data targeting autosomal DNA (DNA that is not attached to the sex chromosomes).

For the first time, genetic evidence has determined that the remains belonged to a woman and her two sons; the records further clarified that the woman’s name was Lucinda “Lucy” Payne, and the men were Samuel’s grandchildren (and George’s great-nephews): George Steptoe Washington, Jr. and Dr. Samuel Walter Washington. The living descendant’s DNA was closer to that of Dr. Samuel Walter Washington.

The findings not only established that the deceased doctor was the living Washington’s great-great-grandfather, the scientists said, but also revealed which remains belonged to which brother, something that would otherwise have been impossible to establish with certainty.

In 1882, the remains of several people were removed from Harwood and transferred to graves at Zion Episcopal Church in Charles Town. Among them were Lucy Payne and her sons. But some of their bones were left behind; by the time excavations in 1999 uncovered them, it was unclear who they belonged to. Now, almost 150 years later, the identity of these remains has finally been established.

“The combination of deceased and living relatives made this study a wonderful puzzle where you had to work hard to figure it out, but you had all the pieces you needed,” said Connie J. Mulligan, professor in the Department of Anthropology and coordinator of the Genetics and Genomics Graduate Program at the University of Florida.

A living descendant, Samuel Walter Washington, who is the current owner of the Harewood estate, has more DNA in common with the two deceased brothers than researchers expected. Scientists attributed this to pedigree collapse—when marriages between relatives reduce the number of ancestors—caused by numerous marriages between first cousins ​​in Washington’s family tree.

“Marriages between first cousins ​​only affected the brothers’ sibling relationships, not their mother, who married into the family,” Mulligan tells CNN. “I don’t know of any studies that have a dataset as cool as this one, with the complexity of the ancestry so that you can use the empirical data to test how the relationship changed relatedness estimates.” The research, she added, “was a combination of cutting-edge science and great detective work!”

The researchers’ analysis also produced the first Y-chromosomal DNA profile of George Washington, since the men in the study — living and deceased — “were all direct paternal descendants of Augustine Washington, George Washington’s father,” Marshall said. This profile could clarify genealogical relationships among people who inherited the Washington surname but are unsure of their family ties, “to determine who is related to George Washington himself on the paternal side,” the study authors write.

But while the findings provide many new insights, the question that prompted the 1999 excavation remains open: where is George’s brother buried? Samuel’s grave has yet to be discovered, and none of his remains have been identified, according to Marshall. At this point, she added, his whereabouts may be lost forever.

“The search for Samuel Washington’s grave is no longer ongoing,” Marshall said. “Perhaps his grave was exhumed a long time ago and may never be found again.”