In human genetics, Haplogroup U is a human mitochondrial DNA (mtDNA) haplogroup, a group of people who descend from a woman in the Haplogroup R (mtDNA) branch of the Genographic tree, who lived around 55,000 years ago. Her descendants gave birth to several different subgroups, some of which exhibit specific geographic homelands. The old age has led to a wide distribution of the descendant subgroups that harbor specific European, northern African, Indian, Arab, northern Caucasus Mountains and the Near East clades.^[1]

Subdivisions

Haplogroup U is subdivided into Haplogroups U1-U8. Haplogroup K is a subclade of U8^[2].

Haplogroup U1

Haplogroup U2

Haplogroup U3

Haplogroup U3 is defined by the HVR1 transition A16343G. It is found at low levels throughout Europe (about 1% of the population), the Near East (about 2.5% of the population), and Central Asia (1%). U3 is present at higher levels among populations in the Caucasus (about 6%) and among Lithuanian, Polish, and Spanish Romani populations (36-56%). ^{[3] [4] [5]}

Haplogroup U4

Haplogroup U4 has its origin in the Upper Palaeolithic, dating to approximately 25,000 years ago. It is widely distributed in Europe, and has been implicated in the expansion of modern humans into Europe occurring before the Last Glacial Maximum.

Haplogroup U5

The oldest mtDNA in Europe which is human (i.e. Homo Sapiens and not Neanderthal or other archaic individual) is U5 and U8a (see below). The age of U5 is estimated at 50,000 but could be as old as 60,500 years.

The presence of haplogroup U5 in Europe pre-dates the expansion of agriculture in Europe. Bryan Sykes' popular book The Seven Daughters of Eve says it shows up 45,000-50,000 years ago in Delphi, Greece and named the originator of haplogroup U5 Ursula. It shows that U5 is the first out of Africa into Europe, and that it shows up as the first Europeans in two places, Delphi and Spain around 50,000 years ago.

By another source haplogroup U5, age is estimated at about 52,000 kya, being the oldest subclade of haplogroup U.^[6]

Haplogroup U5 and its subclades U5a and U5b form the highest population concentrations in the far north, in Sami, Finns, and Estonians, but it is spread widely at lower levels throughout Europe. This distribution, and the age of the haplogroup, indicate individuals from this haplogroup were part the initial expansion tracking the retreat of ice sheets from Europe ~10kya.

Haplogroup U5 is found also in small frequencies and at much lower diversity in the Near East and parts of Africa, suggesting back-migration of people from northern Europe to the south.^[1]

U5 and U6 are "sister mtDNA groups" with a common ancestor (probably in West Asia).

• Mitochondrial DNA and human evolution: In search of Eve

• National Geographic's Genographic project

• The Real Eve: Modern Man's Journey Out of Africa, Stephen Oppenheimer, Carroll & Graf, New York, 2003.

• Brian Hamman's Clan Ursula (U5 sub-group) Website

• MtDNA Haplogroup U5 Webpage at WorldFamilies.net

Haplogroup U6

Haplogroup U6 is a group of people who descend from a woman in the Haplogroup R (mtDNA) branch of the Genographic tree. It is common (around 10% of the people) ^[1] in North Africa (with a maximum of 29% in Algerian Berbers^[7]) and the Canary Islands. It is also found in the Iberian peninsula, where it has the highest diversity (10 out of 19 sublineages are only found in this region and not in Africa)^[7], Eastern Africa and occasionally in other locations.

In spite of the highest diversity of Iberian U6, Maca-Meyer argues for an East African origin of this clade based on the highest diversity of subclade U6a in that region^[7], where it would have arrived from West Asia. She estimates the age of U6 between 25,000 and 66,000 years BP.

U6 has three main subclades^[7]:

• U6a: it is the most widespread (from Canary Islands and Iberian Peninsula to Syria, Ethiopia and Kenya) and has highest diversity in Eastern Africa. Estimated age: 24-27,500 BP. It has one major subclade:
  • U6a1: with similar distribution to U6a. Estimated age: 15-20,000 BP.
• U6b: shows a more patched and western distribution. In the Iberian peninsula U6b is more frequent in the North (while U6a is in the South). It has also been found in low amounts in Morocco, Algeria, Senegal and Nigeria. Estimated age: 8,500-24,500 BP. It has one subclade:
  • U6b1: found only in the Iberian peninsula and the Canary Islands. Estimated age: c. 6000 BP.
• U6c: only found in Morocco and Canary Islands. Estimated age: 6,000-17,500 BP.

U6a and U6b share a common basal mutation (16219) that is not present in U6c.

Haplogroup U7

Many European populations lack Haplogroup U7, but its frequency climbs over 4% in the Near East and up to 5% in Pakistan, reaching nearly 10% level in Iranians. In India, haplogroup U7 frequency peaks at over 12% in Gujarat, the westernmost state of India, while for the whole of India its frequency stays around 2%. Expansion times and haplotype diversities for the Indian and Near and Middle Eastern U7 mtDNAs are strikingly similar. The possible homeland of this haplogroup spans Indian Gujarat and Iran because from there its frequency declines steeply both to the east and to the west. If the origin were in Iran rather than in India, then its equally high frequency as well as diversity in Gujarat favors a scenario whereby U7 has been introduced to the coastal western India either very early, or by multiple founders. http://evolutsioon.ut.ee/publications/Metspalu2004.pdf#.

Haplogroup U8

Haplogroup U8a

The Basques have the most ancestral phylogeny in Europe for the mitochondrial haplogroup U8a, a rare subgroup of U8, placing the Basque origin of this lineage in the Upper Palaeolithic. The lack of U8a lineages in Africa suggests that their ancestors may have originated from West Asia^[2].

Haplogroup U8b

This clade has been found in Italy and Jordan^[2].

Haplogroup K

Haplogroup K makes up a sizeable fraction of European and West Asian mtDNA lineages. It is now known it is actually a subclade of haplogroup U8^[2].

See also

• Genealogical DNA test
• Human mitochondrial genetics

External links

• Spread of Haplogroup U, from National Geographic
• Ursula (U5)
• U6b
• Haplogroup U4 (Ulrike)
• The India Genealogical DNA Project
• Danish Demes Regional DNA Project: mtDNA Haplogroup U
• Most of the extant mtDNA boundaries in South and Southwest Asia were likely shaped during the initial settlement of Eurasia by anatomically modern humans, Mait Metspalu et al., 2004

Notes

1. ↑ ^{a b c} The Genographic Project at National Geographic
2. ↑ ^{a b c d} A. González et al. ''The mitochondrial lineage U8a reveals a Paleolithic settlement in the Basque country''. BMC Genomics, 2006
3. ↑ http://evolutsioon.ut.ee/publications/Richards2000.pdf
4. ↑ http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/383236
5. ↑ Blackwell Synergy - Cookie Absent
6. ↑ Barbujani G, Bertorelle G. "Genetics and the population history of Europe." Proceedings of the National Academy of Sciences, 2001.http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=11136246&dopt=AbstractPlus
7. ↑ ^{a b c d} N. Maca-Mayer, ''Mitochondrial DNA transit between West Asia and North Africa inferred from U6 phylogeography''. BMC Genetics, 2003