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[QUOTE]Originally posted by the lioness,: [QB] commentary about Ancient Mummy Genomes article. I find the title of the article to be dumb but there is some interesting commentary below " But ultimately what’s great about this paper is that they have ancient autosomal DNA. That is, genome-wide results." __________________________________________________ https://gnxp.nofe.me/2017/05/30/ancient-egyptians-black-or-white/ excerpt: [b]Ancient Egyptians: Black Or White?[/b] POSTED ON MAY 30, 2017 BY RAZIB KHAN Gene Expression [IMG]http://gnxp.nofe.me/wp-content/uploads/2017/05/egyptmtdna.jpg[/IMG] Because modern people care about the Afrocentrist question, the extent of Sub-Saharan African ancestry is highlighted in this paper. I do not think this is actually the most interesting aspect. But I’ll get to that. Since this post will be read by a fair number of people I’ll talk about the relationship of ancient and modern Egyptians to (Northern) Europeans and Sub-Saharan Africans. The figure to the left is looking at 90 ancient Egyptian mitochondrial genomes (and some modern ones in the two rightmost columns). Since mtDNA is copious it was relatively easy to extract and analyze. Haplogroup L, the red to orange shades in the bar plots, are associated without dispute with Sub-Saharan Africa. Haplogroup U6, M1 and a few others may be “back to Africa” variants of different periods (they are generally found in Afro-Asiatic groups). What you can see is that somewhat more than half of Ethiopia’s mtDNA lineages are L, in keeping with the whole genome estimate of Sub-Saharan African ancestry in most Cushitic populations. In Egypt there is a difference over time; haplogroup L goes from low frequencies to much higher frequencies in modern periods. The ~20% fraction in the modern samples is in line with the population wide admixture one sees in modern Egyptians of Sub-Saharan admixture. I actually recomputed the haplogroups to a finer granularity from the supplements. A quick inspection of mtDNA haplogroup frequencies shows that ancient Egyptians are not typical of modern Europeans. Not that much H, and lots of T, J and K. What that does remind me of are Early European Farmers. These people, who brought agriculture to Europe from Anatolia contributed a large fraction of the ancestry of modern Southern Europeans, and a lesser component to Northern Europeans. [IMG]http://gnxp.nofe.me/wp-content/uploads/2017/05/egyptbar.jpg[/IMG] [b]But ultimately what’s great about this paper is that they have ancient autosomal DNA. That is, genome-wide results.[/b] They got three samples of reasonably high quality. More precisely: “Two samples from the Pre-Ptolemaic Periods (New Kingdom to Late Period) had 5.3 and 0.5% nuclear contamination and yielded 132,084 and 508,360 SNPs, respectively, and one sample from the Ptolemaic Period had 7.3% contamination and yielded 201,967 SNPs.” You can see the three samples on this bar plot. What is interesting is that they’re all pretty similar. What you can see here is that to a great extent ancient Egyptians were descended from a population closely related to Natufians, or Natufians themselves. This easily explains the mtDNA affinity to Neolithic farmers: Natufians and Anatolian Neolithic populations were sister populations. The f3 statistic which looks at shared drift shows an affinity of ancient Egyptians with ancient farmer populations with Near Eastern provenance, but also with modern Sardinians. This is a common pattern, as ancient groups do not have later migration waves, with the Sardinians the modern population closest to this. You see in the bar plot that northern Levantine populations are placed between Anatolian Neolithics and Natufians, as one might expect based on their geographical position and gene flow between these two regions. Additionally, the cyan color is associated with eastern farmers from the Zagros. I’ve already talked about gene flow from this area to the Levant recently. If you compare the Bronze Age Sidon samples I think you’ll see broad affinities with these Late Period Egyptians. [IMG]https://www.nature.com/article-assets/npg/ncomms/2017/170530/ncomms15694/images/m685/ncomms15694-f4.jpg[/IMG] The PCA gives us results consonant with the model-based clustering. If you plot the genetic variation of ancient Egyptians they’re closest to Neolithic eastern Mediterranean populations. No great surprise. Not the modern Egyptians. Why? It’s pretty clearly because modern Egyptians are shifted toward Sub-Saharan Africans. But there is also another component: modern Egyptians have more of the cyan eastern farmer component. What could this be? An immediate thought comes to mind. We focus a great deal on Sub-Saharan African slavery. One reason is that it is visible. Black Africans are physically distinct from most Middle Eastern populations. But Egypt was long the center of another slave trade: “white slaves” from the Caucasus. Circassians. For hundreds of years Mamluks were recruited from the Caucasus as military slaves. They eventually became the ruling class of Egypt, until their decimation in the 19th century under Muhammad Ali (who himself was an Albanian Ottoman who never learned to speak Arabic well). As noted in the paper earlier work looking at patterns in ancestry tracts and LD decay had made it obvious that much of the admixture of Sub-Saharan ancestry in Egypt, as in much of the Middle East, is relatively recent. In particular, it dates to the Islamic period, when trade and conquest took on new dimensions in Africa and north into Central Asia. One way ethnic minorities like Assyrians and Lebanese Christians differ from their Muslim neighbors is that they have much lower fractions of Sub-Saharan African ancestry, and no East Asian component. The latter might surprise, but remember that Central Asian Turkic slaves have been prominent in Muslim armies since at least the 9th century. But some of the Sub-Saharan ancestry in Egyptians is old. The ancient Egyptian samples have it. To have none of it would seem strange, considering the history of contact between Nubia and Egypt, dating back to the Old Kingdom. Second, there is evidence of low levels of Sub-Saharan African gene flow into Southern Europeans. How did that happen? The highest fractions are in Spain, and can there be attributed to the Moorish period. But that explanation does not hold in much of Italy, where there are a few percent of haplogroup L. This probably is due to south-to-north gene flow across the Mediterranean during the Classical period. Some of the peoples on the south shore of the Mediterranean almost certainly already had some Sub-Saharan African admixture. [IMG]http://gnxp.nofe.me/wp-content/uploads/2017/05/f4.jpg[/IMG] Not getting into the details of it, there are ways to explicitly model gene flow into a target population from donors defined by a phylogeny. In this case the authors tested various models of gene flow from Sub-Saharan Africans and Eurasians (non-Africans) to generate allele frequency patterns we see in modern Egyptians and ancient Egyptians. What they consistently found is that modern Egyptians are about twice as much Sub-Saharan African as ancient Egyptians. The proportions for modern Egyptians ranged from ~10 to ~20 percent Sub-Saharan African against a Eurasian background, with a bias toward the higher values (depending on which populations you put into the phylogeny for non-Africans), and ~0 to ~10 percent for the ancient Egyptians, again with a bias toward the higher values. The pattern is consistent in these tests. An issue here is that we’re going off three samples. That being said, the authors observe that despite differences in contamination/quality and time period they’re very concordant with each other. If I had to bet I think Old Kingdom samples would have somewhat less Sub-Saharan and eastern farmer ancestry. But the basic pattern persisted down to the Roman period, and was only shifted by admixture due to slavery. [IMG]http://gnxp.nofe.me/wp-content/uploads/2017/05/srep09996-f3.jpg[/IMG] And not to belabor the point, but a paper from a few years ago which had some Copt samples looks familiar in its broad outlines. You see that the Copts have very little Sub-Saharan African ancestry, though it does seem to be evident (the marker set is in the hundreds of thousands of SNPs). Additionally, they are quite distinct from the Qatari Arab sample. Unfortunately the data for this paper just published is not on the European Nucleotide Archive. I really want to dig a little deeper into it. What are the takeaways here? Egypt has been the sink for a lot of migration and gene flow over the past several thousand years, and probably earlier. Not surprising considering that it was relatively wealthy in the aggregate. The Natufian population that the Late Period Egyptians resemble the most did not have Sub-Saharan African ancestry according to earlier research. These Late Period Egyptians do have some. This is reasonable in light of the long interaction with Nubia which is historically attested. Similarly, there was clearly gene flow from Southwest Asia. This is again historically attested, especially in the Nile Delta (though foreign garrisons of mercenaries are recorded in Upper Egypt as well). The Roman period probably did introduce some gene flow from Southeast Europe and Southwest Asia. But these populations are not that distinct from Egyptians. Similarly, the Islamic period also brought in different peoples from Arabia and the Caucasus. But the most salient dynamic during the Islamic period was a massive trans-Saharan slave trade (though the Caucasus impact may have been comparable, and I think these results support the proposition that it was). It seems entirely likely that the Copts are descended from a mix of Roman era Egyptians. Not only do they resemble the people in the Fayum portraits, but the circumstantial genetic data is that they have fewer “exotic” components which increased in frequency during the Islamic era. This would be exactly parallel to ethno-religious minorities in the Levant and Iraq. One curious element to me is the suggestion gene flow before ~5,000 BCE between Sub-Saharan Africa and the lower Nile valley was low. If it hadn’t been low, it seems unlikely that the fraction of Sub-Saharan ancestry (or shift in that direction in relation to other Eurasians) in Copts would be so small. So what explains the lack of earlier gene flow? I think the answer is going to be the fact that the human demographic landscape is characterized by lots of local population extinctions. As ancient DNA sampling coverage gets better and better meta-population dynamics are coming into focus, and we see gene flow, and die offs, in several areas. It is fashionable to say that human population variation is characterized by clines. But much of this clinal aspect is an outcome of the period after massive admixture over the last ~10,000 years. And yet it may not be that the period before the Holocene was not clinal. Rather, it may be that large depopulations of areas of human occupation fragmented clinal ranges, and resulted in new range expansions from “core” zones. About ~8,000 years ago there was a major desertification period in the Sahara desert. Many trans-Saharan populations may have gone extinct during this time due to rapid climate change. Eventually repopulation may have occurred from outside of the Sahara, so that post-Natufian Levantines and Sub-Saharan Africans from what today call the Sahel pushed up and down the Nile drainage basic respectively, meeting in the zone of Nubia on the boundary of history and prehistory. Unlike many other areas of the world we have a long attested record of Egyptian history. As we get more mummy samples it seems likely that we’re get a crisper, clearer, picture. And the time transects will not be narrative blind; we already know the general arc of Egyptian history. If, for example, we see a new ancestral component around ~1500 B.C., in Egypt it’s not mysterious what this might be: the Hyksos. This is just the prologue to a fascinating book that will be written over the next decade. [/QB][/QUOTE]
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