Achi news desk-
Genetic analysis has shed light on a long-standing mystery surrounding the fate of US President George Washington’s younger brother Samuel and his family. Two of Samuel’s descendants and their mother were recently 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 president of the United States, who had no children of his own.
Researchers extracted key ancestry details 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, which are variations in the genetic sequence that affect a single nucleotide just a building block of DNA.
Another key element was the DNA of a living descendant of Samuel Washington. By comparing the descendant’s pristine DNA with degraded, centuries-old DNA in bone fragments, the scientists uncovered clues about lost identities and connections in the Washington family, researchers reported Thursday in the journal iScience.
“These many methods allowed us to uncover relationships between unknown human remains from the mid-19th century and a living descendant who was several generations removed from his ancestors,” said senior study author Charla Marshall, a molecular anthropologist and deputy director of the Institute. US Department of Defense DNA Operations, in email.
These techniques could also help identify unknown traces of people who served in the military, going 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 of his Harewood estate near Charles Town, West Virginia. Records showed the Harewood cemetery held 20 members of the Washington family, “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 unsure of who was buried where.
Researchers dug up five unmarked graves in the cemetery in 1999 in an effort to find Samuel Washington’s resting place. They recovered small bones and teeth from three burials, but DNA tests at the time were inconclusive, with the samples 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 made the most of the shorter strands of damaged DNA from the remains, allowing them to extract the genetic material they needed. Maternal relatives were determined by mitochondrial DNA sequencing, while paternal relatives were discovered by looking at Y chromosomes. Further details came from 95,000 SNPs, a huge amount of data targeting autosomal DNA (DNA not linked to sex chromosomes).
Genetic data first established that the remains were a woman and her two sons; records further explained that the wife was Lucinda “Lucy” Payne, and the males were Samuel’s (and George’s) grandsons: George Steptoe Washington Jr and Dr. Samuel Walter Washington. The living descendant’s DNA was a closer match to Dr. Samuel Walter Washington.
Not only did this data show that the deceased doctor was Washington’s living great-great-grandfather, it also showed which remains belonged to which brother, which would otherwise have been impossible to establish with certainty, he said. the scientists.
Samuel Washington, George Washington’s younger brother, was buried in an unmarked grave in the cemetery at his Harewood estate (pictured above has an interior view) near Charles Town, West Virginia. (Frank Benjamin Johnson/Library of Congress via CNN Newsource)
Identities restored
In 1882, the remains of a number of people were exhumed from Harewood and moved to graves in the 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 excavation recovered them, it was not clear who they belonged to. Now, almost 150 years later, the identity of those remains has finally been determined.
“The combination of deceased 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 anthropology department and coordinator of the Genetics and Genomics Graduate Program at the University of Florida. Mulligan, who studies genetic variations 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, turned out 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 kinship relationships of the brothers and not their mother, who married into the family,” Mulligan told CNN. “I don’t know of any study that has had a dataset as cool as this one, with the complexity in the pedigree so you could use empirical data to test how the correlation changed the estimates of kinship relatedness.” He added that the study, “is a combination of cutting-edge 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 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’s own father,” the study authors wrote.
But although the findings offer many new insights, the question that launched the 1999 excavation 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, he added, his whereabouts may be lost forever.
“The search for Samuel Washington’s grave is no longer underway,” Marshall said. “His 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.
