The history of Amandelboom, now Williston, in the Northern Cape does not easily lend itself to a straightforward heritage narrative of victims and villains. Instead, it is a complicated story that raises all sorts of troubling questions and ethical challenges.

During one of my first visits to the small Karoo town of Williston, Elsa van Schalkwyk, the local town historian, alerted me to a forgotten history of the Northern Cape frontier involving the "Basters" of mixed Khoi and European ancestry who lived at the German Rhenish mission in Amandelboom (renamed Williston in 1883) for much of the 19th century. The Amandelboom Basters were a prosperous and independent livestock-owning community who were pushed off their land in the late 1860s and decided to trek more than 1,000km northwards to Rehoboth in what is now Namibia.

While doing research for my book Letters of Stone I made the startling discovery that in 1908, the year the Nama and Herero genocide ended, the Rehoboth Baster community had been measured and photographed by the German physical anthropologist Eugen Fischer, who later became Hitler's most senior racial scientist.

Fischer's career as a leading international eugenics scientist soared after he published his ethnography on the Rehoboth Basters in 1913. From 1928 to 1942, Fischer was the director of Berlin's notorious Kaiser Wilhelm Institute for Anthropology, Human Heredity and Eugenics. During World War 2 the Institute had received eye specimens and blood samples from Auschwitz from one...