Genetics and Southern African Prehistory: an Archaeological View
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JASs Invited Reviews Journal of Anthropological Sciences Vol. 88 (2010), pp. 73-92 Genetics and southern African prehistory: an archaeological view Peter Mitchell School of Archaeology, University of Oxford; School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand e-mail: [email protected] Summary - Southern African populations speaking languages that are often - but inaccurately - grouped together under the label ‘Khoisan’ are an important focus of molecular genetic research, not least in tracking the early stages of human genetic diversification. This paper reviews these studies from an archaeological standpoint, concentrating on modern human origins, the introduction of pastoralism to southern Africa and admixture between the region’s indigenous foragers and incoming Bantu-speaking farmers. To minimise confusion and facilitate correlation with anthropological, linguistic and archaeological data it emphasises the need to use ethnolinguistic labels accurately and with due regard for the particular histories of individual groups. It also stresses the geographically and culturally biased nature of the genetic studies undertaken to date, which employ data from only a few ‘Khoisan’ groups. Specific topics for which the combined deployment of genetic and archaeological methods would be particularly useful include the early history of Ju-≠Hoan- and Tuu-speaking hunter-gatherers, the expansion of Khoe-speaking populations, the chronology of genetic exchange between hunter-gatherers and farmers, and the origins of the Sotho/Tswana- and Nguni-speaking populations that dominate much of southern Africa today. Keywords – Southern Africa, Genetics, ‘Khoisan’, Archaeology, Hunter-gatherers, Pastoralism, Sotho/ Tswana, Nguni. Introduction (mtDNA) and Y chromosome DNA lineages from the earliest stages of modern humans’ One of the most exciting developments in genetic diversification. Other research has anthropology over the last twenty years has been focused on their relationships with East African the growth of molecular genetics. From the ini- populations who also speak languages contain- tially startling, but now generally accepted, claim ing click sounds, one conclusion being the pos- that humankind has a geologically recent ances- sibility that a relatively recent movement of peo- try south of the Sahara to a myriad of applica- ple from East Africa contributed to the genesis tions tracking the movements and relationships of southern Africa’s Khoe-speaking pastoralists. of populations, analyses of the human genome Admixture between ‘Khoisan’ hunter-gatherers have made increasingly frequent contributions and herders and more recently arrived Bantu- to understanding the past. Contemporary south- speaking populations has also received attention. ern African populations speaking what are often Recent publication of the complete genomes of described as ‘Khoisan’ languages hold an impor- four San individuals from Namibia (Schuster et tant position in these developments as numerous al., 2010) will undoubtedly encourage research studies evidence their retention of mitochondrial across all these fronts. the JASs is published by the Istituto Italiano di Antropologia www.isita-org.com 74 Genetics and southern African prehistory In reading – and now writing about – the as a biological (physical anthropological) label issues I have just mentioned I am conscious of covering all southern Africa’s hunter-gatherer my own inadequacies on the biological front and and herder communities, it soon came to be make no pretence of being able to evaluate the employed as a collective term that also reflected specific protocols or methodologies employed shared features of both language and culture by geneticists. Summaries of some of the studies (Schapera, 1930). Today, it retains popularity as considered here are provided from a genetic stand- a general term for groups better differentiated as point by Tishkoff et al. (2007, 2009), Soodyall et Bushmen (or San; used here to refer to hunter- al. (2008), and Güldemann & Stoneking (2008). gatherer populations) or Khoe (earlier Khoi and No such survey has, however, yet emerged from - pejoratively - ‘Hottentots’) (Barnard, 1992; an archaeological background. It therefore seems Mitchell, 2002, pp.7-8). Despite a complete lack worthwhile to summarise for fellow archaeolo- of corroborating physical anthropological evi- gists the key findings of recent genetic studies, dence (Schepartz, 1998; Morris, 2003) or any- while simultaneously identifying for workers in thing other than the most superficial parallels in genetic history some of the difficulties that their stone tool industries (Barham & Mitchell, 2008), research raises for prehistorians. Such difficulties the term was also extended to East Africa where include lack of clarity as to the source of some of some populations (the Hadzabe and Sandawe of the DNA samples analysed, question marks over Tanzania) do indeed speak languages that use how far such samples are representative of all click sounds, just like the aboriginal herders and ‘Khoisan’ populations, the complete omission of foragers of southern Africa. Assuming that this archaeological data from some studies (e.g. Wood coincidence reflects a more profound linguis- et al., 2005) and the inappropriate citation by oth- tic association and shared ancestry, Greenberg ers of non-archaeological sources as authorities on (1963) and Ehret (1998) argued that Hadzane archaeological evidence (e.g. Nurse et al., 1985 (the language spoken by the Hadzabe), Sandawe in Semino et al., 2002, p.265; Cavalli-Sforza et and the many ‘Khoisan’ languages spoken now al., 1994 in Campbell & Tishkoff, 2008, p.407). or in the recent past in South Africa, Lesotho, Recognising that closer collaboration between Namibia, Botswana, Zimbabwe and Angola molecular genetics and archaeology should benefit constitute a single linguistic macro-family com- both disciplines, I also identify several questions of parable to the Kordofanian, Nilo-Saharan and archaeological concern for which molecular genet- Afroasiatic groupings that are also indigenous to ics may be able to offer help and guidance. Those Africa (Blench, 2006). This interpretation con- seeking more detail on the southern African tinues to be reflected in some recent syntheses in archaeological sequence should consult Mitchell which language serves as a proxy for ethnic affili- (2002) and the more recent surveys of Huffman ation and constitutes a framework against which (2007; Iron Age farming communities), Barham genetic data are analysed (e.g. Cavalli-Sforza, & Mitchell (2008; hunter-gatherer and earlier 2001; Wood et al., 2005; Tishkoff et al., 2009). hominin research), Lombard et al. (2008; the There are two problems with this approach. Middle Stone Age) and Sadr & Fauvelle-Aymar First, as MacEachern (2000) has emphasised in a (2008; early herders). much more wide-ranging analysis, no one-to-one fixed relationships are likely to exist, or to have existed, between language and ethnicity in Africa What’s in a name? The diversity of or elsewhere. The assumption that they do may the ‘Khoisan’ be a useful first step, but it needs to be treated with appropriate caution and, wherever possible, Thus far I have been careful to place the questioned and tested against other data for, as word ‘Khoisan’ in quotation marks and there is Smith (2006) reminds us, many contemporary good reason for this. Invented by Schulze (1926) ‘identities’ have demonstrably recent origins. P. Mitchell 75 Second, and more specifically, ‘Khoisan’s’ own in eastern Botswana) and Kwadi (extinct and validity as an analytical unit is extremely weak, known only from limited field notes but once in part because all but a tiny minority of linguists spoken in southern Angola) has been uncertain conclude that Hadzane has no demonstrable (Crawhall, 2006a, p.114). However, Güldemann connection to any other language (Sands, 1998; (2008) presents a strong case for linking Kwadi Güldemann & Vossen, 2000; Blench, 2006; with Khoe, while ≠Hoã affiliates with Ju into Güldemann & Stoneking, 2008; König, 2008; what may more properly be called the Ju-≠Hoã cf. Ehret, 1998; Honken, 1998). or Ju-≠Hoan family (Güldemann, 2003, 2008). Within southern Africa the shared presence Other languages certainly once existed, among of clicks may reflect inheritance from some com- them those spoken by the foraging ‘Sonqua’ mon language(s), but any such derivation lies so encountered by seventeenth century Dutch far in the past as to be beyond the reach of cur- explorers in the mountains north of Cape Town rent linguistic analysis. Instead, three completely and those belonging to the hunter-gatherers who isolated families are discernible and no genea- inhabited the eastern third of southern Africa logical relationship is demonstrable between them before their assimilation/displacement by Bantu- (Güldemann & Stoneking, 2008; König, 2008). speaking farmers in the first and second millen- These families go by various names. Güldemann nia AD. We cannot exclude the possibility that & Stoneking (2008) call them Tuu, Ju and Khoe, some of these languages differed so much from the usage followed here. Other authors, such as those surviving today as to have warranted the Blench (2006), term them Southern, Northern recognition of yet more language families than and Central Khoisan (or Khoesan), while Crawhall the Tuu, Ju and Khoe groupings already identi- (2006a) employs !Ui-Taa, Ju and Khoe, all derived fied