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Genetic analysis has shed light on a long-standing mystery surrounding the fate of President George Washington’s younger brother Samuel and his relatives. Two of Samuel’s descendants and their mother were identified from skeletal remains found in unmarked burials dating back to the 1880s. The investigation also provided the first patrilineal DNA map for the first US president, who had no children of his own.
Researchers revealed key ancestry data through several types of DNA analysis, including a new technique that analyzed thousands of points of genomic data called single nucleotide polymorphisms, or SNPs, which are variations in the genetic sequence affecting a single nucleotide, building block of DNA.
DNA was another key component of Samuel Washington’s living descendants. By comparing the DNA of the pristine offspring with degraded, centuries-old DNA in bone fragments, the scientists discovered clues to long-lost identities and connections in the Washington family, researchers reported Thursday in the journal iScience.
“These multiple methods have enabled us to reveal relationships between unidentified human remains from the mid-19th century and living descendants who were separated from their ancestors by generations,” said senior study author Charla Marshall, a molecular and social anthropologist. -director of the Institute. US Department of Defense DNA Operations, in email.
These techniques could also help identify unknown remains from people who served in the military, dating as far back as World War II, according to the study.
Buried in unmarked graves
Samuel Washington, more than two years younger than George, died in 1781 and was buried in the cemetery at his Harewood estate near Charles Town, West Virginia. Records showed there were 20 members of the Washington family in Harewood cemetery, “including Samuel Washington and two of his wives, their children, grandchildren and great-grandchildren, among others,” said lead study author Courtney L. Cavagnino, a research scientist with the US 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 it from grave robbers, Cavagnino told CNN in an email. Other graves also lacked headstones, leaving modern historians unable to determine who was buried.
Researchers excavated five unmarked graves in the cemetery in 1999 in an attempt to locate Samuel Washington’s resting place. They recovered bones and small teeth from three burials, but DNA testing was inconclusive at the time, and the samples were badly degraded and contaminated with bacteria.
Fortunately for the authors of the new study, “DNA analysis has come a long way since the early 2000s,” Cavagnino said. They combined techniques that took full advantage of the shortened strands of damaged DNA from the remains, allowing them to extract the genetic material they needed. Maternal relationships were determined by mitochondrial DNA sequencing, and paternal relationships were discovered by looking at the Y chromosome. Additional data came from 95,000 SNPs, a huge amount of data that focuses on autosomal DNA (DNA not linked to sex chromosomes).
Genetic data first discovered that the remains were of a woman and her two sons; records also clarified that the wife was Lucinda “Lucy” Payne, and the males were Samuel’s grandson (and George’s grandson): George Steptoe Washington Jr. and Dr. Samuel Walter Washington. The DNA of the living offspring was closer to Dr. Samuel Walter Washington.
Not only did this data show that the deceased doctor was Washington’s living great-grandfather, it also showed which of the surviving brothers was still there, which would otherwise have been impossible to establish with certainty, the scientists said.
Retrieved ID
In 1882, the remains of several people were disinterred from Harewood and moved to graves at Zion Episcopal Church in Charlestown. Among them were Lucy Payne and her sons. But some of his bones were left behind; by the time the 1999 excavation recovered them, it was not clear who they belonged to. Now, nearly 150 years later, the identities of those remains have finally been determined.
“The combination of dead relatives and living relatives made this study a great puzzle, where you had to work hard to figure it out but you had all the necessary pieces,” said Connie J. Mulligan, professor in the Department of Anthropology and University Coordinator. the Genetics and Genomics Graduate Program at the University of Florida. Mulligan, who studies genetic variation to understand how DNA shapes health and disease, was not involved in the research.
The living descendant, Samuel Walter Washington, who is the current owner of the Harewood estate, managed to have more DNA in common with the two deceased brothers than the researchers expected. They attributed this to pedigree collapse – when marriages between relatives shorten the number of ancestors – caused by multiple cross-cousin marriages in the Washington family tree.
“The cross-cousin marriages only affected the siblings’ relationship and not their mother’s, who married into the family,” Mulligan told CNN. “I don’t know of any study that had a data set as cool as this one, with the complexity in the pedigree so that you could use empirical data to test how the interrelatedness changed the estimates of relatedness.” She added, “the study was a combination of cutting-edge science and great detective work!”
The researchers’ analysis also produced the first Y-chromosomal DNA profile for George Washington, because the male subjects 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,” the study authors wrote.
But while the results offer many new insights, the question that launched the 1999 dig remains: Where is George’s brother buried? Samuel’s grave has not yet been found, and none of his remains have been identified, according to Marshall. At this point, she said, he could lose his place entirely.
“The search for Samuel Washington’s grave is no longer underway,” Marshall said. “Her grave may have been exhumed long ago, and may never be found again.”
Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.
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