Haplogroup X (mtDNA)

Haplogroup X is a human mitochondrial DNA (mtDNA) haplogroup. It is found in North America, Europe, Western Asia, North Africa, and the Horn of Africa.

Haplogroup X diverged from haplogroup N roughly 30,000 years ago (just prior to or during the Last Glacial Maximum). It is in turn ancestral to subclades X2 and X1, which arose 16-21 thousand and 14-24 thousand years ago, respectively.

Distribution Haplogroup X is found in approximately 2% of native Europeans, and 13% of all native North Americans. Additionally, the Haplogroup is present in around 3% of Assyrians, with high concentrations in Erzurum, Turkey as well. Notably, the haplogroup is especially common, at 14.3%, among the natives of Bahariya Oasis (Western Desert, Egypt. The X1 subclade is much less frequent, and is largely restricted to North Africa, the Horn of Africa and the Near East.

Subclade X2 appears to have undergone extensive population expansion and dispersal around or soon after the Last Glacial Maximum, roughly 20,000 years ago. It is more strongly represented in the Near East, the Caucasus, and southern Europe, and somewhat less strongly present in the rest of Europe. The highest concentrations are found in the Ojibwe (25%), Sioux (15%), Nuu-Chah-Nulth (12%), Georgia (8%), Orkney (7%), and amongst the Druze in Israel (27%). Subclades of X2 are not present in South American Amerindian populations. whose 9000-year old remains were discovered in Washington State.

Archaeogenetics Haplogroup X has been found in various other bone specimens that were analysed for ancient DNA, including specimens associated with the Alföld Linear Pottery (X2b-T226C, Garadna-Elkerülő út site 2, 1/1 or 100%), Linearbandkeramik (X2d1, Halberstadt-Sonntagsfeld, 1/22 or ~5%), and Iberia Chalcolithic (X2b, La Chabola de la Hechicera, 1/3 or 33%; X2b, El Sotillo, 1/3 or 33%; X2b, El Mirador Cave, 1/12 or ~8%) cultures. Abel-beth-maachah 2201 was a man who lived between 1014 and 836 BC during the Levant Iron Age and was found in the region now known as Abel Beth Maacah, Metula, Israel. He was associated with the Galilean cultural group. His direct maternal line belonged to mtDNA haplogroup X2b. Haplogroup X has been found in ancient Assyria and ancient Egyptian mummies excavated at the Abusir el-Meleq archaeological site in Middle Egypt, which date from the late New Kingdom and Roman periods. Fossils excavated at the Late Neolithic site of Kelif el Boroud in Morocco, which have been dated to around 5,000 years old, have also been found to carry the X2 subclade.

Druze In Eurasia, the greatest frequency and variety of haplogroup X is observed in the Druze, a minority population in Israel, Jordan, Lebanon, and Syria, as much in X1 (16%) as in X2 (11%). The Druze also have much diversity of X lineages. This pattern of heterogeneous parental origins is consistent with Druze oral tradition. The Galilee Druze represent a population isolate, so their combination of a high frequency and diversity of X signifies a phylogenetic refugium, providing a sample snapshot of the genetic landscape of the Near East prior to the modern age.

North America

Haplogroup X is also one of the five haplogroups found in the indigenous peoples of the Americas. (namely, X2a subclade).

Although it occurs only at a frequency of about 3% for the total current indigenous population of the Americas, it is a bigger haplogroup in northern North America, where among the Algonquian peoples it comprises up to 25% of mtDNA types. It is also present in lesser percentages to the west and south of this area—among the Sioux (15%), the Nuu-chah-nulth (11%–13%), the Navajo (7%), and the Yakama (5%). In Latin America, Haplotype X6 was present in the Tarahumara 1.8% (1/53) and Huichol 20% (3/15) X6 and X7 was also found in 12% in Yanomani people.

Unlike the four main Native American mtDNA haplogroups (A, B, C, D), X is not strongly associated with East Asia. The main occurrence of X in Asia discovered so far is in the Altai people in Siberia.

One theory of how the X Haplogroup ended up in North America is that the people carrying it migrated from central Asia along with haplogroups A, B, C, and D, from an ancestor from the Altai Region of Central Asia. Two sequences of haplogroup X2 were sampled further east of Altai among the Evenks of Central Siberia. These two sequences belong to X2* and X2b. It is uncertain if they represent a remnant of the migration of X2 through Siberia or a more recent input.

This relative absence of haplogroup X2 in Asia was one of the major factors used to support the Solutrean hypothesis during the early 2000s. The Solutrean hypothesis postulates that haplogroup X reached North America with a wave of European migration emerging from the Solutrean culture, a stone-age culture in south-western France and in Spain, by boat around the southern edge of the Arctic ice pack roughly 20,000 years ago.Carey, Bjorn (19 February 2006)."First Americans may have been European.Life Science. Retrieved on 10 August 2007. Since the later 2000s and during the 2010s, evidence has turned against the Solutrean hypothesis, as no presence of mt-DNA ancestral to X2a has been found in Europe or the Near East. The New World X2a lineage is not derived from the Old World lineages such as X2b, X2c, X2d, X2e, and X2f, indicating an early origin of the New World lineage "likely at the very beginning of their expansion and spread from the Near East". A 2008 study came to the conclusion that the presence of haplogroup X in the Americas does not support migration from Solutrean-period Europe. The lineage of haplogroup X in the Americas is not derived from a European subclade, but rather represent an independent subclade, labelled X2a."The similarities in ages and geographical distributions for C4c and the previously analyzed X2a lineage provide support to the scenario of a dual origin for Paleo-Indians. Taking into account that C4c is deeply rooted in the Asian portion of the mtDNA phylogeny and is indubitably of Asian origin, the finding that C4c and X2a are characterized by parallel genetic histories definitively dismisses the controversial hypothesis of an Atlantic glacial entry route into North America. The X2a subclade has not been found in Eurasia, and has most likely arisen within the early Paleo-Indian population, at roughly 13,000 years ago.X2a is dated in Soares et al. (2009). A basal variant of X2a was found in the Kennewick Man fossil (ca. 9,000 years ago)."X2a has not been found anywhere in Eurasia, and phylogeography gives us no compelling reason to think it is more likely to come from Europe than from Siberia. Furthermore, analysis of the complete genome of Kennewick Man, who belongs to the most basal lineage of X2a yet identified, gives no indication of recent European ancestry and moves the location of the deepest branch of X2a to the West Coast, consistent with X2a belonging to the same ancestral population as the other founder mitochondrial haplogroups. Nor have any high-resolution studies of genome-wide data from Native American populations yielded any evidence of Pleistocene European ancestry or trans-Atlantic gene flow."

Subclades Tree This phylogenetic tree of haplogroup X subclades is based on the paper by Mannis van Oven and Manfred Kayser Updated comprehensive phylogenetic tree of global human mitochondrial DNA variation and subsequent published research. X X1'2'3 X1'3 X1 X1a X1a1 X1b X1c X3 X3a X2 X2-G225A X2a'j X2a X2a1 X2a1a X2a1a1 X2a1b X2a1b1 X2a1b1a X2a1c X2a2 X2j X2b'd X2b X2b-T226C X2b1 X2b2 X2b3 X2b4 X2b4a X2b4a1 X2b5 X2b6 X2b6a X2b7 X2b8 X2b9 X2b10 X2b10a X2b11 X2b-T226C-C16192T X2b12 X2b13 X2d X2d1 X2d1a X2d2 X2c X2c1 X2c1a X2c1b X2c1c X2c1c1 X2c1d X2c1e X2c2 X2e X2e1 X2e1a X2e1a1 X2e1a1a X2e1b X2e2 X2e2a X2e2a1 X2e2a2 X2e2b X2e2b1 X2e2c X2e2c1 X2-G225A-G153A! X2g X2l X2-G225A-T16223C X2h X2i X2i-A225G! X2i1 X2m'n X2m X2m1 X2m2 X2n X2o X2o1 X2f X2f1 X2g X2h X2k X2p X2p1 X4

Notable members Abraham Lincoln carries haplogroup X1. Steven J. Heine carries haplogroup X2c1.

Haplogroup X (mtDNA)

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