December 23, 2013

Recent origin of North African populations

This makes sense since North Africans are so close (phenotypically) to West Eurasians that it makes sense that they cannot have been isolated from them for very long, i.e., since Out-of-Africa.

PLoS ONE 8(11): e80293. doi:10.1371/journal.pone.0080293

Genome-Wide and Paternal Diversity Reveal a Recent Origin of Human Populations in North Africa

Karima Fadhlaoui-Zid, Marc Haber et al.

The geostrategic location of North Africa as a crossroad between three continents and as a stepping-stone outside Africa has evoked anthropological and genetic interest in this region. Numerous studies have described the genetic landscape of the human population in North Africa employing paternal, maternal, and biparental molecular markers. However, information from these markers which have different inheritance patterns has been mostly assessed independently, resulting in an incomplete description of the region. In this study, we analyze uniparental and genome-wide markers examining similarities or contrasts in the results and consequently provide a comprehensive description of the evolutionary history of North Africa populations. Our results show that both males and females in North Africa underwent a similar admixture history with slight differences in the proportions of admixture components. Consequently, genome-wide diversity show similar patterns with admixture tests suggesting North Africans are a mixture of ancestral populations related to current Africans and Eurasians with more affinity towards the out-of-Africa populations than to sub-Saharan Africans. We estimate from the paternal lineages that most North Africans emerged ~15,000 years ago during the last glacial warming and that population splits started after the desiccation of the Sahara. Although most North Africans share a common admixture history, the Tunisian Berbers show long periods of genetic isolation and appear to have diverged from surrounding populations without subsequent mixture. On the other hand, continuous gene flow from the Middle East made Egyptians genetically closer to Eurasians than to other North Africans. We show that genetic diversity of today's North Africans mostly captures patterns from migrations post Last Glacial Maximum and therefore may be insufficient to inform on the initial population of the region during the Middle Paleolithic period.



Charles said...

That would go well with what I have discovered from my own genome. I have nearly 1% of Denisovan, and my family has the South Asian Indian phenotype. So The Berbers (including the survivors of the inhabitants of the Canaries) seem to be (at least on the male side for sure) the product of a back migration to Africa from Eurasia some time at the end of the Pleistocene.

Unknown said...

Some little gems from this paper:

Figure 3 appears to show that modern North Africans do not descend directly from a Middle Eastern population. Rather the Levant and North Africa are brother groups from an older population roughly represented by Basques and Italians. I imagine this group was the original early Mediterraneans.

"Although recent cultural expansions from the Middle East, like the Islamic expansion, could have introduced new lineages to North Africa and facilitated admixture between populations from both regions, our results show that the North African component mostly formed much earlier. "


"Although most North Africans appear as an admixture of populations from the surrounding regions, the Tunisian Berbers show long periods of genetic isolation, allowing a distinctive genetic component to evolve. Unlike other North Africans, our admixture tests propose that Berbers diverged from surrounding populations without subsequent mixture. We show that coalescence time estimate from paternal lineages are pushed back ~15,000 years when Tunisians (Berbers and general population) are included in the analyses suggesting an early upper Paleolithic ancestral population with most North Africans (~30,000–44,000 ya)."

So it looks like modern North Africans are mostly (southern) European with a recent Islamic and sub-saharan African contributions. Plus there is a very, very old uniquely North African component. IMO.

Charles said...

I would agree with the "uniquely old North African" comment. Isolated peoples that still exist in North West Africa and the remainder of the Aboriginals in the Canaries still have traces of the cro magnon features that once predominated that area.