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Recent genetic study on the Druze populace.
Reconstructing Druze population history[/SIZE][/B]
Scarlett Marshall,1 Ranajit Das,2 Mehdi Pirooznia,3 and Eran Elhaika,4
Sci Rep. 2016; 6: 35837.
Published online 2016 Nov 16. doi: 10.1038/srep35837
The Druze are an aggregate of communities in the Levant and Near East living almost exclusively in the mountains of Syria, Lebanon and Israel whose ~1000 year old religion formally opposes mixed marriages and conversions. Despite increasing interest in genetics of the population structure of the Druze, their population history remains unknown. We investigated the genetic relationships between Israeli Druze and both modern and ancient populations. We evaluated our findings in light of three hypotheses purporting to explain Druze history that posit Arabian, Persian or mixed Near Eastern-Levantine roots. The biogeographical analysis localised proto-Druze to the mountainous regions of southeastern Turkey, northern Iraq and southeast Syria and their descendants clustered along a trajectory between these two regions. The mixed Near Eastern–Middle Eastern localisation of the Druze, shown using both modern and ancient DNA data, is distinct from that of neighbouring Syrians, Palestinians and most of the Lebanese, who exhibit a high affinity to the Levant. Druze biogeographic affinity, migration patterns, time of emergence and genetic similarity to Near Eastern populations are highly suggestive of Armenian-Turkish ancestries for the proto-Druze.
The population history of the Druze people, who accepted Druzism around the 11th century A.D., remains a fascinating question in history, cultural anthropology and genetics. Contemporary Druze comprise an aggregate of Levantine and Near Eastern communities residing almost exclusively in the mountain regions of Syria (500,000), Lebanon (215,000), Israel (136,000) and Jordan (20,000), although with an increasingly large diaspora in the USA1,2,3. Almost half of the total population of Druze live on Mount Hauran, alternatively known as Jabal al-Durūz, or the Mountain of the Druze, south of Damascus. The remainder live in the Lebanese Mounts Lebanon and Shuf and the Israeli Mount Carmel, Golan Heights and the Upper Galilee region. Shortly after its modest beginnings in the early 11th century A.D.
More recent studies have reported that the Druze share many genetic characteristics with other Levantine populations (i.e., Palestinians and Bedouins) compared to Europeans and Central or South Asians e.g.15,16,17,18. However, these studies have focused on the ancestry of the Druze, relying mostly on principle component (PC) and structure-like analyses, which have major limitations19,20 and are unsuitable to biogeography10. Diffused Southern Turkish and Northern Syrian origins were recently proposed for the Druze using a PC-based application for biogeography21.
Like most Eurasians, the Druze genomes exhibit a mixture of three major components: Mediterranean (An external file that holds a picture, illustration, etc. Object name is srep35837-m1.jpg), Southwest Asian (An external file that holds a picture, illustration, etc. Object name is srep35837-m2.jpg) and Northern European (An external file that holds a picture, illustration, etc. Object name is srep35837-m3.jpg) (Fig. 1). Druze and Syrians possess a significantly larger amount of the Northern European component (An external file that holds a picture, illustration, etc. Object name is srep35837-m4.jpg) when compared with their neighbouring populations, such as Palestinians (An external file that holds a picture, illustration, etc. Object name is srep35837-m5.jpg) and Lebanese and Bedouins (An external file that holds a picture, illustration, etc. Object name is srep35837-m6.jpg) (Kolmogorov-Smirnov goodness-of-fit tests, [Syrians] p-value < 0.05, [Palestinians] p-value < 10−10, [Lebanese and Bedouins] p-value < 10−11). Using Alder26 we found that there is evidence for admixture in Druze between the early 9th century and the early 12th century (38.62 ± 5.8 generations ago). This estimate is within the range proposed by two recent studies using the less accurate ROLLOFF26 (46 ± 5)18 and CHROMOPAINTER (31.64 ± 4 generation
A comparison of the genetic distances between the Druze and the reference populations (Figure S2) confirmed that Druze individuals exhibit the shortest genetic distances to Syrians (31%), Palestinians (31%) and Lebanese (24%) followed by Armenians (12%) and Saudis (2%). To illustrate the genetic distances between Levantine individuals, we plotted the genetic distances between Druze, Syrians and Palestinians (Fig. 4). Surprisingly, we found a Druze individual (HGDP00576) whose admixture signature resembled a Palestinian one, likely due to a very recent gene exchange event.
GPS localised Syrians to Syria (An external file that holds a picture, illustration, etc. Object name is srep35837-m15.jpg, An external file that holds a picture, illustration, etc. Object name is srep35837-m16.jpg) even after excluding the Syrian from the reference population panel (An external file that holds a picture, illustration, etc. Object name is srep35837-m17.jpg, An external file that holds a picture, illustration, etc. Object name is srep35837-m18.jpg) (Fig. 3[B1,B2]). Only 6–12.5% of the Syrians were localised to the Lake Van region (Fig. 3[B1,B2]). The Palestinians were also highly localised to North Israel, West Jordan and Syria (An external file that holds a picture, illustration, etc. Object name is srep35837-m19.jpg, An external file that holds a picture, illustration, etc. Object name is srep35837-m20.jpg) (Fig. 3[C1,C2]). While 36% of the Lebanese clustered in Syria, most of the Lebanese (45%) were localised along a trajectory parallel to the Incense Route leading from South Arabia to the Mediterranean (Fig. 3[D1]). Excluding Syrians, their closest population, supported a primarily Arabian root for the Lebanese and secondarily Syrian (Fig. 3[D2]). None of the Lebanese clustered close to Lake Van with only 6% in central Turkey. The Bedouins clustered in Israel, Jordan, Egypt and Saudi Arabia, as would be expected from their pastoral and nomadic history (Fig. 3[E1,E2]).
Our biogeographical analyses highlight the high genetic similarity between Druze and Near Eastern populations, compared with Levantine populations who were predicted close to each other and some of the Druze. This is in agreement with an ancient DNA study28 where Druze clustered with few Lebanese, close to a Chalcolithic Anatolian and Chalcolithic/Bronze Age Armenians, and away from Levantine populations who clustered with Neolithic/Bronze Age Levantines. To obtain further insights into the population structure of Druze and Levantine populations in relation to ancient populations, we carried out a supervised admixture analysis using ancient Levantine, Armenian, and Anatolian individuals dating to the Neolithic, Chalcolithic and Bronze Age periods as ancestral populations. A third of the Druze and Bedouins show complete Armenian and Levantine ancestries, respectively. The remaining genomes exhibit a mixture of the three ancestries (Fig. 5). Interestingly, Druze possess a significantly larger amount of ancient Armenian ancestry (An external file that holds a picture, illustration, etc. Object name is srep35837-m21.jpg) compared to other Levantine populations (21.12% < An external file that holds a picture, illustration, etc. Object name is srep35837-m22.jpg) (Kolmogorov-Smirnov goodness-of-fit tests, [modern-day Levantine populations] p-value < 10−25). Druze also have a significantly smaller ancient Levantine ancestry (14.9%) compared to other Levantine populations (36.07% < An external file that holds a picture, illustration, etc. Object name is srep35837-m23.jpg) (Kolmogorov-Smirnov goodness-of-fit tests, [modern-day Levantine populations] p-value <10−25). The ancient Anatolian component distributes nearly evenly (18–22%) among mixed Levantine individuals and exhibits a gradient in Druze (0–17%). These results are in agreement with our findings using modern-day populations that indicated a high similarity between Druze and Near Eastern populations over Levantine populations and the complex population structure of the Druze (Fig. 3[A2]), which is distinct from that of Levantine populations (Fig. 5).
Although predicted in part to Syria (Fig. 3[A1]), like Palestinians, Lebanese and Syrians (Fig. 3[B–D]), only a minority of the Druze (Fig. 3[A2]) could be considered to be highly localised to the Levantine. The mixed population structure of the Druze has two biogeographical affinities: a southeast Turkish-northern Iraqi one overlapping the Zagros Mountains and close to Mount Ararat and a southeast Syrian one, close to Mount Hauran. Though the Turkish affinity of the Druze can be observed for a smaller fraction of Druze, likely due to on-going gene exchange with Syrians (Fig. 3[A1]), it can still be recognised as the primary affinity of nearly 80% of Druze (Fig. 3[A2]), suggesting its antiquity compared to the Syrian affinity. Such a conclusion is in agreement with our ancient DNA analysis since, in relation to ancient individuals (12,000–1000 B.C.), a third of the Druze appear like ancient Armenians, whereas the remaining exhibit nearly 80% ancient Armenian ancestry compared to less than 15% ancient Levantine ancestry (Fig. 5). Altogether these findings suggest that the proto-Druze were from tribes who resided around the Zagros and surrounding mountains and Syrian tribes with whom they exchanged genes (Fig. 3[A1]) subsequent to, and after, their migration to Palestine. We speculate that the gene exchange events with non-Druze were uneven across the population, which helped retain some of the Near Eastern admixture signature that distinguishes Druze from other Levantine populations (Figs 3[A2–E2] and and5).5). Consequently, the majority of Druze are genetically closer to Syrians than to other Levantine populations (Fig. 4) and share a genetic similarity with Arabians as well as Near Eastern populations (Figure S2). These results are in agreement with those of Elhaik21, reporting Southern Turkish and Northern Syrian biogeographical affinities in support of the Near Eastern hypothesis for the emergence of Druze over alternative hypotheses that fail to explain the mixed biogeographical affinities of the Druze (Figs 3 and and44).
The biogeographical affinities of the Druze are unique compared with neighbouring Levantine populations. Only a minute fraction of Lebanese and Syrians share a Turkish affinity (Fig. 3), and both Syrians and Palestinians are highly localised to the Levant. While these results do not rule out a partial Turkish ancestry for some of the Syrians, they suggest that any genetic evidence for such an ancestry has decayed over time due to on-going gene exchange with Levantine populations and the absence of large inflows of migrants with relatively distinct population structure. The biogeographical affinity of Palestinians concurs with previous studies employing uniparental markers33 and historical records, which suggest that they descended, at least in part, from local Israelite inhabitants who converted to Islam following the Muslim conquest in the early 7th century6,34.
Fascinatingly, most Lebanese individuals were predicted along the northwestern Incense Route leading from southern Arabia to the Mediterranean, used by merchants between the 4th century B.C. and the 2nd century A.D. This multi-origin of the Lebanese (Fig. 3[C1]) may be explained either by the 7th century Arabian expansion, which saw a large scale movement of Arabian tribes from the Arabian Peninsula into the Middle East, or by the northern expansion of nomadic Bedouin tribes known as the Nabataeans. By the end of the fourth century the Nabataeans had established an empire which occupied Northern Arabia and the Southern Levant for four hundred years, making migration into Lebanon at this time highly probable35. However, as both Nabatean and late Arab conquerors inhabited the same geographical regions and emerged around similar historical periods, they likely share the same genetic background. Therefore, the exact ancestry of Lebanese cannot be properly deciphered without ancient DNA from the potential ancestral populations, currently unavailable.
This critical aspect of Druze life has been neglected by many previous studies on the origin of Druze. Our GPS analyses localised most Druze to the highest and largest mountainous Regions of southeast Turkey and northern Iraq and the remaining individuals close to the Syrian Mount Hauran, where most Druze reside today. Our analyses also indicated an on-going mixture between these two groups. These findings hint at a tantalizing possibility that, over time, at least some of the proto-Druze may have developed a genetic adaptation to high altitudes, such as has been reported in several other mountainous populations36. Our findings are in agreement with the results obtained by fineSTRUCTURE where populations were clustered into clades based on their population structure similarity27. Druze were clustered into the “West Asian” clade together with Adygei, Armenian, Cypriot, Georgian, Iranian, Lezgin and Turkish populations. Such findings are also in agreement with a recent ancient DNA study28, where Druze exhibited genetic similarity to Chalcolithic and Bronze Age Armenians and a Chalcolithic Anatolian. In that study, Druze clustered remotely from all Bronze Age and Neolithic Levantines, whereas Palestinians, Bedouins, Syrians and a few Lebanese clustered with Levantine populations.
A conclusion of genetic isolation can therefore be reached only after extensive genetic comparisons of the putative isolated population with its neighbouring populations and potential progenitors and after excluding artefacts that may lead to such an impression, like small sample sizes, studying insufficient numbers of markers and questionable study designs.
Zidan et al.15 have studied Israeli Druze that trace all four grandparents to the same communities in Syria and Lebanon. The authors argued that the Druze are a ‘population isolate’ based on two analyses. First, a PC analysis portrayed Druze as clustered separately from “any other population” enveloped by genetic nothingness and immersed in a genetic vacuum. This statement is peculiar since not only were several populations for which genetic data were available not tested, but some of the populations included in latter analyses were excluded from this analysis, critically Lebanese, who, like Eurasian Jews, have been repeatedly shown to cluster with the Druze in other PC analyses17,21,53,54. Second, an identical-by-descent (IBD) analysis yielded no shared segments between Druze and non-Druze. However, the IBD segments used for that analysis were 3 cM, 15 times higher than the recommended threshold55. Had the authors applied a more reasonable threshold of 1 cM, as shown in Fig. 6, they would have likely obtained a much higher IBD sharing between the Lebanese Druze and Lebanese non-Druze, as can be expected from the Lebanese origins of the Druze included in their cohort.
Throughout the mid- to late-19th century scientists used a range of problematic methods to argue that the Sami people were isolated from the Norwegian minority, often noting their purportedly distinct genetic ancestry. This assumption had many negative consequences for the Sami people, impacting on their territorial and political rights while contributing to the justification of wide-spread and systematic discrimination at the hands of governments. It is fundamental that any attempt at classifying a population, such as the Druze, as ‘genetic isolates’ is approached with caution and is founded on irrefutable genetic evidence as well as historical, sociological and administrative data.
Since the emergence of the Druze at the end of the first millennium A.D., travellers, historians and anthropologists have attempted to infer their population history without successfully reaching a consensus. The biogeographical analysis localised many of the Druze to the Zagros Mountains and the mountains surrounding Lake Van and postulated that their migration path ran along a trajectory from southeast Turkey to southeast Syria. The dating analysis points to a major admixture event, which may have occurred towards the end of the Middle Ages in support of a Seljuk ancestry for the proto-Druze. Considering the genetic relatedness of Druze to ancient Near Eastern populations, our findings suggest that the habitual preference of the Druze to high mountains, which has earned them the description “mountain dwellers”, has ancient roots. A genetic analysis of the Druze in conjunction with the accumulating evidence in literature (e.g. ref. 27) dispels unsupported allegations that the Druze represent a ‘genetic isolate’. While a religious Druze minority living in remote Levantine enclaves may practice endogamy that often results in genetic abnormalities, some of which may be due to de novo mutations that segregate in particular families or villages (e.g. refs 12, 22 and 60), they do not represent the majority of the population and cannot be considered a ‘population isolate’ by acceptable standards. Further large scale studies would be necessary to determine the nature of these mutations.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5111078/
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Originally Posted by Witness
Your baby pan-Turanist ranting won't get you anywhere, Kiro. The Druze originally came from South-Eastern Anatolia and etc, and it perfectly coincides with the genetic study. Your ranting is completely irrelevant to the truth on the matter.
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