Are there "sub-races" within Africa?

[djoser-xyyman]

This is really a fascinating paper.

Apparently the pygmies are distant relatives to the San. The pygmies lost their original language but may have used "click" at one time.


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The Evolution of Human Genetic and Phenotypic Variation in
Africa


Michael C. Campbell1 and Sarah A. Tishkoff1,2
Michael C. Campbell: [e-mail]; Sarah A. Tishkoff: [e-mail]
1Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia,
Pennsylvania 19104
2Department of Biology, University of Pennsylvania, School of Arts and Sciences, Philadelphia,
Pennsylvania 19104


Abstract
Africa is the birthplace of modern humans, and is the source of the geographic expansion of ancestral
populations into other regions of the world. Indigenous Africans are characterized by high levels of
genetic diversity within and between populations. The pattern of genetic variation in these
populations has been shaped by demographic events occurring over the last 200,000 years. The
dramatic variation in climate, diet, and exposure to infectious disease across the continent has also
resulted in novel genetic and phenotypic adaptations in extant Africans. This review summarizes
some recent advances in our understanding of the demographic history and selective pressures that
have influenced levels and patterns of diversity in African population

[djoser-xyyman]

Non-African populations also appear to have fewer private alleles
and a subset of the genetic diversity present in sub-Saharan Africa, as expected under the
‘Recent African Origin’ model [1] (Figure 2).


Thus, arguably, a considerable amount of genetic and phenotypic diversity may
have been present at an early stage of modern human evolution.


Studies of global population structure in samples from the Human Genome Diversity Panel
(HGDP-CEPH) also identified substructure in Africa, particularly between hunter-gatherers
and other Africans [29,46].

A recent genome-wide study of a
much larger set of diverse Africans detected more extensive population structure within Africa
than had been previously observed. Specifically, an analysis of 848 short tandem repeat
polymorphisms (STRPs), 476 INDELs and 3 SNPs genotyped in ~2,400 individuals from 121
geographically diverse populations revealed the presence of 14 genetically distinct ancestral
population clusters in Africa [18]


Additionally, the above genome-wide analysis [18]in
geographically diverse Africans showed that Central African Pygmies share common ancestry
with several southern and eastern African Khoesan-speaking populations, who speak a
language with click consonants, suggesting that these contemporary hunter-gatherers may have
descended from a proto-Khoesan-Pygmy population of hunter-gatherers that diverged more
than 35 kya [18].


Specifically, data have shown that the inferred ancestors of
modern Pygmy hunter-gatherers and Bantu-speaking agriculturalists could have diverged as
long as 70 kya [49], and that ancestral western and eastern Pygmy populations separated more
than 18 kya [48] with subsequent genetic differentiation among the western Pygmies within
the past 2,800 years [50]. The subtle structure among western Pygmies may be due to recent
geographic isolation, genetic drift, and differential levels of admixture between Pygmies and
neighboring Bantu-speaking populations [18,49,50,52–54]. Overall, these patterns of genetic
and phenotypic variation suggest that African populations have maintained a large and
subdivided population structure throughout much of their evolutionary history