Tooth Chemistry Unveils St. Helena's African Origins

The remains of Africans liberated from illegal slave ships and buried on the island of St. Helena are providing new insight into the population history of the transatlantic slave trade. By combining chemical signatures preserved in teeth with ancient DNA and historical records, a new study reconstructs the geographic origins and early-life movements of these individuals. The findings also inform local discussions about remembrance and repatriation. The transatlantic slave trade forcibly displaced more than 12.5 million Africans, yet the specific origins and journeys of many individuals remain poorly understood. After the British abolished the slave trade in 1807, the Royal Navy intercepted illegal slave ships and brought many of the liberated Africans to the island of St. Helena. However, nearly a third of those brought to the island died shortly after landing due to malnutrition and disease. Their remains were rediscovered during archaeological excavations in 2007–2008, prompting a community-led effort to better understand and commemorate their lives. To enrich the understanding of this population, Xueye Wang and colleagues analyzed strontium isotope (⁸⁷Sr/⁸⁶Sr) signatures from the teeth of 152 liberated Africans buried on St. Helena, combining these results with ancient DNA and historical records to better reconstruct their geographic origins. Because tooth enamel preserves chemical traces of the geological environment where a person grew up, these isotopes can provide clues about childhood homelands and migration histories. Wang et al. found that these individuals originated from a wide geographic area extending from coastal western Central Africa to regions much farther inland, including locations in modern-day Angola, Zimbabwe, and other parts of southern Africa. What's more, the authors found direct evidence that some enslaved Africans may have been forcibly relocated years before embarking on transatlantic slave ships. While most individuals remained in the same region during childhood, others showed chemical signatures indicating movement, often toward the coastal slave-trading ports, including one case in which a child appears to have been moved between the ages of seven and nine. Wang et al. note that combining strontium isotope analysis with genetic and historical evidence can more precisely identify the likely homelands of people displaced by the transatlantic slave trade, providing valuable information for discussions about the repatriation of human remains. However, the findings also underscore the complexity of such decisions, as many individuals likely originated from widely separated regions. Rather than prescribing where remains should be reburied, the authors argue that scientific evidence can support informed, community-led decisions about commemoration, remembrance, and, where appropriate, repatriation. In a related Perspective, R. Alexander Bentley discusses the findings in greater detail.