Monday, November 29, 2010

The Hadza are related to the South African Khoisan

In The Myth of East African Bushman, Morris presents evidence that the Bushmen were not present in East Africa. He based this on osteological and linguistic data and the relationship between the Hadza and Sandawe.

Morris makes it clear that the material he published denying the presence of Khoisan in East Africa is “arguable at best and must be rejected at worst” (Morris,p.87). This means that there is evidence supporting the presence and/or absence of the Khoisan in East Africa. As a result, his paper needs confirmation of his hypothesis since there is an alternative view.

The genetic, linguistic and osteological data does not support his hypothesis. It suggest that the Hadza are Khoisan and that they probably originally lived in East Africa and later migrated to South Africa.

We can reject Morris’ discussion of the osteological evidence in relation to the Hadza, because the only Hadza osteological crania for comparisons was destroyed during the WWII bombing of Berlin. As a result, you can not use this paper to claim that the Hadza are not Khoisan based on osteological evidence.

In the studies cited by Morris the researchers compared contemporary Sandawe and Khoisan crania with ancient East African skeletal remains. This does not prove anything because microevolutionary processes such as genetic drift and natural selection have probably affected skull morphology and may account for variations in ancient and contemporary crania.

I. Ribat claims that there are two extremes in African craniometrics: the khoisan and the west Africans. Craniofacial features, in relation to the skull can be shaped, in evolutionary terms by lower heritability and high biomechanical load. This is reflected in the morphological heterogeneity within the same population. Carlson and Gerven observed this phenomenon in their study of Nubian craniometrics.

Carlson and Gerven explained that the differences in Nubian skeletal remains was not the result of populaton changes resulting from invasion. They argued that the skeletal remains represented the same population.

They argued that instead of the changes in crania reflecting biological diffusion, the changes in facial features resulted from changes in diet that resulted in less masticatory stress associated with changes in subsistence patterns from the Mesolithic to Neolithic.

Given this reality, a relationship probably did exist between the ancient East Africans and Khoisan as indicated by typological features, while detail study of the crania might show difference between contemporary and ancient East African Khoisan as a result of changes in diet that led to variation in the size and position of the muscles of mastication which inturn led to reduction in the robustness of the craniofacial complex. This would explain why the use of multivariate techniques show variability between modern and ancient crania and skulls.

In relation to linguistic evidence, Morris noted that “the linguistic [relationship] is compelling” (p.87) and they are not rejected (p.89). As a result we cannot deny that a linguistic relationship exist between the speakers of Khoisan languages.

Morris claims that little if any genetic connect the Hadza and the other Khoisan people in South Africa. Morris ask us to ignore the presence of biological connections between the Hadza and SAK, because Ethiopians share with the SAK mtDNA and y-chromosome. As a result some differences between the SAK ,and the Hadza and Sandaw may be explained by interactions with neighboring East African populations.

But we can not ignore the phylogenetic evidence. And if molecular evidence exist for a relationship we must recognize it for what it is: a family relationship.

The South African Khoisan (SAK) have a distinct morphology that link them to the Hadza. In Tishkoff et al results have considerable relevancy in understanding the morophology of the Hadza. Morris mentions the research of Knight et al (2003) which was based on a small sample. The Tishkoff et al sample is much larger and can tell us considerably more about the Hadza.

In your post you discuss the Sandawe. We can not discuss the Hadza based on Sandawe , we must look at them based on their own characteristics. The Hadza surrounded by non-Khoisan speakers has remarkably sustained their genetic and cultural distinctiveness.

Tishkoff et al in The genetic structure and History of Aficans and African Americans (2009) noted that Hadza cluster near the SAK whose mtDNA, y-chromosome and autosomal chromosome indicates the most diverged genetic lineages in phylogenetic trees constructed from RST genetjc distance. These researchers found that the STRUCTURE and PCA indicate that the Hadza cluster near the SAK. They also pointed out that the Hadza and Sandawe show evidence of common ancestry but there is no evidence of recent gene flow; and that Khosian related art work is found in the area where these people reside.

Tishkoff et al in Y-chromosome evidence of a pastoral Migration through Tanzania
to South Africa(2008) noted that the Hadza have a high frequentcy of L3 and L2 (haplogroup common to west Africans). It was also made clear that the Hadza , Sandawe and SAK share the Eb1f-M293 haplotype.

Overall, Tishkoff et al in the Genetic History of African Click Speaking Populations (2007) found that the mtDNA of the Hadza cluster closely with the SAK, not other Tanzanians. This along with the high frequency of y-chromosome B2b which is shared with the SAK indicates a common ancestor.

There is some evidence of interactions between other Tanzanians and the Hadza. Tishkoff et al, suggest that the L4 lineages originated among the Hadza, and was introduced to neighboring groups via Hadza females.

Among the Khoisan there is a high frequentcy of LOd, but none has been found among the Hadza. Tishkoff et al (2007) believes that the loss of LOd may be the result of genetic drift.

In conclusion the biological and linguistic evidence suggest that the Hadza are a Khoisan population. The Morris (2003) paper does nothing to disconfirm my findings.
This fact is supported by the research of Tishkoff et al that indicate that the SAK originally lived in East Africa and that they later migrated into South Arfrica.

It was also revealed that the muscles of mastication probably led to reduction in the robustness of the craniofacial complex as Khoisan populations changed their diet. This would explain why the use of multivariate techniques show variability between modern and ancient Khoisan crania and skulls, while the typological features are consistent with a Khoisan origin.

The research shows that the effect of history have influenced the relationship between the Hadza and SAK, but the genetic evidence indicates a close relationship between the Hadza and SAK as indicated by y-chromosome Eb1f-M293, and B2b.

The absence of hg N among the Sandawe and SAK is probably the result of genetic drift. The fact that the Hadza mtDNA does not cluster with other Tanzanians is an indication that haplogroup N may be native to the Hadza.

It is interesting to note that mtDNA LO is primarily found among Khoisan and West Africans. Shows that at some point in prehistory the Khoisan had migrated into West Africa. As I point out in my paper that it was Khoisan from West Africa who migrated into North Africa and thence Iberia.

Given these reasons, I believe that the Khoisan took hg N to Eurasia. I do not believe the Khosian replaced any homo sapien sapien population. The Khoisan was the first anatomically modern human population to settle western Eurasia .


History of Click-Speaking Populations of Africa Inferred from mtDNA and Y Chromosome Genetic Variation
Mol. Biol. Evol. 2007 24: 2180-2195.

Genetic Structure in African Populations: Implications for Human Demographic History Cold Spring Harb Symp Quant Biol (2010) 0(2010): sqb.2009.74.053v1-sqb.2009.74.053

The Genetic Structure and History of Africans and African Americans Science (2009) 324(5930): 1035-1044

Y-chromosomal evidence of a pastoralist migration through Tanzania to southern Africa Proc. Natl. Acad. Sci. USA (2008) 105(31): 10693-10698

Carlson,D. and Van Gerven,D.P(1979). Diffussion, biological determinism and bioculdtural adaptation in the Nubian corridor,American Anthropologist, 81, 561-580.)

Morris, AG.(2003).The Myth of the East African 'Bushmen' The South African Archaeological Bulletin Vol. 58 ( 178): 85-90

1 comment:

HENCO said...

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