Luxmanda: a 3,000 years-old proto-Horner in Tanzania

I knew, more intuitively than rationally, that the Horner (Ethiopian, Somali, Eritrean) type of Afro-Eurasian admixture was very old but no idea it was so much. I knew that West Eurasian Upper Paleolithic had an impact on Africa (LSA) but I did not know it went so deep South nor that it had left such a massive legacy as ancient DNA reveals.

Pontus Skoglund et al. Reconstructing Prehistoric African Population Structure. Cell 2017 (open access). DOI:10.1016/j.cell.2017.08.049

The data analysis speaks volumes by itself:

Figure 1 - Overview of Ancient Genomes and African Population Structure

Figure S2 - Ancient Individuals and African Population Structure

Figure 2 - Ancestral Components in Eastern and Southern Africa

We show bar plots with the proportions inferred for the best model for each target population. We used a model that inferred the ancestry of each target population as 1-source, 2-source, or 3-source mixture of a set of potential source populations.

So much that I don't really know what else to say. Of course this is just a sample of what there is in the paper, read it. I'm sure there will be plenty of comments even if the study was published months ago.

Regarding haploid DNA, I don't see anything outstanding but, as I know there is generally quite a bit of interest, these are screenshots of the ancient lineages found (full data in the supp. materials of the study):

Ancient Y-DNA (screenshot)

Ancient mtDNA (screenshot)

Related: No Iberian in Iberomaurusian.

Correction: I first titled this "a 30,000 years-old...". That was a major error on my part and I apologize for any confusion it may have caused. Thanks to Capra Internetensis for spotting it.

No Iberian in Iberomaurusian

After almost a century of controversy on the matter, it seems that archaeogenetics solved the riddle. Not in the sense I thought it would but it did anyhow.

Marieke van de Loosdrecht et al., Pleistocene North African genomes link Near Eastern and sub-Saharan African human populations. Science 2018 (pay per view). DOI:10.1126/science.aar8380 -- See also supplementary materials (free but hard to find). 

Ancient DNA samples from Taforalt (Iberomaurusian or Oranian culture, Upper Paleolithic of North Africa) show no trace of Paleoeuropean ancestry (WHG), however they show strong affinity to West Asians of Palestinian type, showing also some significant amount of African Aboriginal ancestry, probably closer to East African Hadza and Sandawe and ancient Mota than to West African types. The result is something roughly similar to Afars but not quite the same in any case. 

Fig. S8 - Taforalt individuals on the top PCs of present-day African, Near Eastern and South European populations.

Fig. S11 - ADMIXTURE results for a few informative K values.

So the conclusion must thus be that the Eurasian influence in North African Upper Paleolithic (call it Iberomaurusian, Oranian or my personal unorthodox preference: Taforaltian) arrived from West Asia with whichever intermediate stage in Egypt and Cyrenaica, where that influence is quite apparently much older in the archaeological record. This seems contradictory to the chronology of Taforaltian, with Western sites producing older radiocarbon dates but the genetic data seems overwhelming. 

I must say I wish they would have contrasted with older (and available) Paleoeuropean samples than WHG (Epipaleolithic) but I guess that some WHG influence would have shown up if there was some older European influx because the various Paleoeuropean layers are not disconnected. But it is still something someone should test, just in case. 

Haploid DNA

The Taforalt sample was rich in mtDNA U6a, with also one instance of M1b:

All six male samples carried Y-DNA E1b1b, with most of them being well defined as E1b1b1a1-M78 (see table S16 for details).


Related: Luxmanda: a 3,000 years-old proto-Horner in Tanzania.

Genetic structure in South-Eastern Africa

Quickies

Another quite interesting paper on Khoesan and Southern African genetics:

Caitlin Uren et al., Fine-Scale Human Population Structure in Southern Africa Reflects Ecogeographic Boundaries. Genetics 2016. Freely accessible → LINK [doi:10.1534/genetics.116.187369]

Abstract

Recent genetic studies have established that the KhoeSan populations of southern Africa are distinct from all other African populations and have remained largely isolated during human prehistory until ∼2000 years ago. Dozens of different KhoeSan groups exist, belonging to three different language families, but very little is known about their population history. We examine new genome-wide polymorphism data and whole mitochondrial genomes for >100 South Africans from the ≠Khomani San and Nama populations of the Northern Cape, analyzed in conjunction with 19 additional southern African populations. Our analyses reveal fine-scale population structure in and around the Kalahari Desert. Surprisingly, this structure does not always correspond to linguistic or subsistence categories as previously suggested, but rather reflects the role of geographic barriers and the ecology of the greater Kalahari Basin. Regardless of subsistence strategy, the indigenous Khoe-speaking Nama pastoralists and the N|u-speaking ≠Khomani (formerly hunter-gatherers) share ancestry with other Khoe-speaking forager populations that form a rim around the Kalahari Desert. We reconstruct earlier migration patterns and estimate that the southern Kalahari populations were among the last to experience gene flow from Bantu speakers, ∼14 generations ago. We conclude that local adoption of pastoralism, at least by the Nama, appears to have been primarily a cultural process with limited genetic impact from eastern Africa.

 

Figure 2

Five spatially distinct ancestries indicate deep population structure in southern Africa. Using global ancestry proportions inferred from ADMIXTURE k = 10, we plot the mean ancestry for each population in southern Africa. The five most common ancestries in southern Africa, from the Affymetrix HumanOrigins data set, are shown separately in A–E. The x- and y-axes for each map correspond to latitude and longitude, respectively. Black dots represent the sampling location of populations in southern Africa. The third dimension in each map (depth of color) represents the mean ancestry proportion for each group for a given k ancestry, calculated from ADMIXTURE using unrelated individuals, and indicated in the color keys as 0–100% for five specific k ancestries. Surface plots of the ancestry proportions were interpolated across the African continent.

See also:

• Relevant article at Science Daily
• Khoesan and Coloured autosomal DNA in context
• Khoesan genetics helping to understand the evolutionary history of Humankind as a whole
• SW African Bantu matrilineages
• Khoe-San matrilineages and prehistory
• Khoisan autosomal genetics

African admixture events

Quickies

This paper is probably of interest to many but I don't have the insight to make a proper analysis. Just to mention that I feel deeply uncomfortable with the use of the "Sub-Saharan" term, which has so many wrong ideas attached to it, particularly the word "sub" (under, below) that it really irks me. Why not Trans-Saharan or Ultra-Saharan?, very Roman and not the least Eurocentric but definitely not just all kinds of wrong, as "Sub" is. Why not Tropical and Southern Africa?

Sub-Saharan is not just implicitly Eurocentric and almost certainly racist (sub-what?! subordinated?, sub-human maybe?) but, most importantly, it is geometrically and geographically very wrong. The South is not "under" the North: they are all on the same spheroid surface or equivalent cuasi-plane. Even a primary school student knows that!

Anyhow, this is what they have to say in minimalistic terms:

George BJ Busby et al., Admixture into and within sub-Saharan Africa. eLife 2016. Open access → LINK [doi: eLife 2016;5:e15266]

Similarity between two individuals in the combination of genetic markers along their chromosomes indicates shared ancestry and can be used to identify historical connections between different population groups due to admixture. We use a genome-wide, haplotype-based, analysis to characterise the structure of genetic diversity and gene-flow in a collection of 48 sub-Saharan African groups. We show that coastal populations experienced an influx of Eurasian haplotypes over the last 7000 years, and that Eastern and Southern Niger-Congo speaking groups share ancestry with Central West Africans as a result of recent population expansions. In fact, most sub-Saharan populations share ancestry with groups from outside of their current geographic region as a result of gene-flow within the last 4000 years. Our in-depth analysis provides insight into haplotype sharing across different ethno-linguistic groups and the recent movement of alleles into new environments, both of which are relevant to studies of genetic epidemiology.

Figure 4. Inference of admixture in sub-Saharan African using GLOBETROTTER. (A) For each group we show the ancestry region identity of the best matching source for the first and, if applicable, second events. Events involving sources that most closely match FULAI and SEMI-BANTU are highlighted by golden and red colours, respectively. Second events can be either multiway, in which case there is a single date estimate, or two-date in which case 2ND EVENT refers to the earlier event. The point estimate of the admixture date is shown as a black point, with 95% CI shown with lines. MIXTURE MODEL: We infer the ancestry composition of each African group by fitting its copying vector as a mixture of all other population copying vectors. The coefficients of this regression sum to 1 and are coloured by ancestry region. 1ST EVENT SOURCES and 2ND EVENT SOURCES show the ancestry breakdown of the admixture sources inferred by GLOBETROTTER, coloured by ancestry region as in the key top right. (B) and (C) Comparisons of dates inferred by MALDER and GLOBETROTTER. Because the two methods sometimes inferred different numbers of events, in (B) we show the comparison based on the inferred number of events in the MALDER analysis, and in (C) for the number of events inferred by GLOBETROTTER. Point symbols refer to populations and are as in Figure 1 and source data can be found in Figure 4—source data 1

MtDNA U6 in Aurignacian Europe

The U6 haplogroup of Pestera Muierii is officially confirmed. 

Extra-officially, it also seems confirmed mtDNA H in Magdalenian El Mirón, another of the haplogroup challenged (without any reasoning) by Fu et al. In this last case, my sources suggest that Fu surely tested a bone belonging to a different individual, because the heap of bones could well include several people and the bones tested by Hervella (a tooth) and Fu (a femur) were different.

Anyhow, to the matter at hand:

Montserrat Hervella et al. The mitogenome of a 35,000-year-old Homo sapiens from Europe supports a Palaeolithic back-migration to Africa. Nature 2016. Open access → LINK [doi:10.1038/srep25501]

Abstract

After the dispersal of modern humans (Homo sapiens) Out of Africa, hominins with a similar morphology to that of present-day humans initiated the gradual demographic expansion into Eurasia. The mitogenome (33-fold coverage) of the Peştera Muierii 1 individual (PM1) from Romania (35 ky cal BP) we present in this article corresponds fully to Homo sapiens, whilst exhibiting a mosaic of morphological features related to both modern humans and Neandertals. We have identified the PM1 mitogenome as a basal haplogroup U6*, not previously found in any ancient or present-day humans. The derived U6 haplotypes are predominantly found in present-day North-Western African populations. Concomitantly, those found in Europe have been attributed to recent gene-flow from North Africa. The presence of the basal haplogroup U6* in South East Europe (Romania) at 35 ky BP confirms a Eurasian origin of the U6 mitochondrial lineage. Consequently, we propose that the PM1 lineage is an offshoot to South East Europe that can be traced to the Early Upper Paleolithic back migration from Western Asia to North Africa, during which the U6 lineage diversified, until the emergence of the present-day U6 African lineages.

The interesting part is that today U6 is pretty much constrained to Northwest Africa and parts of Iberia and it has usually been considered until now as a North African haplogroup, even if of Eurasian derivation. 

Fig. 2 - (A) Phylogenetic analysis and temporal estimates for lineages including the Peştera Muierii-1 (PM1) from the mitochondrial tree. (B) Location of the Peştera Muierii cave and surface map based on current frequencies of U6 lineages³⁰; the European borders map was generated in ArcMap 10.1 (ESRI, http://www.esri.com) by modifying the World Borders Dataset (http://www.thematicmapping.org/downloads/world_borders.php), which is licensed under the Attribution-ShareAlike 3.0 Unported license. The license terms can be found on the following link: http://creativecommons.org/licenses/by-sa/3.0/ (This map was created by A.A.).

Another interesting bit is that U6(xU6a'b'd,U6c), U6* for short, is not known to exist today anymore. So it is reasonable to speculate about the "ancestral" position of Muierii in the lineage, regardless of whether Muierii-2 was a true ancestor or just a more or less distant relative of the real ancestor of modern day U6 carriers. 

Complementary information is to be found Secher et al. (2014), which refined the knowledge of the U6 mitochondrial haplogroup, unveiling that the key basal (and rare) U6c sublineage is not only found in Morocco (as known earlier) but also in Europe. Specifically U6c, which hangs directly from the U6 root node, is found in: Hispanic America (5.7% of all U6 carriers), Spain (2.2%), Canada (12.5%), NW Europe (16.7%), Morocco (4.5%), Algeria (10%) and Tunisia (5.9%). It is missing in Brazil, Western, Central and East Africa, Romani ("Gypsies"), Jews, Azores, Madeira, Canary and Cape Verde Islands, Portugal, Central and Eastern Mediterranean, West Sahara, Mauritania and USA (African-Americans,  European-Americans and Hispanics).

Figure 1

Surface maps, based on HVI frequencies (in o/oo), for total U6 (U6), total U6a (Tot U6a), U6a without 16189 (U6a), U6a with 16189 (U6a-189), U6b'd, U6c, U6b and U6d.

While the exact pattern of U6 expansion is not clear except for Africa (with a Moroccan origin surely), Sacher et al. believe that at least this part is related to the Iberomaurusian (aka Oranian) culture, which seems primarily an offshoot of Iberian Solutrean, also with origin in North Morocco (Taforalt) and European-like human looks (Cromagnoid).

Another complementary reference is Carmela L. Hernández et al. (2015):

An inspection of the U6 phylogenetic tree (S1 Dataset) showed that it is not easy to infer whether Iberia or North Africa bear more basal lineages. (...) The U6c (9.9 ky [5.0–15.0]) and U6d (12.0 ky [6.9–17.3]) are present in Iberia, Europe and North Africa at low frequencies.

While she seems to support a North African origin, the data is in fact somewhat contradictory:

Fig 5. Founder analysis for mtDNA U6 haplogroup. The plots show probabilistic distributions of U6 founder clusters for HVS-I sequences (A) and complete genomes (B) across migration times scanned at 200-year intervals from 0 to 60 ky.

Fig 7. Bayesian Skyline Plot (BSP) analysis of entire mtDNA U6 sequences.

Temporal changes of the effective population size, Ne in sub-Saharan Africa (brown color), North Africa (green color), and Iberian Peninsula (red color) are depicted. Solid lines represent the median values for the log10 of Ne on the Y-axis within each analyzed geographic region. The 95% HPD (highest posterior density) interval is shown for the three distributions (dashed lines).
Notice that the "LGM" label is very wrong: it should be around 21.000 years ago!

Usually U6 genetic history is envisioned as a migration from southwest Asia through North Africa [50]. This hypothesis is based on the general origin of haplogroup U sub-clades in Southwest Asia, which is also the center of the geographical distribution of U sub-clades: Europe, India, Central Asia, East Africa and North Africa. Two possible scenarios for the first U6 haplotype (bearing mutations 3348 and 16172) can be advanced: i) these mutations aroused in the founder region but did not leave any genetic legacy in current human populations there; ii) they originated probably somewhere in North Africa, after the arrival of the U6 founder haplotype. Within North Africa U6 is only significantly frequent at its western edge (as well as in South-western Europe). More importantly, all the most basal branches are virtually restricted to that region (U6b, U6c and U6d), what could indicate its western origin. Nevertheless, it cannot be excluded the major sub-clade U6a, which shows a richness of sub-clades in Northwest Africa [29] although a few of derivative branches also include sequences from East African and the Middle Eastern populations (e.g. U6a2).

Her conclusions (insisting on an African origin and first arrival via Egypt) are not something I can share at this stage of the research but her data is clearly very interesting and, combined with the rest, useful in discerning the possible route of primeval U6 to the Gibraltar Strait area, where it found no doubt its niche for consolidated expansion. 

After the Muierii finding the question is open: did primeval U6 arrive to North Africa via Iberia, being pruned in Europe afterwards just because of genetic drift and the sizable impact of Paleolithic migrations in low density areas? I cannot be 100% sure but I would say it is a very likely conclusion based not just on Muierii but also on the rather high basal diversity of U6 in Iberia (and surprisingly NW Europe!) and also on the archaeological data that makes almost necessary to root the first Upper Paleolithic of NW Africa (the Iberomaurusian) in the Iberian Solutrean.


(Special thanks to Jean Lohizun again).


Update (Jun 17):

The Hernández 2015 paper also mentions that  U6a1 appears to be of European and specifically Portuguese origin:

Our U6 tree built from mitogenomes shows that U6a1 is predominantly European because it contains a significant number of sequences of Mediterranean individuals mainly from the northwestern shore with a leading Iberian contribution (21 of the 29 European samples) and has an ancestral node in Portugal (accession number HQ651694).

Thanks to Geog M. for highlighting this important detail.

Most Africans do not have significant Eurasian admixture

This is major news: the authors of the study on the ancient East African genome of Mota have recanted their conclusions. In a correction note echoed by Nature they say:

Erratum'to'Gallego'Llorente'et'al.'2015'

The results presented in the Report “Ancient Ethiopian genome reveals extensive Eurasian admixture throughout the African continent“ were affected by a bioinformatics error. A script necessary to convert the input produced by samtools v0.1.19 to be compatible with PLINK was not run when merging the ancient genome, Mota, with the contemporary populations SNP panel, leading to homozygote positions to the human reference genome being dropped as missing data (the analysis of admixture with Neanderthals and Denisovans was not affected). When those positions were included, 255,922 SNP out of 256,540 from the contemporary reference panel could be called in Mota. The conclusion of a large migration into East Africa from Western Eurasia, and more precisely from a source genetically close to the early Neolithic farmers, is not affected. However, the geographic extent of the genetic impact of this migration was overestimated: the Western Eurasian backflow mostly affected East Africa and only a few SubUSaharan populations; the Yoruba and Mbuti do not show higher levels of Western Eurasian ancestry compared to Mota.

We thank Pontus Skoglund and David Reich for letting us know about this problem.

This makes much better sense admittedly. I strongly appreciate the willingness of Gallego, Jones et al. for publicly amending their wrong as quickly as possible. It's said that erring is human but correcting is only for the wise.

Algerian complex genetics

This is a rather interesting study that deals with the genetics of the Republic of Algeria, with several new samples.

Asmahan Bekada, Lara R. Arauna et al. Genetic Heterogeneity in Algerian Human Populations. PLoS ONE 2015. Open access → LINK [doi:10.1371/journal.pone.0138453]

Abstract

The demographic history of human populations in North Africa has been characterized by complex processes of admixture and isolation that have modeled its current gene pool. Diverse genetic ancestral components with different origins (autochthonous, European, Middle Eastern, and sub-Saharan) and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample. In order to evaluate the genetic heterogeneity of Algeria, Y-chromosome, mtDNA and autosomal genome-wide makers have been analyzed in several Berber- and Arab-speaking groups. Our results show that the genetic heterogeneity found in Algeria is not correlated with geography or linguistics, challenging the idea of Berber groups being genetically isolated and Arab groups open to gene flow. In addition, we have found that external sources of gene flow into North Africa have been carried more often by females than males, while the North African autochthonous component is more frequent in paternally transmitted genome regions. Our results highlight the different demographic history revealed by different markers and urge to be cautious when deriving general conclusions from partial genomic information or from single samples as representatives of the total population of a region.

Y-DNA frequencies

Supplementary Table 2: Y chromosome haplogroup frequencies among the studied populations (% in parentheses)
Population	Algiers1	Oran1	Reguibate1	Zenata1	Mozabite2	Oran3	Algiers4	Tizi Ouzou4
Abreviations	ALG1	ORN1	RGB	ZNT	MZB	ORN2	ALG2	TZO
Number of individuals	26	80	60	35	20	102	35	19
A -M91	(-)	1 (1.25)	(-)	(-)	(-)	(-)	(-)	(-)
C-M216	(-)	1 (1.25)	(-)	(-)	(-)	(-)	(-)	(-)
E1a-M33	1 (3.84)	(-)	(-)	1 (2.86)	(-)	(-)	1 (2.86)	(-)
E1b1a-M2	(-)	8 (10)	2 (3.33)	8 (22.86)	2 (10)	8 (7.84)	(-)	(-)
E1b1b1a-M78	4 (15.38)	2 (2.50)	(-)	1 (2.86)	(-)	6 (5.88)	4 (11.43)	(-)
E1b1b1b -M81	14 (53.85)	33 (41.25)	48 (80)	17 (48.57)	16 (80)	46 (45.10)	14 (40)	9 (47.37)
E1b1b1-M35	(-)	3 (3.75)	3 (5)	(-)	(-)	(-)	1 (2.86)	2 (10.53)
E2 -M75	(-)	1 (1.25)	(-)	(-)	(-)	(-)	(-)	(-)
F -M89 (xJ, K, Q, R1)	2 (7.69)	4 (5)	1 (1.67)	(-)	(-)	(-)	4 (11.43)	2 (10.53)
J -M304 (xJ2)	5 (19.23)	18 (22.50)	6 (10)	4 (11.43)	(-)	23 (22.55)	8 (22.86)	3 (15.79)
J2 -M172	(-)	1 (1.25)	(-)	(-)	(-)	5 (4.90)	2 (5.71)	(-)
K -M9	(-)	(-)	(-)	(-)	(-)	(-)	1 (2.86)	(-)
Q -M242	(-)	2 (2.50)	(-)	1 (2.86)	(-)	1 (0.98)	(-)	(-)
R1 -M173	(-)	6 (7.50)	(-)	3 (8.57)	2 (10)	13 (12.75)	(-)	3 (15.79)
Y Haplogroup Diversity GD (h +/- sd)	0.6677 +/- 0.0806	0.7674 +/- 0.0356	0.3520 +/- 0.0757	0.7092 +/- 0.0625	0.3579 +/- 0.1266	0.7245 +/- 0.0325	0.7782 +/- 0.0499	0.7427 +/- 0.0831
1 Present study
2 Shi et al. 2010
3 Robino et al. 2008
4 Arredi et al. 2004

The most common lineage is E1b-M81, which is centered around Morocco and has a mostly NW African distribution. The Reguibate sample (Arabic speakers from near Southern Morocco and West Sahara) shows extremely high frequencies (80%) of it. This is also true of the Mozabites. Otherwise the frequencies range between 40% and 54%.

Tropical African lineages are mostly represented by E1b-M2, which peaks among the Zenata Berbers of the Southern Atlas and Northern Sahara but has also some notable presence in Oran, Mozabites (North Sahara) and Reguibate (West Sahara). However these lineages are nearly absent in the Northeast Kabyle Berbers (Tizi Ouzu) and only have a token presence in Algiers (E1a). 

E1b-M78, a lineage centered in NE Africa, seems to peak in Algiers, with low frequencies in Oran and effectively absent in other populations. 

J1, presumably the same as J(xJ2), is strongest in the coast (Algiers, Oran) but has significant frequencies in other populations (excepted Mozabites). 

J2, although quite rare, is worth mentioning because its presence may indicate areas of true Arabic settlement (of course J1 is more common in Arabia but it is unthinkable that one goes without the other in such a recent time frame). It seems that Oran has the strongest such settlement, although some is also apparent in Algiers.

R1 peaks among Kabyles (16%) and is also present in Oran and among the Mozabite and Zenata Berbers. Sadly it is not analyzed what fraction of it is R1b-M412 (Western European) or R1b-V88 (Afro-Mediterranean), as both lineages have been detected in North Africa in previous studies but almost certainly have different histories. 

Other F is quite intriguing. The few Q and K* individuals are within expectations (at least my expectations) but there are a lot of F* people, notably in Kabyle and Algiers that are most intriguing. Are they within haplogroup G or is it something else? G reaches almost 10% in Egypt but previous studies had not found more than 6% in NW Africa (Bouhria Berbers, see here).

Update (Nov 4): Chris makes a very interesting suggestion in the comments section about all this F*: what if it is (partly or in full) haplogroup I, a typical European Y-DNA lineage that is clearly rooted in the Paleolithic of the region? The lineage has been documented in ancient Berbers from Canary Islands and, for what Chris says, also in Sudan. It would make perfect sense if it was also present among modern NW Africans, being consistent with other genetics that seem to originate in Paleolithic Europe (~30% of mtDNA, a good share of autosomal DNA, maybe also part of the Y-DNA R).

Mozabites are close to "pure North Africans"

Autosomal analysis shows that this Berber population of the Algerian Atlas has the lowest range of admixture form any external source, be it Europe, West Asia or Tropical Africa. Some individuals appear extremely unadmixed.

Fig 3. Plots for the analysis of genome-wide SNPs.

PC analysis (upper figures) based on autosomal data, and X-chromosome SNPs. ADMIXTURE proportions (bottom figures) at k = 2,3, and 4 based on autosomal data and X-chromosome SNPs. Algeria, stands for general Algerian sample [3]; Mozabite, stands for the Algerian Berber Mozabites [32]; and Zenata, stands for Algerian Berber Zenata (present study).

X-chromosome conundrum

It is not common that genetic studies analyze the X-chromosome. A reason is probably that its interpretation can be confusing. Intuitively it seems true that the X chromosome is passed down by a mostly female line but this is not really correct, as (ignoring partial recombination) a man can have an X chromosome from either the maternal grandfather or grandmother, while a woman will have one from her father and another from the mother. Ironically only a woman's father-inherited X-chromosome can be automatically traced to a woman two generations back: that of the paternal grandmother. Complicated, right?

As probably apparent in fig. 3 above but made more clear in fig. 4 below, the study detected differences in autosomal (overall) ancestry and X-chromosome one.

Fig 4. Correlation plots of the ancestry proportions at k = 4 in the ADMIXTURE analysis comparing autosomes and X-chromosome SNPs.

North African, sub-Saharan, Middle Eastern, and European ancestry proportions are shown in different plots. Solid black lines represent linear correlations between autosomal and X-chromosome components.

The authors interpret these results as indicating female bias in the European and West Asian components. This may be true at least in the European case because it correlates well with the differential between European mtDNA (~30%) and Y-DNA (<10%), which suggests that European ancestry used to be more important in the past and that male-biased migrations (Capsian culture is probably one of the culprits) altered this. 

But is it also true for the West Asian ancestry? I can't say, really. I remember a study from a decade ago (don't have the reference right now, sorry) or so that showed that in a Colombian coastal town, X-chromosome ancestry was almost only European, while mtDNA was instead almost exclusively Native American, and that it should be interpreted as continuous influx of men from Europe, marrying local women, who managed to retain, generation after generation, the aboriginal mtDNA (which does never leave the strict maternal line) but not the X-chromosome line, once and again altered by male immigrants. 

I don't really dare to subscribe the authors' interpretation without a more nuanced analysis, analysis that I don't feel able to perform myself at the moment either. If they are correct, anyhow, it means that there were important male-biased demographic expansions of African specific origin, either in NW Africa itself (what could well be supported by the vigor of E1b-M81) or in NE Africa prior to migration to the West within Capsian. Or both. 

Mitochondrial DNA data

In case anyone wants to try their luck at this complicated analysis (North Africans are indeed a complex and most intriguing population), I'm adding here the raw mtDNA table:

Supplementary Table 5: mtDNA haplogroup frequencies (%) distribution among Algerian populations
Populations	Algiers	Oran	Zenata	Reguibate	Oran (Bekada et al. 2013)	Mozabite (Corte-Real et al. 1996)
Abbreviation	ALG	ORN1	ZNT	RGB	ORN2	MZB
Number of samples	62	93	73	108	240	85
H/HV	19.35	35.48	12.33	30.56	30.83	23.53
HV0	4.84	2.15	5.48	6.48	3.75	8.24
I	1.61	-	1.37	-	0.83	-
J (16069 16126)	14.52	3.23	2.74	0.93	3.33	3.53
K (16224 16311)	-	4.30	4.11	3.70	1.67	-
L	-	-	-	0.93	-	-
L0	1.61	3.23	1.37	-	0.42	-
L1b	1.61	2.15	9.59	6.48	3.75	-
L1c	-	-	1.37	0.93	0.83	-
L2	-	-	5.48	4.63	0.83	-
L2a	9.68	5.38	15.07	3.70	5.42	5.88
L2b	1.61	2.15	5.48	-	0.42	1.18
L2c1	-	-	1.37	-	1.25	-
L2d	-	-	-	1.85	-	-
L2e	-	1.08	-	-	-	-
L3b	1.61	3.23	2.74	3.70	1.67	2.35
L3b/d	-	-	4.11	-	-	1.18
L3d	-	-	4.11	-	1.25	-
L3e1	1.61	-	-	-	0.42	-
L3e2	4.84	-	5.48	-	0.83	2.35
L3e3	1.61	-	-	-	-	-
L3e5	11.29	-	-	-	0.42	-
L3f	-	4.30	8.22	3.70	2.08	-
L3h1b1a	1.61	-	1.37	-	-	-
L4b2	-	-	-	-	0.42	-
M1	3.23	5.38	-	1.85	7.08	4.71
N	1.61	1.08	-	0.93	0.42	-
R	-	-	-	0.93	-	-
R0a	-	-	-	0.93	1.67	-
R0a1a	-	-	-	8.33	-	-
T*	-	-	-	0.93	1.67	-
T1a	1.61	2.15	2.74	-	3.33	4.71
T2	-	1.08	-	0.93	0.42	-
T2b	-	-	2.74	-	2.92	-
T2c	-	-	-	-	0.83	-
U	-	1.08	-	0.93	0.42	-
U1	-	1.08	-	0.93	0.83	-
U3	-	1.08	-	-	1.25	10.59
U4	1.61	-	-	-	1.67	1.18
U5	-	-	-	-	0.42	-
U5a	1.61	3.23	-	-	1.67	-
U5b	1.61	1.08	-	2.78	0.42	-
U6a	-	4.30	-	7.41	6.67	-
U6a1a	-	1.08	-	-	-	12.94
U6a1a1	-	3.23	-	3.70	-	14.12
U6a1b	-	1.08	-	-	-	1.18
U6a5	-	-	-	-	0.83	-
U6c	-	-	1.37	-	0.83	-
U8b1	-	1.08	-	-	-	2.35
V	-	-	-	-	3.75	-
V7a	-	1.08	-	1.85	-	-
W	3.23	1.08	-	-	1.25	-
X	8.06	2.15	-	-	-	-
X2	-	1.08	1.37	-	1.25	-
mtDNA haplogroup diversity (h+-sd)	0.9175 +/- 0.0174	0.8630 +/- 0.0325	0.9376 +/- 0.0117	0.8823 +/- 0.0236	0.8853 +/- 0.0166	0.8891 +/- 0.0169

 

Good luck (and feed me back if you have some idea).