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Genetic analysis has shed light on a long-standing mystery surrounding the president’s fate George Washington‘s younger brother Samuel and his relatives. Two of Samuel’s descendants and their mother were recently identified from skeletal remains found in unmarked burials dating back to the 1880s. The research also produced the first patrilineal DNA map for the first US president, who had no children of his own.
Researchers have mapped out important details about the ancestry through several types of DNA analysis, including a new technique that analyzed tens of thousands of points of genomic data called single nucleotide polymorphisms, or SNPs. These are variations in the genetic sequence that affect only one nucleotide, a building block of DNA. DNA.
Another important component was DNA from a living descendant of Samuel Washington. By comparing the descendant’s pristine DNA with degraded, ancient DNA in bone fragments, the scientists uncovered clues about long-lost identities and connections in the Washington family, researchers reported Thursday in the journal iScience.
“The multitude of these methods allowed us to reveal relationships between unidentified human remains from the mid-19th century and a living descendant several generations removed from its ancestors,” said senior study author Charla Marshall, a molecular anthropologist and adjunct director of U.S. Department of Defense DNA operations, in an email.
These techniques could also help identify unknown remains of people who served in the military dating back to 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 on his Harewood estate near Charles Town, West Virginia. Records showed that Harewood Cemetery was home to 20 members of the Washington family, “including Samuel Washington and two of his wives, including their children, grandchildren and great-grandchildren,” said lead author Courtney L. Cavagnino, a researcher at the DNA Institute. US Armed Forces identification laboratory.
But unlike George Washington, who is buried in a beautiful marble grave in Mount Vernon, Virginia, Samuel’s grave was unmarked, likely to protect it from grave robbers, Cavagnino told CNN in an email. Other graves were also missing headstones, leaving modern historians unsure of who was buried where.
Researchers excavated five unmarked graves in the cemetery in 1999 in an attempt to find Samuel Washington’s resting place. They found small bones and teeth from three burials, but DNA testing at the time was inconclusive because the samples were severely decomposed 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 optimized the shortened strands of damaged DNA from the remains, allowing them to extract the genetic material they needed. Maternal relationships were determined through mitochondrial DNA sequencing, while paternal relationships were found by looking at Y chromosomes. Further details came from 95,000 SNPs, a huge amount of data focused on autosomal DNA (DNA not attached to sex chromosomes).
Genetic data first showed that the remains were a woman and her two sons; records further revealed that the woman was Lucinda “Lucy” Payne, and that the men were Samuel’s grandsons (and George’s second cousins): George Steptoe Washington Jr. and dr. Samuel Walter Washington. The living descendant’s DNA was a closer match to Dr. Samuel Walter Washington.
These records not only showed that the deceased doctor was Washington’s living great-great-grandfather, but also which remains belonged to which brother, which otherwise would have been impossible to determine with certainty, the scientists said.
Recovered identities
By 1882, the remains of several people from Harewood had been exhumed 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 the 1999 dig found 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 research a beautiful puzzle that you had to work hard to solve, but you had all the necessary pieces,” said Connie J. Mulligan, professor in the Department of Anthropology and coordinator of the Genetics and Genomics Graduate Program at the University of Florida. Mulligan, who studies genetic variations to understand how DNA affects health and disease, was not involved in the research.
The living descendant, Samuel Walter Washington, the current owner of the Harewood estate, turned out to have more DNA in common with the two deceased brothers than researchers expected. They attributed this to family tree collapse – when marriages between relatives shorten the number of ancestors – caused by multiple marriages between cousins in Washington’s family tree.
“The marriages between cousins only affected the kinship relationships of the brothers and not that of their mother, who married into the family,” Mulligan told CNN. “I don’t know of any study with a data set as cool as this, with the complexity of the family tree, so you could use empirical data to test how interconnectedness changed estimates of kinship.” The research, she added, “was a combination of groundbreaking science and great detective work!”
The researchers’ analysis also produced the first Y-chromosomal DNA profile for George Washington, as male individuals in the study — living and deceased — “were all direct paternal descendants of Augustine Washington, George Washington’s father,” Marshall said . This profile could illuminate genealogical relationships among people who have inherited the Washington surname but are uncertain about their familial connections “to determine who is paternally related to George Washington himself,” the study authors wrote.
But while the findings provide many new insights, the question that sparked the 1999 dig remains: where is George’s brother buried? According to Marshall, Samuel’s grave has not yet been discovered, nor have his remains been identified. At this point, she added, his whereabouts may be lost forever.
“The search for Samuel Washington’s grave is no longer ongoing,” Marshall said. “It is possible that his grave was dug up long ago and may never be found again.”
Mindy Weisberger is a science writer and media producer whose work has appeared in the magazines LiveScience, Scientific American, and How It Works.
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