NEW YORK – An international team has turned to ancient DNA profiling to understand the origins of "liberated" Africans buried on the remote tropical island of St. Helena in the British Overseas Territory in the South Atlantic, a site linked to the suppression of the transatlantic slave trade. The findings appeared in the American Journal of Human Genetics on Thursday.
"This project was part of a larger ongoing effort by many people on and off the island to try and restore knowledge of St. Helena’s liberated Africans," coauthor Helena Bennett, with the St Helena National Trust, said in a statement. "We hope that by telling their story we can honor their legacy and ensure that their lives and fates are not forgotten."
Past research has shown that around 27,000 African individuals on slave ships headed to the Americas were rescued by the British Royal Navy from 1840 to 1867, during a transatlantic slave trade that spanned the 16th to 19th centuries and involved more than 12.5 million individuals abducted from Africa.
"Our research demonstrates how ancient DNA analyses can be used to help restore knowledge of the lives and experiences of enslaved and other marginalized individuals or groups whose stories have been largely omitted from written records," first author Marcela Sandoval-Velasco, a postdoctoral researcher with the Smithsonian Institution's National Museum of Natural History, said in an email, noting that such genetic analyses also provide a look at the genealogical relationships between liberated individuals on St. Helena and present-day individuals in Africa, the Americas, and beyond.
After searching for high-quality ancient DNA in samples from 63 individuals excavated from a Rupert's Valley burial site in 2007 and 2008, researchers at the University of Copenhagen, Amgen's Decode Genetics, the University of Iceland, and other international centers performed shallow shotgun sequencing and whole-genome capture enrichment sequencing on samples representing 20 of the ancient individuals.
The burial site, which included 325 individuals and 178 graves, was excavated during roadwork done in preparation for airport construction on the island, the team explained. Archaeological work done at that time linked the gravesites to Africans liberated from slave ships, providing an opportunity to better understand the geographic origins of these individuals.
"[G]enomic information represents a new source of historical information or historical record," Sandoval-Velasco said. "Specifically, through molecular analyses, and particularly ancient DNA (or paleogenomic) techniques, it was possible to reconstruct and narrow down the range of possible source populations within Africa."
Together with genotyping data for more than 3,000 individuals from dozens of modern-day populations in sub-Saharan Africa, the team's analysis indicated that the liberated Africans brought to St. Helena largely had ancestry related to populations in northern Angola and Gabon.
"This information adds to our understanding of this community and helps us to tell their story," said co-corresponding author Schroeder, a researcher at the University of Copenhagen, in an email.
Consistent with transatlantic slave trade patterns documented in the past, the investigators found that all but three of the 20 ancient individuals profiled were male. Among the other samples screened for high-quality DNA, 32 individuals were male and just 16 were female. The remaining 15 individuals were sub-adults that could not be classified as male or female based on their skeletal traits.
"[O]n one level, our study illustrates how ancient DNA analyses can be used to recover long-lost aspects of the lives and experiences of enslaved and other marginalized communities whose stories have been largely forgotten," Schroeder noted.
"But on another level," he added, "I think it also serves to highlight the fate of the 27,000 liberated Africans who were brought to St Helena during the last phase of the transatlantic slave trade. It's a less well-known story that deserves to be told."
For her part, Sandoval-Velasco emphasized that future efforts to analyze additional ancient genomes in combination with historical clues, ethnographic insights, and reference datasets "could bolster knowledge about the whereabouts of different groups in those historical times and help recover long-lost aspects of the lives and experiences of enslaved individuals whose stories have been largely forgotten."