Mixed Race Studies

Deconstructing Jaco: Genetic Heritage of an Afrikaner

Annals of Human Genetics
Volume 71, Issue 5 (September 2007)
pages 674–688
DOI: 10.1111/j.1469-1809.2007.00363.x

J. M. Greeff, Professor of Genetics
University of Pretoria

It is often assumed that Afrikaners stem from a small number of Dutch immigrants. As a result they should be genetically homogeneous, show founder effects and be rather inbred. By disentangling my own South African pedigree, that is on average 12 generations deep, I try to quantify the genetic heritage of an Afrikaner. As much as 6% of my genes have been contributed by slaves from Africa, Madagascar and India, and a woman from China. This figure compares well to other genetic and genealogical estimates. Seventy three percent of my lineages coalesce into common founders, and I am related in excess of 10 times to 20 founder ancestors (30 times to Willem Schalk van der Merwe). Significant founder effects are thus possible. The overrepresentation of certain founder ancestors is in part explained by the fact that they had more children. This is remarkable given that they lived more than 300 years (or 12 generations) ago. DECONSTRUCT, a new program for pedigree analysis, identified 125 common ancestors in my pedigree. However, these common ancestors are so distant from myself, paths of between 16 and 25 steps in length, that my inbreeding coefficient is not unusually high (f≈0.0019).

Introduction

‘After three centuries of evolution the population structure of the Afrikaners is still far from stable, and there does not appear to be much prospect of its ever attaining uniformity… The numerous and often mutually contradictory genetic statements frequently made about them can consequently all be simultaneously true. The Afrikaner is a product of miscegenation, the last ‘pure European’, pathologically inbred and a manifestation of hybrid vigour, all at the same time.’ (Nurse et al. 1985)

Afrikaners are often considered a rather homogeneous, probably rather inbred, white population of Dutch ancestry. Yet, as the above quotation illustrates, there are uncertainties about the genetic composition of Afrikaners. Due to Afrikaners’ high linkage disequilibrium, they are seen as a fruitful hunting ground for genes associated with disease (Hall et al. 2002). It is thus important that we have a clear appreciation of the Afrikaners’ genetic heritage. In what follows I address the questions of racial admixture, nationalities, founder effects and inbreeding in the Afrikaner. I do so in a novel way: rather than taking a sample of modern Afrikaners and genotyping them, I start with one living Afrikaner and trace most of his South African ancestors. In this way I cast a net into his past and hope to get an impression of what the genetic heritage of a typical Afrikaner may be…

…Given that genealogists could show that as much as 7% of Afrikaner genetic heritage is not of European descent (Heese, 1971), I find it curious that a system such as apartheid worked in South Africa. Seven percent is not a trivial amount, and is equivalent to having slightly more than a great-great-grandparent who was non-European. Since most of this non-European genetic heritage came into the Afrikaner population via female slaves, one would expect that as much as 14% of Afrikaner mitochondrial DNA is not even European. This female bias influx stems from the fact that emigrants were predominantly male, resulting in a male biased sex ratio of adults (Gouws, 1981).

Similarly, genetic studies also give support for this mixed racial ancestry. Working with a number of blood group gene frequencies, Botha & Pritchard (1972) estimated that beween 6–7% admixture between western European and slaves from Africa and the East, and/or Khoikhoi, would be required to explain the allele frequencies. Nurse et al. (1985) listed a number of alleles typical to the Khoisan and Bantu-speaking peoples that are found in low frequencies in Afrikaners (ABO system: A^bantu; glucose-6-phosphate dehydrogenase: Gd^A- and Gd^A; Rhesus: Rº; Haemoglobin C)…

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