Background

The Transatlantic Slave Trade stands as a defining tragedy of forced migration in human history. From the 15th to the 19th centuries, tens of millions of Africans were forcibly transported to the Americas. After Britain legally abolished the slave trade in 1807, the British Navy began intercepting illegal slave ships off the west coast of Africa. In this process, approximately 27,000 Africans were rescued and transported to the remote island of St. Helena in the South Atlantic. Officially designated as 'Liberated Africans,' they were in deplorable health due to the extreme overcrowding and unsanitary conditions aboard the slave ships. Shortly after arriving on the island, about 8,000 died, and their bodies were buried in a mass grave in Rupert's Valley.

Their tragedy was brought back into the spotlight in 2007 when a large number of remains were discovered during preliminary archaeological excavations for the construction of the island's airport. Existing historical research has primarily relied on ship records and customs logs from slave traders. These documentary sources have limitations in clearly identifying the origins or capture routes of the enslaved Africans. Most records only indicate the coastal ports from which they were taken. Consequently, the actual inland migration routes within the African continent from which the forced enslavement began, and their precise geographic origins, have long remained shrouded in mystery.

Key Findings

An international research team established a new, multifaceted analytical approach that integrates biochemical traces and genetic information from the remains. The researchers extracted Ancient DNA (aDNA) from the remains buried on St. Helena and reconstructed the entire genome sequence. This genetic information was compared against a database of modern African populations and various tribes. The analysis revealed that the genetic composition of the remains was closely related to modern populations in western Angola and Gabon. This serves as direct genetic evidence that they were primarily captured from the west-central African region.

At the same time, the researchers conducted strontium isotope analysis on the dental crowns of the remains. Strontium is absorbed into bones and teeth through food and water during childhood. Because the strontium isotope ratio (87Sr/86Sr) varies depending on the age and type of geological bedrock in each region, measuring this ratio can help infer the geographic location where childhood was spent. The results of the tooth analysis were surprising. The majority of the remains did not match the geological characteristics of the coastal area but rather reflected a geological profile from deep within the African continent. This indicates that they were not captured near the coast but were taken from inland and transported hundreds of kilometers to the coast.

Furthermore, the sex determination of 20 individuals revealed that 17 were male. This skewed sex ratio is closely related to the changing demand in the slave trade during the mid-to-late 19th century. At that time, plantation owners in the Americas, particularly those cultivating sugarcane and cotton, focused on purchasing young men who could perform heavy labor. The sex ratio of the St. Helena remains is interpreted as a reflection of this historical market demand. Some tooth analyses also revealed biochemical traces indicating that they had already moved to a different location several years before traveling to the coast, suggesting that they underwent a multi-stage forced migration process before boarding the slave ship.

Significance and Prospects

This research is significant in that it reconstructs the lives of enslaved people not recorded in historical documents using advanced scientific technology. It demonstrates the powerful utility of bioarchaeology, which combines genomics and biochemical analysis to supplement the gaps and biases in documentary records. By scientifically revealing the individual migration histories and roots of Africans who were buried anonymously, it contributes to clarifying historical injustices.

However, research challenges remain for precise analysis. The geological strontium map of the entire African continent and the modern and past genomic reference databases are not yet sufficient. This makes it technically difficult to pinpoint the exact hometown of a specific individual. Extracting high-quality aDNA from bones that have been buried in the soil for a long time is also a challenging obstacle. In the future, as environmental isotope data from various regions of Africa are accumulated, a more refined map is expected to be completed.