Genetic analysis has shed light on a long-standing mystery surrounding the fate of US President George Washington’s younger brother, Samuel, and his relatives. Two of Samuel and his mother’s descendants were recently identified from skeletal remains found in anonymous burials dating to the 1880s. The research also provided the first patrilineal DNA map of the first US president, who had no children. own.
Researchers identified key details of ancestry through 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 that They affect a single nucleotide, a basic component of DNA.
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 discovered clues to 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 who was several generations removed from their ancestors,” said the study’s lead author, Charla Marshall, a molecular anthropologist and deputy director of the Operations Department. of DNA from the US Department of Defense, in an email.
According to the study, these techniques could also help identify unknown remains of people who served in the military, dating back to World War II.
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 that Harewood Cemetery was home to 20 members of the Washington family, “including Samuel Washington and two of his wives, their children, grandchildren and great-grandchildren, among others,” said the study’s lead author, Courtney L. Cavagnino. research scientist at 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 excavated five unmarked graves at the cemetery in 1999 in an effort to find the resting place of Samuel Washington. They recovered small bones and teeth from three burials, but DNA testing at the time was inconclusive, as the samples were heavily 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 optimized the shortened strands of damaged DNA from the remains, allowing them to extract the genetic material they needed. Maternal relationships were determined by sequencing mitochondrial DNA, while paternal relationships were found by looking at Y chromosomes. More details came from 95,000 SNPs, a huge volume of data targeting autosomal DNA (DNA that is not attached to sex chromosomes). ).
Genetic data first established that the remains were a woman and her two children; The records further clarified that the woman was Lucinda “Lucy” Payne, and the men were Samuel’s grandsons (and George’s great-nephews): George Steptoe Washington Jr. and Dr. Samuel Walter Washington. The DNA of the living descendant was most similar to that of Dr. Samuel Walter Washington.
This data not only established that the deceased doctor was the living Washington’s great-great-grandfather, but also showed which remains belonged to which brother, which would otherwise have been impossible to establish with certainty, the scientists said.
Samuel Washington, George Washington’s younger brother, was buried in an unmarked grave in the cemetery of his Harewood estate (an interior view is pictured above) near Charles Town, West Virginia. (Frances Benjamin Johnson/Library of Congress via CNN Newsource)
Recovered identities
In 1882, the remains of several people were disinterred from Harewood and moved to graves at Zion Episcopal Church in Charles Town. Among them were Lucy Payne and her children. But some of her bones were left behind; When the 1999 excavation recovered them, it was unclear who they belonged to. Now, almost 150 years later, the identities of those remains have finally been resolved.
“The combination of deceased and living relatives made this study a wonderful puzzle, where you had to work hard to solve it, but it had all the necessary pieces,” he said Connie J. Mulligan, professor in the department of anthropology and coordinator of the Graduate Program in Genetics and Genomics 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, 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 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 affected only the siblings’ kinship relationships and not those of their mother, who married into the family,” Mulligan told CNN. “I don’t know of any study that has had as interesting a data set as this, with the complexity of the pedigree to be able to use empirical data to test how interrelatedness changed relatedness estimates.” The study, he added, “was a combination of cutting-edge science and great detective work!”
The researchers’ analysis also produced the first Y chromosome DNA profile of George Washington, as the male individuals in the study (living and deceased) “were all direct paternal descendants of Augustine Washington, George Washington’s father,” he said. Marshall. This profile could clarify genealogical relationships among people who inherited the Washington surname but are unsure of their family connections “to determine who is paternally related to George Washington himself,” the study authors wrote.
But while the finds offer many new insights, the question that started the 1999 dig remains: Where is George’s brother buried? According to Marshall, Samuel’s tomb has not yet been discovered nor have any of his remains been identified. At this point, he added, his whereabouts could 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 magazines.