In the Light of Evolution Volume IV: The Human Condition (2010) / Chapter Skim
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5 Working Toward a Synthesis of Archaeological, Linguistic, and Genetic Data for Inferring African Population History--Laura B. Scheinfeldt, Sameer Soi, and Sarah A. Tishkoff
5 Working Toward a Synthesis of Archaeological, Linguistic, and Genetic Data for Inferring African Population History--Laura B. Scheinfeldt, Sameer Soi, and Sarah A. Tishkoff
Pages 81-100
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recent advances in genomic technology, however, have led to genome-wide studies of African sam ples. in this chapter, we discuss genetic variation in African populations contextualized with what is known about archaeological and linguistic variation.
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As displayed in Fig. 5.1, nigerKordofanian languages are spoken throughout western Africa, eastern Africa, central Africa, and southern Africa and include the common Bantu languages.
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The mtDnA, nry, and autosomal DnA studies demonstrate that the highest levels of genetic variation are present in African samples relative to non-Africans, consistent with a model of African ancestry for all modern humans [e.g., Cann et al.
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, is a period in the archaeological record that indicates a significant change in culture and subsistence technology in Africa. several sites in eastern, central, and southern Africa contain artifacts consistent with a shift in technology and population expansion ~75–55 kya, including hunting weapons, indications of increased plant utilization, signs of increased marine exploitation, and evidence of large-scale movement of red ochre (used for art)
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. Moreover, before the emergence of the natufianstyled artifacts, the archaeological record includes two artifact styles, the "Geometric Kebaran" and the "Mushabian" associated with Middle eastern and northern African populations, respectively (Bar-yosef, 1987)
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The genetic data appear to be consistent with the archaeological and linguistic data indicative of extensive population interactions between north African and Middle eastern populations. A recent nry study explores the distribution of haplogroups in a sample of African, Middle eastern, and european males (semino et al., 2004)
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inferred the history of pastoralism in Africa from a linguistic analysis of shared cognates. his findings support a relatively ancient emergence of pastoralism in northeastern Africa corresponding to eastern sudanic, Central sudanic, and possibly southern Cushitic speakers, followed by the subsequent spread of cattle keeping to western and southern Africa (ehret, 1967)
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. lactase persistence is present at high frequency in northern european dairying and African pastoralist populations; at moderate frequency in southern european and Middle eastern populations; and at low frequency in nonpastoral Asian, Pacific, American, and African populations (ingram et al., 2009)
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From page 89... ...
and is thought to have arisen ~6.8–2.7 kya in either the agropastoralist Afroasiatic populations that migrated into Kenya and Tanzania from ethiopia within the past 5,000 years or the nilo-saharan pastoralist populations that migrated into the region from southern sudan within the past 3,000 years, and the variant then subsequently spread throughout pastoral populations in eastern Africa relatively rapidly, con
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The savanna Bantu clade includes most of the contemporary languages spoken in eastern Africa, southeastern Africa, southwestern Africa, and the southern savanna belt. This reconstruction supports a model in which proto-Bantu emerged in western central Africa ~5,000 years ago and diversified and spread across the rainforest for ~2,000 years before the first archaeological evidence of eastern Bantu speakers in the Great lakes region (ehret, 2001)
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A recent analysis of genome-wide autosomal data is consistent with a large genetic impact of the Bantu expansion on most of sub-saharan Africa, as evidenced by the presence of niger-Kordofanian ancestry in many central, eastern, and southern African populations (Tishkoff et al., 2009)
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Therefore, the degree of correlation between genetic and linguistic variation varies depending on the populations being studied. studies of genetic variation within Africa, as mentioned above, have found extensive amounts of genetic variation relative to non-Africans owing to the fact that the "out of Africa" bottleneck significantly reduced genetic variation in non-Africans; however, most genetic studies of African populations are limited by the number of population samples included.
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(2009) emerging Clusters K 2 African, non-African 3 east Asian, oceanic, native American 4 eastern African 5 hadza, sandawe, sAK, Pygmy 6 Western Pygmy 7 Chadic, nilo-saharan 8 indian, oceanic 9 oceanic 10 native American 11 Mbuti Pygmy, sAK 12 Chadic/nilo-saharan speakers from northern Cameroon, Chad, and southern sudan 13 sandawe 14 Fulani neighbor-joining tree on the basis of pairwise population genetic distances that showed that the African samples clustered primarily by geographic region and to a lesser extent by linguistic affiliation with a few notable exceptions.
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have established a significant correlation between linguistic affiliation and genetic variation within three of the African language families, we wanted to explore to what degree samples plotted by genetic distance cluster by language family. We used multidimensional scaling (MDs)
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origin for the Fulani (ehret, 2008) , and there has been some speculation based on linguistic data that the Fulani migrated to central Africa from northern Africa or the Middle east (ehret, 2008)
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. We included central African populations with a sample of n ≥ 10, constructed a pairwise distance matrix using (δμ)
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. We included eastern African populations with a sample of n ≥ 10, constructed a pairwise distance matrix using (δμ)
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Geographically, however, the sandawe and hadza are extremely close to each other (150 km apart in Tanzania) , and both are geographically distant from the sAK populations residing in southern Africa.
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. Consistent with the mtDnA and nry data, our MDs analysis shows that the hadza and sandawe cluster closely together with each other and with other eastern African populations (Fig.
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as populations that speak linguistically similar languages are more likely to exchange genes. The pattern of genetic variation in Africa is also consis tent with geographic barriers limiting gene flow as exampled by the geographic/genetic distinction between northern African and sub-saharan African populations.
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