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Genomic Ancestry of North Africans Supports Back-to-Africa Migrations Brenna M. Henn
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[QUOTE]Originally posted by xyyman: [QB] After re-reading this paper I have to admit this is much to do about nothing. It is all extreme speculation. Almost laughable. In fact the title is mis-leading and written out of context of what is documented in the paper. I guess it was titled like most things these days with the intent to create controversy and draw attention. The conclusion section says it all. The authors don’t really believe this back-migration nonsense. See highlighted sections. Note their non-African reference population- Basque and Qatari. I needed to read this several times to get it. Some of you may understand. But let me break it down. Please read and understand before replying. Sage, Swenet..maybe Lioness..others give me some feedback. Key things that jump out at you. 1. Tunisian Berbers are 100% pure indigenous. Minor “recent” near east input in other groups. 2. They used an “outlier” reference populations. Basque that are known to have Berber admixture. And Qatari which is on the other side of the Arabian peninsular. 3. The admit the result is inconclusive. They recommend that ….STR!!!…studies be performed to confirm their speculation. STRs were posted by me already. 4. They are suggesting that the Qatari came from a similar but DIFFERENT source population. 5. They are suggesting that the Berber ancestral population left Africa spent ~1Kyrs in Arabia returned to Africa for another 38-40,000yrs!!! That is like someone spending first 25yrs of their life in one city, left and spent 1 yr in the neighboring city, then returned to their home town and spent another 40yrs. Does that make them non-African? 6. They confirmed there were NO migration from the Middle-East since then ie that initial OOA, short stay and back. 7. They confirmed a decreasing West to East gradient of genetic material. Nothing new here. 8. They confirmed the initial ancestral source MAY be along the Nile. No Shyte!! Can anyone say E1b1b or Sergi. 9. They admit other Africans were in the North Africa since 65,000ya. As posted by Troll Patrol, Hublin et al. Yet they BS!! LOL! [i] Genomic Ancestry of North Africans Supports Back-to-Africa Migrations Brenna M. Henn1 Prior genetic studies, largely from uniparentally inherited markers(ie Haplogroups), have not resolved the location origin of North African populations or the timing of human dispersal(s) into North Africa. Analyses based on the frequencies of a small number of autosomal genetic polymorphisms(ie SNPs) and uniparental markers(ie Haplogroups) have shown that the genetic landscape follow an east-west pattern with little to no difference between Berber- and Arab-speaking populations [6,7]. Initial autosomal SNP analysis of the Algerian Mozabites indicated they carry ancestry from Europe, the Near East and sub-Saharan Africa; neighbor-joining phylogenetic analysis suggested that [b]Mozabites[/b] branch off with Out-of-African populations, but [b]are an outgroup to all Near Eastern populations [/b]in the Human Genome Diversity Panel (HGDP-CEPH) [17]. In short, the origins of North African populations and the number of subsequent migrations from neighboring regions have been poorly resolved. there is a cline of putative[b] autochthonous North African ancestry decreasing in frequency from Western Sahara eastward to Egypt. [/b]We refer to this North African ancestral component as the ‘‘Maghrebi’’ throughout the remainder of the paper, reflecting the primary geographic distribution of this ancestry in the Maghreb: West Sahara, Morocco, Algeria and Tunisia. [b]The west-to-east decline in Maghrebi assignment is only interrupted by the Tunisian Berbers, who are assigned nearly 100% Maghrebi ancestry. [/b]The Tunisian Berbers further separate as a distinct population cluster at k=8. [b]An opposite cline of ancestry appears to originate in the Near East (i.e. Qatari Arabs) and decreases into Egypt and westward across North Africa (k= 6, 8).[/b] Islam!! Discussion Out of Africa and Back Again? By sampling multiple populations along an approximate transect across North Africa, we were able to identify gradients in ancestry along an east-west axis [b]We can reject a simple model of long-term continuous gene flow between the Near East and North Africa[/b], as evidenced by clear geographic structure [b]After accounting for putative recent admixture (Figure 1), the indigenous Maghrebi component (k-based) is estimated to have diverged from Near Eastern/Europeans between 18–38 Kya[/b] (Figure 3), under a range of Ne and k values. We hence suggest that the ancestral Maghrebi population separated from Near Eastern/Europeans prior to the Holocene, and that the[b] Maghrebi populations do not represent a large-scale demic diffusion of agropastoralists from the Near East.[/b] No shyte!! With model parameters for divergence approximately estimated, we then ask whether North African ancestral populations were part of the initial OOA exit and then returned to Africa [8], or if an in situ model of population persistence for the past 50 Kya is more likely (with variable episodes of migration from the Near East)? [b]We can address this question only indirectly with contemporary samples[/b]; however, several auxiliary observations point toward the [b]former hypothesis. [/b] [b]In contrast, we find it more parsimonious to describe model where: a) an OOA migration occurs [concurrent with a bottleneck]; b) OOA populations and North Africans diverge between 12–40 Kya when a migration back-to-Africa occurs.[/b] *****These models should be further tested with genomic sequence data, STRs!! which have better power to detect magnitude and timing of bottlenecks, and to estimate the true joint allele frequency spectrum. ****The less than[b] 25% European ancestry in populations like Algerians and northern Moroccans could trace back to maritime migrations [/b]throughout the Mediterranean [34]. Alternatively, the [b]Qatari could represent a poor proxy for an Arabic source population,[/b] causing additional diversity to be assigned European (e.g. European ancestry tracts were not reliably assigned as European with PCADMIX). [b]In summary, although paleoanthropological evidence has established the ancient presence of anatomically modern humans in northern Africa prior to 60,000 ya [/b][35], the simplest interpretation!!!!!! of our results is that the majority of ancestry in modern North Africans derives from populations outside of Africa, through at least two episodes of increased gene flow during the past 40,000 years (Figure 1, Figure 2, Figure 3). Materials and Methods Samples and Data Generation A total of 152 individuals representing seven different North African locations and the Basque Country were included in the present study. Informed consent was obtained from all of them. Samples were genotyped on the Affymetrix 6.0 chip, and after quality control filtering for missing loci and close relatives, [b]125 individuals remained: 18 from North Morocco, 16 from South Morocco, 18 from Western Sahara, 19 from Algeria, 18 from Tunisia, 17 from Libya and 19 from Egypt. Further information on the samples may be found in Table S1. Moreover, 20 individuals from the Spanish Basque country were included in the analysis.[/b] Data are publicly available at: bhusers.upf.edu/dcomas/. In order to study the population structure and the genetic influence of migrants in the region a database was built including African and European populations from HapMap3 [43], western Africa [20], and [b]20 Qatari from the Arabian Peninsula [44] as Near Eastern representatives.[/b] [/i] [/QB][/QUOTE]
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