GENETIC ANCESTRY TESTS are a popular product for consumption in the USA. Deborah Bolnick and her associates (Bolnick et al. 2007: 399) estimate that there have been over 460 000 consumers of these tests in the first six years of this century. More than two dozen companies marketing this product contribute to growing consumer interest in such tests. African-Americans in search of a ‘homeland’, and Americans who hope to obtain or contest Native American ‘tribal’ affiliations, take them mainly to validate or explore their social identification. Alondra Nelson's qualitative study in the USA and the UK demonstrates that tests are effective when they offer a ‘usable past’ constructed from ‘strategic’ alignment of results with individual life histories (Nelson 2008: 763, 767, my emphasis).

In South Africa, DNA samples and genetic ancestry tests are used mainly in collaborative historical work by human population geneticists, evolutionary biologists, anthropologists and palaeontologists. Part of this work comes in the wake of the Human Genome Diversity Project (HGDP) established in 1991. Its objective is to trace human variation in DNA in order to reconstruct the origins and migratory patterns of humankind and to understand the biological relationships between people considered to be of different groups. The HGDP emphasises research on ‘indigenous peoples’, with the Khoi-San of South Africa leading the ‘index of indigeneity’. The geneticist Luca Cavalli-Sforza and his associates note that lest the opportunity to preserve the historic record of the diversity of human genetic heritage be ‘irretrievably lost’, it is important to collect DNA samples from ‘isolated human populations’ because these ‘can tell us the most about our evolutionary past’ (Cavalli-Sforza et al. 1991: 490).