Category Archives: African genetics

SW African Bantu matrilineages

Prolific researcher Chiara Barbieri has put online another interesting study on African genetics, this time about the Bantu populations of Southwestern and Central-Southern Africa (i.e. Namibia, Angola, Botswana and Zambia).
Chiara Barbieri et al., Migration and interaction in a contact zone: mtDNA variation among Bantu-speakers in southern Africa. bioRXiv 2014. Freely accessible (pre-pub) → LINK


Bantu speech communities expanded over large parts of sub-Saharan Africa within the last 4000-5000 years, reaching different parts of southern Africa 1200-2000 years ago. The Bantu languages subdivide in several major branches, with languages belonging to the Eastern and Western Bantu branches spreading over large parts of Central, Eastern, and Southern Africa. There is still debate whether this linguistic divide is correlated with a genetic distinction between Eastern and Western Bantu speakers. During their expansion, Bantu speakers would have come into contact with diverse local populations, such as the Khoisan hunter-gatherers and pastoralists of southern Africa, with whom they may have intermarried. In this study, we analyze complete mtDNA genome sequences from over 900 Bantu-speaking individuals from Angola, Zambia, Namibia and Botswana to investigate the demographic processes at play during the last stages of the Bantu expansion. Our results show that most of these Bantu-speaking populations are genetically very homogenous, with no genetic division between speakers of Eastern and Western Bantu languages. Most of the mtDNA diversity in our dataset is due to different degrees of admixture with autochthonous populations. Only the pastoralist Himba and Herero stand out due to high frequencies of particular L3f and L3d lineages; the latter are also found in the neighboring Damara, who speak a Khoisan language and were foragers and small-stock herders. In contrast, the close cultural and linguistic relatives of the Herero and Himba, the Kuvale, are genetically similar to other Bantu-speakers. Nevertheless, as demonstrated by resampling tests, the genetic divergence of Herero, Himba, and Kuvale is compatible with a common shared ancestry with high levels of drift and differential female admixture with local pre-Bantu populations.

Figure 1: Map showing the rough geographical location of populations, 
colored by linguistic affiliation. Abbreviations of population labels are 
as specified in Table 1.

In spite of the Bantu-centric approach of the study, which also has its merits, my greatest interest is rather in the less typically Bantu lineages, which speak of admixture with several pre-Bantu populations.
In this sense I find the following highlights:

Fig. S2 (annotated in green by Maju): CA plots based on haplogroup frequencies. Left: all the dataset, right: excluding outliers.

L3d and L3f founder effect:
The Himba and Herero, as well as the non-Bantu pastoralists Damara make one distinctive cluster defined by the high frequencies of haplogroup L3d, as well as L3f (not present among the Damara but found among the Kuvale). As discussed in the paper, the Himba and Herero may be related to the Kuvale of SW Angola but they have notable differential levels (or directionality) of aboriginal admixture. 
As both L3d and L3f are present in West and East Africa alike, it is interesting to track the specific subhaplogroups implicated in this founder effect, something done in fig. 4. 
The main L3d sublineage is L3d3a1, whose haplotype network shows a largely Khoisan centrality (not Damara) although this node is shared also by some unspecified “other Bantu”. The Southern Africa specificity of L3d3a was already noticed in the past (see here). So it is very possible that we are before an aboriginal Southern African lineage, maybe arrived with the first Khoisan Neolithic (or whatever other ancient flow) rather than a Bantu-specific founder effect. 
The main L3f subhaplogroup is L3f1b4a, which seems more specifically Bantu, with a major branch concentrated among the Himba, Herero and Kuvale. This lineage is not found among the Damara in spite of the other strong affinity of this Khoisan population towards the Himba and Herero. L3f1b is found in Southern Africa, Kenya and Oman (per Bihar 2008), so we are probably before a distinctive East African element, not too likely to be genuinely Bantu but possibly just assimilated into Bantu ethnic identity. 
Even if both lineages converge in the Himba and Herero, they are almost certainly different inputs, one of Damara (herder Khoisan) origin and the other of Bantuized East African origin maybe.
L1b founder effect:
L1b is essentially a West African lineage concentrated in the Sahel area from Chad westwards (although L1b1a2 is from the Nile basin). A particularly high frequency population are the Fulani pastoralists, original from the Westernmost African plateaus, who ruled many kingdoms in West Africa between the collapse of the colonial rule by Morocco and the consolidation of the European conquest of the continent.
As this study does not dwell in sublineages, we cannot understand the most likely specific origins of it among several Southern African populations, specifically the pooled NE Zambians (13%) and the Fwe and Shanjo of SW Zambia (24-27%).
In any case it is a notorious founder effect, almost absent in other Bantus of the area (0-10%).
Typical L0d Khoisan admixture:
This element is concentrated in Botswana (~25%) and with highest frequencies in the SW Kgalagadi (53%). It is also important among the Kuvale of SW Angola (21%). Other Bantu populations in this dataset have frequencies under 10%, some even zero. The Damara have 13%.
We know from previous studies that it is also found at high frequencies among the Xosha of South Africa (L0d3).
While L3h appears marked in the graph, the lineage is in fact absent in all populations except at very low frequency among the Kuvale (2%), so it does not seem actually of any relevance. 
Less typical L0k around SW Zambia:
While L0k is generally considered an aboriginal Southern African lineage it has a much more northernly distribution than the more common and surely older L0d. Its area of greatest commonality seems to be SW Zambia (see here and here).
This study confirms this distribution:

Supplementary Figure S3[A]: Haplogroup frequencies of important haplogroups in the populations studied here. A: Haplogroups L0d and L0k.(…)

The size of the circles is proportional to the sample size.

High frequencies of L1c (Pygmy admixture marker) among Southern African Bantus:
An interesting element is the commonality of L1c, typical of Western Pygmies and some other populations from Gabon (possibly representative of the wider West-Central Africa jungle region, not too well studied otherwise), among almost all Bantu populations in this dataset. 
The exceptions are the Herero, Himba, Kgalagadi and Tswana (0%), as well as the NE Zambians (4%). All the rest have frequencies between 12% and 30%. Even the non-Bantu Damaras have 11% of it.
In my understanding this almost certainly implies a notable level of admixture with Western Pygmies of the Bantus from especially Angola and West Zambia. A phenomenon that may be widespread in Central-West Africa. 
It is notable however that at least many of the populations with the highest likely Khoisan admixture (in its various forms, discussed in the previous sections) have the lesser frequencies of L1c (Pygmy admixture). So to a great extent these two aboriginal influences in Bantu mtDNA seem mutually exclusive and were probably produced after settlement rather than “on the march”. 
This in turn arises some interesting questions about the ethnic geography of Africa before the Bantu expansion. 

Update: I just noticed that Ethiohelix has parsed the haplogroups’ frequency into a very helpful chartLINK.

See also:

East African mtDNA charts at Ehio Helix

There’s a (thankfully) growing interest in African genetics, both because of its importance for the origin of Humankind as a whole and also for its more direct relevance for Africans and people of recent African descent elsewhere. Therefore I can’t but emphasize again the great work that Ethio Helix blog is doing in this aspect.
Today Ethio Helix gifts us with a most informative visual synthesis of East African mtDNA in form of bar charts. These are extremely interesting because of the wild array of lineages that this African region has, including quite significant amounts of less frequent lineages like L4, L5 or L6, or also the more extended but still worth studying L0 (and of course L2 and L3, as well as the occasional L1).
So I strongly recommend you to take a look. If you have any problems with the graphs (Google seems a bit buggy on them, he says), I solved them by mere zooming out (some sort of white layer was obscuring the rightmost part of them).

Update: it does not work well with Chrome (slow on Windows, does not work at all on Ubuntu) but it works perfect with Firefox.

A complementary Y-DNA chart is linked at this older post.

Posted by on December 9, 2013 in African genetics, mtDNA, population genetics


Reconstructing human demographic history from IBS segments

Figure 1. An eight base-pair tract of identity by state (IBS).
Identity-by-state (IBS) segments are those located between any two SNPs (polymorphisms, letters that vary among individuals). According to this new paper, they seem to be evolutionarily neutral and therefore their length, modified by recombination events each new generation, is a good trail to reconstruct human demographic history.
Kelley Harris & Rasmus Nielsen, Inferring Demographic History from a Spectrum of Shared Haplotype Lengths. PLoS Genetics 2013. Open accessLINK [doi:10.1371/journal.pgen.1003521]


There has been much recent excitement about the use of genetics to elucidate ancestral history and demography. Whole genome data from humans and other species are revealing complex stories of divergence and admixture that were left undiscovered by previous smaller data sets. A central challenge is to estimate the timing of past admixture and divergence events, for example the time at which Neanderthals exchanged genetic material with humans and the time at which modern humans left Africa. Here, we present a method for using sequence data to jointly estimate the timing and magnitude of past admixture events, along with population divergence times and changes in effective population size. We infer demography from a collection of pairwise sequence alignments by summarizing their length distribution of tracts of identity by state (IBS) and maximizing an analytic composite likelihood derived from a Markovian coalescent approximation. Recent gene flow between populations leaves behind long tracts of identity by descent (IBD), and these tracts give our method power by influencing the distribution of shared IBS tracts. In simulated data, we accurately infer the timing and strength of admixture events, population size changes, and divergence times over a variety of ancient and recent time scales. Using the same technique, we analyze deeply sequenced trio parents from the 1000 Genomes project. The data show evidence of extensive gene flow between Africa and Europe after the time of divergence as well as substructure and gene flow among ancestral hominids. In particular, we infer that recent African-European gene flow and ancient ghost admixture into Europe are both necessary to explain the spectrum of IBS sharing in the trios, rejecting simpler models that contain less population structure.

The most interesting graph, synthesizing the result for standard HapMap European and African proxy samples is figure 7. However I have major issues with the age estimates, which seem to be half what is needed to be realistic according to archaeological and other genetic data (unlineal haplogroup history, for example). Therefore I have annotated it with a revised timeline, so it fits better with the objective data:

Figure 7. A history inferred from IBS sharing in Europeans and Yorubans.
This is the simplest history we found to satisfactorily explain IBS tract sharing in the 1000 Genomes trio data. It includes ancient ancestral population size changes, an out-of-African bottleneck in Europeans, ghost admixture into Europe from an ancestral hominid, and a long period of gene flow between the diverging populations.
(Right margin annotations by Maju).

Indeed the simplest revision of the time-scale was to double it. I guess it can be refined a bit more than that, maybe pushing it a bit further into the past, but the alternative time-scale I propose fits closely enough with known archaeological data like the time of the OoA to Arabia and Palestine or the spread of Acheulean (and therefore H. ergaster, common ancestor of Neanderthals and H. sapiens) out of Africa c. 1 Ma ago to illustrate that the reconstruction seems pretty much correct overall but fails when estimating the dates (because of scholastic-autistic academic biases that are too common in the field of human population genetics).

Update: even Dienekes agrees, on his own well documented reasoning, with a x2 mutation rate being necessary for the above graph.


New sublineages in Y-DNA haplogroups A3 and B2a

Improving the knowledge of African genetics.
Rosaria Scozzari et al., Molecular Dissection of the Basal Clades in the Human Y Chromosome Phylogenetic Tree. PLoS ONE 2013. Open accessLINK [doi:10.1371/journal.pone.0049170]

One hundred and forty-six previously detected mutations were more precisely positioned in the human Y chromosome phylogeny by the analysis of 51 representative Y chromosome haplogroups and the use of 59 mutations from literature. Twenty-two new mutations were also described and incorporated in the revised phylogeny. This analysis made it possible to identify new haplogroups and to resolve a deep trifurcation within haplogroup B2. Our data provide a highly resolved branching in the African-specific portion of the Y tree and support the hypothesis of an origin in the north-western quadrant of the African continent for the human MSY diversity.

Figure 1. Revised topology of the deepest portion of the human MSY tree.
The names of the mutations genotyped are indicated on the branches (green, mutations from the paper by Karafet et al. [14]; black, mutations from the paper by Cruciani et al. [16];
red, previously undescribed mutations, see text). For the sake of
clarity, the internal structure of haplogroups B-M108.1 (2 branches) and
B-50f2(P) (8 branches) is not shown (black triangles). The phylogenetic
position of mutations mapping within haplogroup CT is shown in Figure S1.
Dashed lines indicate putative branchings (no positive control
available). The microsatellite intermediate allele DYS449.2, that was
found to delineate new phylogenetic structure in human Y chromosome
haplogroup tree [42], was not observed in 19 Y*(xBT) and 4 B chromosomes analyzed.

Notice that the nomenclature per ISOGG is right now as follows:

  • A1b-V148 is now known as A0
  • A1a-V4 retains the name A1a
  • A2-V50 is A1b1a
  • A3-M32 is A1b1b
    • A3a-M28 is A1b1b1
    • A3b-M144 is A1b1b2

See ISOGG for more details.

Leave a comment

Posted by on May 17, 2013 in Africa, African genetics, Y-DNA


Synthesis of the Spanish-language series on the expansion of H. sapiens (2)

One of the reasons I have been a bit too saturated and maybe not writing as much as usual is that I am collaborating in a series in Spanish language for the blog Noticias de Prehistoria – Prehistoria al Día.
I already mentioned last month the initial article[es] of the series by David Sánchez, which dealt with the African Middle Paleolithic (MSA, Lupembian, Aterian, etc.) We have not been idle in the meantime but actually wrote a number of other articles that may well be of your interest:
There is still a lot to do for the series to be complete but the time for a synthetic review in this blog is quite overdue. I will skip the brief intro to population genetics on the belief that most readers here have a decent idea, but the other three articles ask for due mention.

Expansion of H. sapiens in Africa (genetic viewpoint)

This is something that complements David’s analysis of the African MP and that to a great extent I dealt with already at my former blog Leherensuge. I like graphs and maps because they often tell more than just words:

Basic mtDNA tree of Humankind
Branch length is proportional to coding region mutations from root per PhyloTree v.15 (L0k excepted)

We can see in this graph two main “moments” of diversification or expansion:
  1. The L0 and L2-6 nodes, followed soon by the L1 and L0a’b’f’k nodes
  2. The L0a’b’f, L0d and L2’3’4’6 nodes
The latter may well be calibrated with the archaeological evidence for the arrival of H. sapiens (MSA) to Southern Africa (L0d), which may be as old as 165 Ka but shows a clear increase in density since c. 130 Ka. I’d rather lean for the later date, that is roughly coincidental with the beginning of the Abbassia Pluvial, which must have provided good opportunities for expansion also in more northernly latitudes (the other nodes).
The first expansion is harder to estimate but c. 160 Ka. is a time in which we can see some of the first signs of expansion of our species within Africa (Jebel Irhoud and the already mentioned first Southern African MSA) so it is a tentative date. 
The geography of both expansions should be as follows (based on the raw data of Behar 2008):

Approx. geography of the first expansion of H. sapiens
(Purple dotted area indicates the max. likelihood for ‘mtDNA Eve’ location)
Approx. geography of the second expansion of H. sapiens

I also mentioned the expansion of L3, which preludes the migration Out of Africa, but this was already discussed in this entry.

Arrival to Arabia and Palestine

While most of the entries I am doing for this series deal with the genetic aspects, in this case I worked mostly with the archaeology, recycling many materials that are readily available in this blog and achieving the following synthetic map (recycling one by Armitage 2011) as central element of the article:

In addition to reviewing the archaeological discoveries of the last few years (and few older ones) I also discussed the issue of Neanderthal admixture, which most likely happened in this phase, and the possibility of some L(xM,N) lineages found in Arabia being from this period (see here).

Synthesis of Asian Prehistory

The last article so far in the series, authored by David Sánchez, has been published just today and is a very good visual review of the complex archaeological record of most of Asia in the period that interests us (most Middle Paleolithic with marginal mention of the earliest UP of West Asia, Siberia and neighboring areas, which will be reviewed more in depth in later articles). Probably the maps say it all, although we must understand that they only consider the best known sites:

Prior to Toba event (120-74 Ka BP)
(open circles: human remains, dots: other archaeological sites)
(notice that the date of Narmada hominin is most unclear, what is not reflected in the map)
Blue: 74-45 Ka BP
(stars: Neanderthal sites, open circles: other human remains, dots: archaeological sites, black: previous map)
Red: 45-35 Ka BP
(stars: neanderthal sites, open circles: other human remains, dots: archaeological sites, black & blue: previous maps)
Green: later expansion of H. sapiens in Northern Asia
(stars: Neanderthals, open circles: other human remains, dots: other archaeological sites, black, blue & red: previous maps)

I must say that the design of the maps is not quite the way I would have done myself but is still interesting. Very especially I miss lots of info on post-Toba South Asia. Also the Altai transition is not really well explained in my understanding. On the other hand East Asia is full of details and the overall picture of the archaeology of the Eurasian expansion is well described nonetheless.

PS- from the commentaries by David at his blog, it seems clear that he gives for granted the occupation of South Asia after Toba and therefore he did not consider it important to mark any more recent sites in the subcontinent. 


    Eye and skin pigmentation genetics: Cape Verdeans as informative population

    Cape Verde from space
    Still getting updated with the backlog. Here there is an interesting study on human pigmentation using the heavily admixed Cape Verdean (essentially West African + West Iberian) population as reference.
    Sandra Beleza et al., Genetic Architecture of Skin and Eye Color in an African-European Admixed Population. PLoS Genetics 2013. Open accessLINK [doi:10.1371/journal.pgen.1003372]


    Variation in human skin and eye color is substantial and especially apparent in admixed populations, yet the underlying genetic architecture is poorly understood because most genome-wide studies are based on individuals of European ancestry. We study pigmentary variation in 699 individuals from Cape Verde, where extensive West African/European admixture has given rise to a broad range in trait values and genomic ancestry proportions. We develop and apply a new approach for measuring eye color, and identify two major loci (HERC2[OCA2] P = 2.3×10−62, SLC24A5 P = 9.6×10−9) that account for both blue versus brown eye color and varying intensities of brown eye color. We identify four major loci (SLC24A5 P = 5.4×10−27, TYR P = 1.1×10−9, APBA2[OCA2] P = 1.5×10−8, SLC45A2 P = 6×10−9) for skin color that together account for 35% of the total variance, but the genetic component with the largest effect (~44%) is average genomic ancestry. Our results suggest that adjacent cis-acting regulatory loci for OCA2 explain the relationship between skin and eye color, and point to an underlying genetic architecture in which several genes of moderate effect act together with many genes of small effect to explain ~70% of the estimated heritability.

    Children of Praia
    (CC by Otimarte)
    Most interestingly maybe the authors conclude that KITLG, a gene which displays large differences in allele frequency between Africa and Eurasia and has been therefore suggested to be a cause of pigmentation differences, does not actually play any obvious role in this matter.
    HERC2 (OCA2) is confirmed to be very important in eye color (semi-recessive inheritance for blue color), the only other gene known to affect eye color is SLC24A5, which is mostly involved in skin pigmentation however.  
    SLC24A5 and SLC45A2 are confirmed as important pigmentation genes. However two otherwise unsuspecting genes, APBA2 (near OCA2) and GRM5TYR, are found to have also important impact in skin pigmentation.
    Still most (~3/5) of the inherited pigmentation traits remain unexplained and are probably caused by some sort of complex interactions. Eye and skin pigmentation have no strong genetic correlation apparently.
    Some interesting images from the paper:

    Figure 1. Relationship of geography and ancestry to skin and eye color.
    Individual ancestry proportions for Cape Verdeans displayed on all four panels were obtained from a supervised analysis in frappe
    with K = 2 and HapMap’s CEU and YRI fixed as European and African
    parental populations. (a) Bar plots of individual ancestry proportions
    for Cape Verdeans across the islands. The width of the plots is
    proportional to sample size (Santiago, n = 172; Fogo, n = 129; NW
    cluster, n = 192; Boa Vista, n = 27). The proportion of African vs.
    European ancestry of the individuals is indicated by the proportion of
    blue vs. red color in each plot. (b) Individual African ancestry
    distribution in the total cohort of 685 Cape Verdeans (histogram) and in
    802 African Americans (kernel density curve) from the Family Blood
    Pressure Program (FBPP) [21].
    (c) Scatter-plot of skin color vs. Individual African ancestry
    proportions. Skin color is measured by the MM index described in
    Material and Methods. (d) Scatter-plot of eye color vs. Individual
    African ancestry proportions. Eye color is measured by the T-index,
    described in Figure 2 and Material and Methods. Points in scatter-plots are color coded according to the island of origin of the individuals.
    Figure 3. GWAS results for skin and eye color in the total Cape Verdean cohort.
    Results are shown as −log10(P
    value) for the genotyped SNPs. Plots are ordered by chromosomal
    position. (a,c) Genotype and admixture association scan results for skin
    color. (b,d) Genotype and admixture association scan results for eye
    color. (a,b) show the P values obtained in the initial scans and (c,d) the P values of the following scans adjusting for the strongest associated SNP (in SLC24A5 for skin color and in HERC2 for eye color). Dashed red lines correspond to the genome-wide significance threshold (P<5×10−8 in the genotype scan; P<7×10−6
    in the ancestry scan [see Material and Methods]). The location and
    identity of candidate genes are colored to correspond with chromosomal
    location; individual SNPs are given in Table 1.
    Figure 7. Genetic architecture of skin color variation.
    Effect sizes of the loci associated with skin color. Effect values
    represent the beta values obtained from a regression model containing
    the four associated loci plus ancestry. (b) The pie chart represents the
    proportion of phenotypic variation accounted for by the different
    components, including non-heritable factors (~20%), the four major loci
    (~35%, color-coded as in [a]), and average genomic ancestry (44%). The
    heritable contributions were estimated by regression and variance
    decomposition as described in Material and Methods, and are also
    represented below the pie chart separately as grey (genomic ancestry) or
    open (four major loci) areas. However, because of admixture
    stratification, the heritable contributions overlap as described in the


    Khoesan and Coloured autosomal DNA in context

    There has been a number of studies coming out recently on Khoesan genetics but this one does not seem to be just redundant, providing some extra information instead.

    Desiree C. Petersen et al., Complex Patterns of Genomic Admixture within Southern Africa. PLoS Genetics 2013. Open accessLINK [doi:10.1371/journal.pgen.1003309]


    Within-population genetic diversity is greatest within Africa, while between-population genetic diversity is directly proportional to geographic distance. The most divergent contemporary human populations include the click-speaking forager peoples of southern Africa, broadly defined as Khoesan. Both intra- (Bantu expansion) and inter-continental migration (European-driven colonization) have resulted in complex patterns of admixture between ancient geographically isolated Khoesan and more recently diverged populations. Using gender-specific analysis and almost 1 million autosomal markers, we determine the significance of estimated ancestral contributions that have shaped five contemporary southern African populations in a cohort of 103 individuals. Limited by lack of available data for homogenous Khoesan representation, we identify the Ju/’hoan (n = 19) as a distinct early diverging human lineage with little to no significant non-Khoesan contribution. In contrast to the Ju/’hoan, we identify ancient signatures of Khoesan and Bantu unions resulting in significant Khoesan- and Bantu-derived contributions to the Southern Bantu amaXhosa (n = 15) and Khoesan !Xun (n = 14), respectively. Our data further suggests that contemporary !Xun represent distinct Khoesan prehistories. Khoesan assimilation with European settlement at the most southern tip of Africa resulted in significant ancestral Khoesan contributions to the Coloured (n = 25) and Baster (n = 30) populations. The latter populations were further impacted by 170 years of East Indian slave trade and intra-continental migrations resulting in a complex pattern of genetic variation (admixture). The populations of southern Africa provide a unique opportunity to investigate the genomic variability from some of the oldest human lineages to the implications of complex admixture patterns including ancient and recently diverged human lineages.

    The array of Khoesan populations senso stricto analyzed in this study is much smaller than that of Schebusch 2010 but this study has the advantage of including Cape Coloureds and their Baster relatives, partially descendants from the otherwise extinct pastoralist Khoekhoe (Hottentots, now considered a derogative term) who lived in much of Southern Africa upon the arrival of Bantu and Europeans, as well as the amaXhosa, a Bantu people which clearly display marked Khoesan admixture.

    Figure 1. Map of southern Africa
    showing distribution of sampling per population identifier and
    significant historical events that likely shaped ancestral

    There is brief mention of maternal and paternal DNA. Just to mention that mtDNA being mostly aboriginal (L0d/L0k) among the Khoesan (86-100%), the Coloureds (68%) and even the Xhosa (47%, all L0d), while aboriginal Y-DNA (essentially A2b and A2c2, plus occasional B2) is concentrated among the Ju/’hoan, with the !Xun being instead dominated by E1b1-M275, of putative East African (Nilotic?) origins. This is consistent with the !Xun being historically pastoralists. European patrilineages, notably R1b, are dominant among the Baster (92%) and Cape Coloured (71%).
    Coloureds only make up some 9% of South African population but they dominate the countryside in much of the former Cape Province. Namibian Basters are a subset of them who migrated northwards in 1868.

    Figure 2.  PCA and STRUCTURE analysis (click to expand)
    We can see in the graphics above how the North Cape Coloured and Baster only display minor Bantu admixture, being essentially a variable mix of European and Khoesan ancestry, with probably also some Malay input (apparent in the increase of the blue component relative to the European reference). Instead East Cape and Cape Town (D6) Coloured appear to have greater apportion of Bantu ancestry and, especially the later, a notable increase of the East Asian input.
    The STRUCTURE graph, particularly at K=9, is also informative about other African populations but I won’t dwell in that here. 
    The authors also made an interesting exercise of analysis using Ancestry Informative Markers with the !Xun and Xhosa:

    Figure 4. Ju/’hoan-Yoruba ancestry
    informative markers (AIMs) defined ancestral contributions to the !Xun
    and amaXhosa, providing evidence for two distinct !Xun lineages with
    differing ancestral contributions.
    It seems evident that much of the !Xun ancestry (up to 70%) does not fall in either (Ju/’hoan-Yoruba) category but it is something else, probably specific to this people. The Xhosa Khoesan ancestry also seems closer to the pastoralist !Xun than to the (likely more genuinely ancient) Ju/’hoan. 

    There is some more info in the paper but I feel that the essentials are sufficiently covered here. 

    See also: