Haplogroup X (mtDNA)
Encyclopedia
In human mitochondrial genetics
, Haplogroup X is a human mitochondrial DNA (mtDNA) haplogroup. It has a widespread global distribution but no major regions of distinct localization.
The genetic sequences of haplogroup X diverged originally from haplogroup N
, and subsequently further diverged about 30,000 years ago to give two sub-groups, X1 and X2.
, the Near East
, and North Africa
.
Sub-group X1 is much less numerous, and restricted to North and East Africa
, and also the Near East.
Sub-group X2 appears to have undergone extensive population expansion and dispersal around or soon after the last glacial maximum
, about 21,000 years ago. It is more strongly present in the Near East, the Caucasus, and Mediterranean Europe
; and somewhat less strongly present in the rest of Europe. Particular concentrations appear in Georgia
(8%), the Orkney Islands
(in Scotland
), (7%) and amongst the Israeli Druze
community (27%). Subclades X2a and X2g are found in North America
, but are not present in native Latin Americans.
, 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.
.
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%).
Unlike the four main Native American mtDNA haplogroups (A
, B
, C
, D
), and the Y-chromosome sub-haplogroup Q1a3a, X is not at all strongly associated with East Asia
. The main occurrence of X in Asia discovered so far is in the Altay people
in Southwestern Siberia
, and detailed examination has shown that the Altaian sequences are all almost identical (haplogroup X2e), suggesting that they arrived in the area probably from the South Caucasus
more recently than 5,000 BP
.
However other research shows that Altaians have maintained their native identity and only begun, very recently, to mix with groups (mostly Russians and Kazakhs) who do not show mtDNA haplogroup X. Genetic studies and researchers show, "the analysis of the tribal structure of Southern Altaians has shown that the present-day Altaians have retained their native language and ethnic identity. They have begun to mix with other ethnic groups (mostly Russians and Kazakhs) only recently, so the interethnic admixture is estimated to be <5% (Luzina 1987; Osipova et al. 1997). The haplogroup X mtDNAs have not been found in populations of central Asia, including Kazakhs, Uighurs, and Kirghizs (Comas et al. 1998). Since the frequency of haplogroup X in Russians is extremely low (3 of 336; Orekhov et al. 1999; Malyarchuk and Derenko 2000; authors’ unpublished data), the recent European admixture cannot explain the presence of haplogroup X in the Altaians. Hence, the results of the present study allow us to suggest that haplogroup X was the part of the ancestral gene pool for Altaian populations, being found both in northern and southern Altaians."
In addition these same researchers have detailed that the mtDNA haplogroup X haplotype present in the Altaians of Siberia is intermediate between Native Americans clades and that of Europeans. As a Russian research group observed, "American Indian and European haplogroup X mtDNAs ... are distantly related to each other". They propose however not an early European colonization of America, but that Altaians contributed to migrants bound for Europe and America; "The network further suggests that the Altaian X haplotypes occupy the intermediate position between European and American Indian haplogroup X mtDNA lineages"
One theory of how the X Haplogroup ended up in North America is it migrated from central Asia along with the A, B, C, and D Haplogroups, 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 is one of the major factors causing the current rethinking of the peopling of the Americas
. However, the New World
haplogroup X2a is as different from any of the Old World
X2b, X2c, X2d, X2e, and X2f lineages as they are from each other, indicating an early origin "likely at the very beginning of their expansion and spread from the Near East".
The Solutrean Hypothesis
postulates that haplogroup X reached North America with a wave of European migration about 20,000 BP by the Solutrean
s, a stone-age culture in south-western France
and in Spain
, by boat around the southern edge of the Arctic ice pack.
Various articles by a group of researchers in Brazil (except for David Glenn Smith, of U.C. Davis) argue against the Solutrean hypothesis. In one 2008 article, in the American Journal of Human Genetics, they assert: "Our results strongly support the hypothesis that haplogroup X, together with the other four main mtDNA haplogroups, was part of the gene pool of a single Native American founding population; therefore they do not support models that propose haplogroup-independent migrations, such as the migration from Europe posed by the Solutrean hypothesis."
Again in 2008 that same team of genetic scientists republished essentially the same article under the same title, making a similar point: "Here we show, by using 86 complete mitochondrial genomes, that all Native American haplogroups, including haplogroup X, were part of a single founding population, thereby refuting multiple-migration models."
, Bryan Sykes
named the originator of this mtDNA haplogroup "Xenia".
Human mitochondrial genetics
Human mitochondrial genetics is the study of the genetics of the DNA contained in human mitochondria. Mitochondria are small structures in cells that generate energy for the cell to use, and are hence referred to as the "powerhouses" of the cell....
, Haplogroup X is a human mitochondrial DNA (mtDNA) haplogroup. It has a widespread global distribution but no major regions of distinct localization.
Origin
Haplogroup N (mtDNA)
In human mitochondrial genetics, Haplogroup N is a human mitochondrial DNA haplogroup. An enormous haplogroup spanning many continents, the macro-haplogroup N, like its sibling M, is a descendant of haplogroup L3....
, and subsequently further diverged about 30,000 years ago to give two sub-groups, X1 and X2.
Distribution
Overall haplogroup X accounts for about 2% of the population of EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, the Near East
Near East
The Near East is a geographical term that covers different countries for geographers, archeologists, and historians, on the one hand, and for political scientists, economists, and journalists, on the other...
, and North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...
.
Sub-group X1 is much less numerous, and restricted to North and East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
, and also the Near East.
Sub-group X2 appears to have undergone extensive population expansion and dispersal around or soon after the last glacial maximum
Last Glacial Maximum
The Last Glacial Maximum refers to a period in the Earth's climate history when ice sheets were at their maximum extension, between 26,500 and 19,000–20,000 years ago, marking the peak of the last glacial period. During this time, vast ice sheets covered much of North America, northern Europe and...
, about 21,000 years ago. It is more strongly present in the Near East, the Caucasus, and Mediterranean Europe
Southern Europe
The term Southern Europe, at its most general definition, is used to mean "all countries in the south of Europe". However, the concept, at different times, has had different meanings, providing additional political, linguistic and cultural context to the definition in addition to the typical...
; and somewhat less strongly present in the rest of Europe. Particular concentrations appear in Georgia
Georgia (country)
Georgia is a sovereign state in the Caucasus region of Eurasia. Located at the crossroads of Western Asia and Eastern Europe, it is bounded to the west by the Black Sea, to the north by Russia, to the southwest by Turkey, to the south by Armenia, and to the southeast by Azerbaijan. The capital of...
(8%), the Orkney Islands
Orkney Islands
Orkney also known as the Orkney Islands , is an archipelago in northern Scotland, situated north of the coast of Caithness...
(in Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
), (7%) and amongst the Israeli Druze
Druze
The Druze are an esoteric, monotheistic religious community, found primarily in Syria, Lebanon, Israel, and Jordan, which emerged during the 11th century from Ismailism. The Druze have an eclectic set of beliefs that incorporate several elements from Abrahamic religions, Gnosticism, Neoplatonism...
community (27%). Subclades X2a and X2g are found in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, but are not present in native Latin Americans.
Druze
The greatest frequency of haplogroup X is observed in the DruzeDruze
The Druze are an esoteric, monotheistic religious community, found primarily in Syria, Lebanon, Israel, and Jordan, which emerged during the 11th century from Ismailism. The Druze have an eclectic set of beliefs that incorporate several elements from Abrahamic religions, Gnosticism, Neoplatonism...
, a minority population in Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
, Jordan
Jordan
Jordan , officially the Hashemite Kingdom of Jordan , Al-Mamlaka al-Urduniyya al-Hashemiyya) is a kingdom on the East Bank of the River Jordan. The country borders Saudi Arabia to the east and south-east, Iraq to the north-east, Syria to the north and the West Bank and Israel to the west, sharing...
, Lebanon
Lebanon
Lebanon , officially the Republic of LebanonRepublic of Lebanon is the most common term used by Lebanese government agencies. The term Lebanese Republic, a literal translation of the official Arabic and French names that is not used in today's world. Arabic is the most common language spoken among...
, and Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
, 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
Galilee
Galilee , is a large region in northern Israel which overlaps with much of the administrative North District of the country. Traditionally divided into Upper Galilee , Lower Galilee , and Western Galilee , extending from Dan to the north, at the base of Mount Hermon, along Mount Lebanon to the...
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 AmericasIndigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
.
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
Algonquian peoples
The Algonquian are one of the most populous and widespread North American native language groups, with tribes originally numbering in the hundreds. Today hundreds of thousands of individuals identify with various 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
Sioux
The Sioux are Native American and First Nations people in North America. The term can refer to any ethnic group within the Great Sioux Nation or any of the nation's many language dialects...
(15%), the Nuu-Chah-Nulth
Nuu-chah-nulth
The Nuu-chah-nulth are one of the Indigenous peoples of the Pacific Northwest Coast of Canada...
(11%–13%), the Navajo
Navajo people
The Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...
(7%), and the Yakama
Yakama
The Confederated Tribes and Bands of the Yakama Nation, or simply Yakama Nation , is a Native American group with nearly 10,000 enrolled members, living in Washington. Their reservation, along the Yakima River, covers an area of approximately 1.2 million acres...
(5%).
Unlike the four main Native American mtDNA haplogroups (A
Haplogroup A (mtDNA)
In human mitochondrial genetics, Haplogroup A is a human mitochondrial DNA haplogroup.-Origin:Haplogroup A is believed to have arisen in Asia some 30,000-50,000 years before present...
, B
Haplogroup B (mtDNA)
In human mitochondrial genetics, Haplogroup B is a human mitochondrial DNA haplogroup.-Origin:Haplogroup B is believed to have arisen in Asia some 50,000 years before present. Its ancestral haplogroup was Haplogroup R....
, C
Haplogroup C (mtDNA)
In human mitochondrial genetics, Haplogroup C is a human mitochondrial DNA haplogroup.-Origin:Haplogroup C is believed to have arisen somewhere between the Caspian Sea and Lake Baikal some 60,000 years before present. It is a descendant of the haplogroup M.-Distribution:Haplogroup C is found in...
, D
Haplogroup D (mtDNA)
In human mitochondrial genetics, Haplogroup D is a human mitochondrial DNA haplogroup.-Origin:Haplogroup D is believed to have arisen in Asia some 48,000 years before present. It is a descendant haplogroup of haplogroup M.-Distribution:...
), and the Y-chromosome sub-haplogroup Q1a3a, X is not at all strongly associated with East Asia
East Asia
East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...
. The main occurrence of X in Asia discovered so far is in the Altay people
Altay people
The Altay or Altai are an ethnic group of Turkic people living in the Siberian Altai Republic and Altai Krai and surrounding areas of Tuva and Mongolia. For alternative ethnonyms see also Teleut, Tele, Telengit, Mountain Kalmuck, White Kalmuck, Black Tatar, Oirat/Oirot.The Uriankhai people were...
in Southwestern Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, and detailed examination has shown that the Altaian sequences are all almost identical (haplogroup X2e), suggesting that they arrived in the area probably from the South Caucasus
South Caucasus
The South Caucasus is a geopolitical region located on the border of Eastern Europe and Southwest Asia also referred to as Transcaucasia, or The Trans-Caucasus...
more recently than 5,000 BP
5th millennium
The fifth millennium is a period of time that will begin on January 1, 4001, and will end on December 31, 5000.-Astronomical events:* 4285 : Venus occults Regulus.* 4296 : Venus occults Antares....
.
However other research shows that Altaians have maintained their native identity and only begun, very recently, to mix with groups (mostly Russians and Kazakhs) who do not show mtDNA haplogroup X. Genetic studies and researchers show, "the analysis of the tribal structure of Southern Altaians has shown that the present-day Altaians have retained their native language and ethnic identity. They have begun to mix with other ethnic groups (mostly Russians and Kazakhs) only recently, so the interethnic admixture is estimated to be <5% (Luzina 1987; Osipova et al. 1997). The haplogroup X mtDNAs have not been found in populations of central Asia, including Kazakhs, Uighurs, and Kirghizs (Comas et al. 1998). Since the frequency of haplogroup X in Russians is extremely low (3 of 336; Orekhov et al. 1999; Malyarchuk and Derenko 2000; authors’ unpublished data), the recent European admixture cannot explain the presence of haplogroup X in the Altaians. Hence, the results of the present study allow us to suggest that haplogroup X was the part of the ancestral gene pool for Altaian populations, being found both in northern and southern Altaians."
In addition these same researchers have detailed that the mtDNA haplogroup X haplotype present in the Altaians of Siberia is intermediate between Native Americans clades and that of Europeans. As a Russian research group observed, "American Indian and European haplogroup X mtDNAs ... are distantly related to each other". They propose however not an early European colonization of America, but that Altaians contributed to migrants bound for Europe and America; "The network further suggests that the Altaian X haplotypes occupy the intermediate position between European and American Indian haplogroup X mtDNA lineages"
One theory of how the X Haplogroup ended up in North America is it migrated from central Asia along with the A, B, C, and D Haplogroups, from an ancestor from the Altai Region of Central Asia. Two sequences of haplogroup X2 were sampled further east of Altai among the Evenks
Evenks
The Evenks are a Tungusic people of Northern Asia. In Russia, the Evenks are recognized as one of the Indigenous peoples of the Russian North, with a population of 35,527...
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 is one of the major factors causing the current rethinking of the peopling of the Americas
Models of migration to the New World
There have been several models for the human settlement of the Americas proposed by various academic communities. The question of how, when and why humans first entered the Americas is of intense interest to archaeologists and anthropologists, and has been a subject of heated debate for centuries...
. However, the New World
New World
The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...
haplogroup X2a is as different from any of the Old World
Old World
The Old World consists of those parts of the world known to classical antiquity and the European Middle Ages. It is used in the context of, and contrast with, the "New World" ....
X2b, X2c, X2d, X2e, and X2f lineages as they are from each other, indicating an early origin "likely at the very beginning of their expansion and spread from the Near East".
The Solutrean Hypothesis
Solutrean hypothesis
The Solutrean hypothesis proposes that peoples from Europe may have been among the earliest settlers in the Americas, as evidenced by similarities in stone tool technology of the Solutrean culture from prehistoric Europe to that of the later Clovis tool-making culture found in the Americas. It was...
postulates that haplogroup X reached North America with a wave of European migration about 20,000 BP by the Solutrean
Solutrean
The Solutrean industry is a relatively advanced flint tool-making style of the Upper Palaeolithic, from around 22,000 to 17,000 BP.-Details:...
s, a stone-age culture in south-western France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
and in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
, by boat around the southern edge of the Arctic ice pack.
Various articles by a group of researchers in Brazil (except for David Glenn Smith, of U.C. Davis) argue against the Solutrean hypothesis. In one 2008 article, in the American Journal of Human Genetics, they assert: "Our results strongly support the hypothesis that haplogroup X, together with the other four main mtDNA haplogroups, was part of the gene pool of a single Native American founding population; therefore they do not support models that propose haplogroup-independent migrations, such as the migration from Europe posed by the Solutrean hypothesis."
Again in 2008 that same team of genetic scientists republished essentially the same article under the same title, making a similar point: "Here we show, by using 86 complete mitochondrial genomes, that all Native American haplogroups, including haplogroup X, were part of a single founding population, thereby refuting multiple-migration models."
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
- X1a
- X1a1
- X1b
- X1a
- X2
- X2a
- X2a1
- X2a1a
- X2a1b
- X2a2
- X2a1
- X2b
- X2b1
- X2b2
- X2b3
- X2b4
- X2c
- X2c1
- X2d
- X2e
- X2e1
- X2e1a
- X2e1a1
- X2e1a1a
- X2e1a1
- X2e1a
- X2e2
- X2e1
- X2f
- X2g
- X2h
- X2a
- X1
Popular culture
In his popular book The Seven Daughters of EveThe Seven Daughters of Eve
The Seven Daughters of Eve is a book by Bryan Sykes that presents the theory of human mitochondrial genetics to a general audience...
, Bryan Sykes
Bryan Sykes
Bryan Sykes is a former Professor of Human Genetics at the University of Oxford and a current Fellow of Wolfson College.Sykes published the first report on retrieving DNA from ancient bone...
named the originator of this mtDNA haplogroup "Xenia".
See also
- Genealogical DNA testGenealogical DNA testA genealogical DNA test examines the nucleotides at specific locations on a person's DNA for genetic genealogy purposes. The test results are not meant to have any informative medical value and do not determine specific genetic diseases or disorders ; they are intended only to give genealogical...
- Genetic GenealogyGenetic genealogyGenetic genealogy is the application of genetics to traditional genealogy. Genetic genealogy involves the use of genealogical DNA testing to determine the level of genetic relationship between individuals.-History:...
- Human mitochondrial geneticsHuman mitochondrial geneticsHuman mitochondrial genetics is the study of the genetics of the DNA contained in human mitochondria. Mitochondria are small structures in cells that generate energy for the cell to use, and are hence referred to as the "powerhouses" of the cell....
- Population GeneticsPopulation geneticsPopulation genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes into account the factors of recombination, population subdivision and population...
- Human mitochondrial DNA haplogroupsHuman mitochondrial DNA haplogroupsIn human genetics, a human mitochondrial DNA haplogroup is a haplogroup defined by differences in human mitochondrial DNA. Haplogroups are used to represent the major branch points on the mitochondrial phylogenetic tree...
- Indigenous American genetic studies
External links
- General
- Mannis van Oven's – mtDNA subtree N
- Haplogroup X
- The Presence of Mitochondrial Haplogroup X in Altaians from South Siberia Miroslava V. Derenko, Tomasz Grzybowski, and others
- Ian Logan's DNA Site
- Carolyn Benson's X mtDNA Project at Family Tree DNAFamilyTreeDNAFamily Tree DNA is a commercial genetic genealogy company based in Houston, Texas with its partner laboratory, Arizona Research Labs, housed at the University of Arizona. Family Tree DNA offers analysis of autosomal DNA, YDNA, and mtDNA to individuals for genealogical purposes based on DNA samples...
- Spread of Haplogroup X, from National Geographic