WASHINGTON — A family portrait taken in a Charleston photography studio in 1899 has stunned historians and geneticists after a routine high-resolution scan revealed that the youngest child in the photograph had six fully formed fingers on his right hand — a detail that had gone unnoticed for 124 years.
The discovery, made in January 2023 by Dr. Rachel Foster of the National Museum of African American History and Culture, has since unraveled a multigenerational genetic mystery stretching from West Africa to a living orthopedic surgeon in Baltimore and his 7-year-old daughter.
The photograph, labeled “Thomas Family, Charleston, SC, 1899,” shows Thomas, a master carpenter, his wife Elizabeth, and their five children posed with the dignity and formality typical of studio portraiture of the era. It was donated to the museum in 1987 and had been admired for decades as evidence of Black prosperity in the post-Reconstruction South.
But it was not until Foster placed the image on a 4,800-dots-per-inch scanner that the truth emerged. As the scan resolved the child Samuel’s right hand, pixel by pixel, Foster saw what no one had seen before: six distinct, fully formed fingers, positioned beside the pinky.
“Oh my god,” Foster whispered, according to an account of the discovery. She zoomed in again and again. The extra digit was not a blur, not an artifact of light, but a clear anatomical feature — postaxial polydactyly.
Foster immediately contacted Dr. Marcus Webb, a geneticist at Johns Hopkins University specializing in hereditary conditions in African American populations. Within 48 hours, Webb was in Washington examining the scan.
“This is remarkable,” Webb said, noting that polydactyly occurs in roughly one in 1,000 births but is rarely captured so clearly in 19th-century photography — and almost never documented across so many generations.
What followed was months of painstaking research. Church records from Morris Street Baptist Church in Charleston revealed Samuel’s baptism in 1893, along with a notation describing him as “marked with his distinction, blessed be his maker’s hands.” A 1905 church newsletter referenced a family tradition of “the maker’s hands passed from father to son.”
The genealogical trail led from Charleston to Philadelphia, where Samuel’s brother Robert appeared in a 1948 city directory as a carpenter. From there, the researchers traced descendants through Pennsylvania, Maryland, New Jersey, and New York.
Then, three months into the investigation, Foster found a genealogy forum post from a man named David Clark, researching his Charleston ancestors named Thomas — and mentioning a family story about special hands.
David Clark, it turned out, was a 47-year-old orthopedic surgeon in Baltimore. He also had six fingers on his right hand. His grandfather had it.
His daughter Emma, born in 2016, has it too.
“My grandfather refused to let doctors remove it,” Clark said. “He said, ‘That hand is who we are. Don’t you dare cut away what God and blood gave him.’”
Genetic testing confirmed that the family’s polydactyly is caused by an exceptionally rare mutation in the GLI3 gene, which regulates limb development. Webb said fewer than 20 cases with this exact mutation have been documented worldwide.
The research team traced the trait back at least six confirmed generations — from Emma to Samuel in the 1890s — and, based on oral history and church records, possibly eight to 10 generations, placing its origin in the early 1800s, likely in West Africa.
“The GLI3 mutation likely originated in West Africa,” Webb said. “When your ancestor was enslaved and brought to America, he carried that gene. Because polydactyly is a dominant trait, it had a high probability of being passed to each generation.”
A worn leather journal kept by a 1920s Charleston wheelwright offered further confirmation. Its author wrote that the “gift goes back to Thomas’s father and his father before him, back to the old country before the chains.”
An 1887 anthropological text by a British colonial officer described a West African master carver with six digits on each hand who claimed the trait ran in his family line for generations and attributed his extraordinary skill to it.
The museum mounted a special exhibition, “Hands of Legacy: The Thomas Family Story,” in September 2023. The 1899 photograph is the centerpiece, displayed alongside high-resolution details of Samuel’s hand, genealogical charts, and genetic diagrams.
The exhibition has since become one of the museum’s most viewed exhibits. David Clark has received hundreds of messages from people with polydactyly, including a woman in Nigeria whose son has the same trait.
“For so long I thought our story was just about my family,” Clark said. “But it’s bigger. It’s about how difference can be strength.”
The academic paper co-authored by Foster, Webb, and Clark won the Journal of Medical Genetics Award for Excellence in Historical Genetics Research. In his acceptance speech, Clark spoke not of science but of visibility.
“Be visible. Be proud. Be exactly who you are,” he said, “because someone in the future might need to see you to understand themselves.”
Emma, now 7, recently wrote a letter to her great-great-great-grandfather Samuel. It sits framed on her father’s desk.
“Thank you for not hiding,” it reads. “Thank you for being in the picture so we could find you.”