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In human genetics, Haplogroup M is a human mitochondrial DNA (mtDNA) haplogroup. An enormous haplogroup spanning all the continents, the macro-haplogroup M, like its sibling N, is a descendant of the East African haplogroup L3

All mtDNA haplogroups found outside of Africa are descendants of either haplogroup M or its sibling haplogroup N. M and N are the signature haplogroups that define the out of Africa migration and the subsequent colonization of the rest of the world. The global distribution of haplogroups M and N, indicates that very likely, there was one particularly major prehistoric migration of humans out of Africa, and both M and N were part of the same colonization process.

Origins

There is widespread agreement in the scientific community both concerning the African ancestry of haplogroup L3 (haplogroup M's parent clade), and also that the Indian sub-continent played a pivotal role in the prehistory and dispersal of haplogroup M. However, whether or not the mutations which define haplogroup M itself first occurred within Asia or Africa has been a subject for ongoing discussion and study.

Much of this discussion has focused upon haplogroup M1, which is the only variant of macrohaplogroup M that is found in Africa. There are currently three possible scenarios that could explain the presence of M1 in Africa:

1. M1 evolved through an independent mutation.
2. M was present in the ancient population which later gave rise to M1 in Africa.
3. The presence of M1 in Africa is the result of a back-migration from Asia.

Regarding the Controversy, Gonzalez et al state:

Based on mitochondrial phylogeography it was proposed that M lineages expanded with the coastal route to southern Asia and Oceania and N lineages by the continental route to Eurasia . However, the posterior detection of primitive N lineages in southern areas as India and Australia weakened that hypothesis . As, in addition, the founder ages of M and N are very similar, the alternative hypothesis, that M and N founders derived from a single African migration, was favored by several authors . Another related disjunctive yet not settled is whether M and N (and its main branch R) arose inside or outside Africa.

Asian origin hypothesis

The hypothesis of Asia as the place of origin of macrohaplogroup M is supported by recent studies from Rajkumar et al. (2005), Olivieri et al. (2006) and Gonzalez et al. (2007), which contain new data that substantially contributes to the present understanding of the haplogroup. However an investigation into the Rajkumar et al study by Sun et al found numerous discrepancies, including the addition of phantom mutations. The study reported:

Rajkumar et al. (2005)Go provided 23 Indian M sequences that were deemed to be complete. On the basis of their phylogenetic tree, the authors negated the haplogroup status of M3 and M4. However, a site-by-site audit of their sequences revealed that the obtained data are problematic, with numerous basal mutations evidently missed as well as some phantom mutations inflicted.

The evidence in support of this view can be summarized as follows:

1. The highest frequencies worldwide of macrohaplogroup M are observed in Asia, specifically in India and Bangladesh, where frequencies range from 60%-80%.
2. The oldest sub-clades of macrohaplogroup M are found in India.
3. Every sub-clade of haplogroup M as well as all of its descendant branches (including those of M's Eurasian sister clade, haplogroup N) are found in Asia. (with some discussion possible only about sub-clade M1, concerning which see below).
4. Since macrohaplogroup M is geographically restricted in Africa whereas it is prevalent throughout Asia, the only way it could conceivably have originated in Africa is if it had orginated at an ancient time, since it had to spread throughout Asia and the New World where its descendant lineages are presently found. However, it is paradoxical that haplogroup M other populations within Africa besides North Africans and Horn Africans.
5. M1 is the only sub-clade of haplogroup M that has been observed in Africa, and:

• According to one recent study, M1 is a relatively recent lineage with a younger coalescence age than the Asian-exclusive M lineages. This means that there are no very old clades of M represented in Africa.
• The geographic distribution of M1 in Africa is predominantly North African/supra-equatorial and is largely confined to Afro-Asiatic speakers, which is inconsistent with the Sub-Saharan distribution of sub-clades of haplogroups L3 and L2 that have similar time depths.
• Contrary to the African origin hypothesis, the most ancestral M1 lineages have been found in Northwest Africa and in the Near East rather than East Africa.
• M1 is not restricted to Africa. Outside of Africa it is found in the Mediterranean, peaking in Iberia. M1 also has a presence in the Middle East, from the of the Arabian Peninsula with frequencies of 3.5%, to Anatolia and Iran with frequencies 5%. In addition, M1 haplotypes have occasionally been observed in the Caucasus and the Trans Caucasus, and without any accompanying L lineages. M1 has also been detected in Central Asia, seemingly reaching as far as Tibet.
• The fact that the M1 sub-clade of macrohaplogroup M has a coalescence age which overlaps with that of haplogroup U6 (a Eurasian haplogroup whose presence in Africa is due to a back-migration from West Asia) and the distribution of U6 in Africa is also restricted to the same North African and Horn African populations as M1 supports the scenario that M1 and U6 were part of the same population expansion from Asia to Africa. However in a recent study by Olivieri et al, Haplogroup U6 was absent in Egyptian Berbers whereas M1 was found alongside other East African haplogroups.
• The timing of the proposed migration of M1 and U6-carrying peoples from West Asia to Africa (between 40,000 to 45,000 ybp) is also supported by the fact that it coincides with changes in climatic conditions that reduced the desert areas of North Africa, thereby rendering the region more accessible to entry from the Levant. This climatic change also temporally overlaps with the peopling of Europe by populations bearing haplogroup U5, the European sister clade of haplogroup U6.

African origin hypothesis

This was the dominant view around the year 2000, and has been argued as recently as 2004. It is supported by the following arguments and evidence.

1. L3, the parent clade of haplogroup M, is rare outside of Africa. According to Toomas Kivisild (2004), "the lack of L3 lineages other than M and N in India and among non-African mitochondria in general suggests that the earliest migration(s) of modern humans already carried these two mtDNA ancestors, via a departure route over the Horn of Africa."
2. Specifically concerning at least M1:

• Haplogroup M1 is largely restricted to Africa where the highest frequencies of M1 can be found in East Africa, particularly in Ethiopia. M1,is found in Europe and the Near East but at considerably lower frequencies than in Africa. Macrohaplogroup M has peak frequencies in India, but is rare in the Near East and Europe.
• Early studies once reported the age of haplogroup M1 to be similar to that of haplogroup M. Quintana et al. (1999) suggested that the age of the then-East African specific haplogroup M1, calculated using RFLP data (48,000±15,000), was compatible with that of the Indian-specific haplogroup M lineages (56,000±7,000).
• Sun et al. (2005) argue that the similarities between haplogroup M1 and the Indian-specific sub-clades of macrohaplogroup M are the result of random parallel mutations based on the lack of the variations that characterize M1 that they observed in their reconstructed ancestral motifs of all Indian M haplogroups.

Dispersal

A number of scholars had proposed that haplogroup M dispersed from Africa through the southern route across the Horn of Africa along the coastal regions of Asia onwards to New Guinea and Australia. These studies suggested that the migrations of haplogroups M and N occurred separately with haplogroup N heading northwards from East Africa to the Levant. However, numerous the results of numerous recent studies indicate that there was only one migration out of Africa and that haplogroups M and N were part of the same migration. This is based on the analysis of a number of relict populations along the proposed beachcombing route from Africa to Australia, all of which possessed both haplogroups N and M.

Distribution

M is the single most common mtDNA haplogroup in Asia, and peaks in Bangladesh where it represents two thirds of the maternal lineages, and is ubiquitous in India where it has a 60% frequency.

Due to its great age, haplogroup M is an mtDNA lineage which does not correspond well to present-day ethnic groups, as it spans Siberian, Native American, East Asian, Southeast Asian, Central Asian, South Asian, Melanesian as well as Egyptian, Ethiopian, Somali, European, and various Middle Eastern populations in lesser frequency.

Descendants of haplogroup M

Among the descendants of M are C, D, E, G, Q, and Z, with Z and G being observed in North Eurasian populations, C and D being shared between North Eurasian and Native American populations, E being observed in Southeast Asian populations, and Q being observed in Melanesian populations. The lineages M2, M3, M4, M5, M6, M18 and M25 are exclusive to South Asia, with M2 reported to be the oldest lineage on the Indian sub-continent. M7 and M8 are widespread Eastern Eurasian lineages.

List of Descendents

• Haplogroup M1 - found in North Africa, Horn of Africa, Mediterranean, and Middle East
  • Haplogroup M1c - oldest M1 sub-clade
  • Haplogroup M1a
• Haplogroup M2 - found in South Asia, with highest concentrations in SE India and Bangladesh; oldest haplogroup M lineage on the Indian sub-continent.
  • M2a - most common in Bangladesh
  • M2b - most common in SE India
• Haplogroup M3 - found mainly in South Asia, with highest concentrations in west and NW India
  • M3a - similar distribution
• Haplogroup M4 - found mainly in South Asia but some sequences in Eastern Saudi Arabia
  • Haplogroup M4a - found in Gujarat, India
  • Haplogroup M37a - found in Gujarat, India
• Haplogroup M5 - found in South Asia
  • Haplogroup M5a - found in Orissa, India
• Haplogroup M6 - found mainly in South Asia, with highest concentrations in mid-eastern India and Kashmir
  • Haplogroup M6b - found in Kerala, India
• Haplogroup M7 - found in East Asia, especially in Japan
• Haplogroup CZ/M8:
  • Haplogroup M8 - found in East Asia, especially in Japan
  • Haplogroup CZ
    • Haplogroup C - found especially in Northeast Asia
      • Haplogroup C1 - found in Asia and America (Native Americans and Hispanics in particular)
      • Haplogroup C4
    • Haplogroup Z - found among diverse Eurasian populations: Hazara, Finns, Japanese, Sami and some Russians.
• Haplogroup M9 - found in East and Southeast Asia
  • Haplogroup E (mtDNA) - a subclade of M9 - found especially in SE Asia
• Haplogroup M10 - small clade found in East Asia
• Haplogroup M11-12:
  • Haplogroup M11 - small clade found especially among the Chinese
  • Haplogroup M12 - small clade found in Japan
• Haplogroup M21 - small clade found in SE Asia
• Haplogroup M27-29:
  • Haplogroup M27 - found in Melanesia
  • Haplogroup M28 - found in Melanesia
  • Haplogroup M29 - found in Melanesia
• Haplogroup M31 - found in Andaman Islands
  • Haplogroup M31a1 - found among the Onge, in the Andaman Islands
• Haplogroup M32 - found in Andaman Islands
• Haplogroup M33 - small clade found in South Asia and Belarus
  • Haplogroup M33a - found in Gujarat, India
• Haplogroup M34 - small clade found in South Asia
  • Haplogroup M34a - found in Karnataka, India
• Haplogroup M35 - small clade found in South Asia and Slovakia
• Haplogroup M39 - found in South Asia
• Haplogroup M40 - found in South Asia
• Haplogroup M41 - found in South Asia
  • Haplogroup M41b - found in Andhra Pradesh, India
  • Haplogroup M41c - found in Andrah Pradesh, India
• Haplogroup M42 - found among Australian Abrorigines
• Haplogroup M48 - rare clade found at least in Saudi Arabia
• Haplogroup D - found in Eastern Eurasia, Native Americans, Central Asia and occasionally also in West Asia and Northern Europe.
• Haplogroup G - found especially in Japan with some isolated instances in diverse places of Asia
• Haplogroup Q - found in Melanesia and Australia (Aborigines)

References

1. ^ Rajkumar et al. (2005), Phylogeny and antiquity of M macrohaplogroup inferred from complete mt DNA sequence of Indian specific lineages, BMC Evolutionary Biology 2005, 5:26 doi:10.1186/1471-2148-5-26
2. ^ Gonzalez et al. (2007), Mitochondrial lineage M1 traces an early human backflow to Africa, BMC Genomics 2007, 8:223 doi:10.1186/1471-2164-8-223
3. ^ Chandrasekar et al. (2007), YAP insertion signature in South Asia, Ann Hum Biol. 2007 Sep-Oct;34(5):582-6.
4. ^ Quintana et al. (1999), Genetic evidence of an early exit of Homo sapiens sapiens from Africa through eastern Africa, 1: Nat Genet. 1999 Dec;23(4):437-41.
5. Semino et al. (2000), The Genetic Legacy of Paleolithic Homo sapiens in Extant Europeans: A Y Chromosome Perspective, Science. 2000 Nov 10;290(5494):1155-9.
6. ^ Kivisild; et al. (2003). "The Genetic Heritage of the Earliest Settlers Persists Both in Indian Tribal and Caste Populations". {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |last= (help)
7. ^ Metspalu et al. year=2004. "Most of the extant mtDNA boundaries in South and Southwest Asia were likely shaped during the initial settlement of Eurasia by anatomically modern humans". {{cite journal}}: Cite journal requires |journal= (help); Missing pipe in: |last= (help)CS1 maint: numeric names: authors list (link)
8. ^ Macaulay; et al. (2005). "Single, Rapid Coastal Settlement of Asia Revealed by Analysis of Complete Mitochondrial Genomes" (PDF). doi:10.1126/science.1109792. {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |last= (help)
9. ^ Sun et al. (2006), The Dazzling Array of Basal Branches in the mtDNA Macrohaplogroup M from India as Inferred from Complete Genomes, Molecular Biology and Evolution 2006 23(3):683-690; doi:10.1093/molbev/msj078
10. ^ Thangaraj et al. (2006), In situ origin of deep rooting lineages of mitochondrial Macrohaplogroup 'M' in India, BMC Genomics 2006, 7:151
11. ^ Olivieri et al. (2006), The mtDNA legacy of the Levantine early Upper Palaeolithic in Africa, Science. 2006 Dec 15;314(5806):1767-70
12. Coudray; et al. (2008). "The Complex and Diversified Mitochondrial Gene Pool of Berber Populations". doi:10.1111/j.1469-1809.2008.00493.x. {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |last= (help)
13. Gonzalez et al.,Mitochondrial lineage M1 traces an early human backflow to Africa, BMC Genomics 2007, 8:223 doi:10.1186/1471-2164-8-223
14. Hudjashov, Kivisild; et al. (2007). "Revealing the prehistoric settlement of Australia by Y chromosome and mtDNA analysis". {{cite journal}}: Cite journal requires |journal= (help); Explicit use of et al. in: |last= (help)
15. Ghezzi et al. (2005), Mitochondrial DNA haplogroup K is associated with a lower risk of Parkinson's disease in Italians, European Journal of Human Genetics (2005) 13, 748–752.
16. Edwin et al. (2002), Mitochondrial DNA diversity among five tribal populations of southern India, CURRENT SCIENCE, VOL. 83, NO. 2, 25 JULY 2002
17. Comas et al. (2004), Admixture, migrations, and dispersals in Central Asia: evidence from maternal DNA lineages, European Journal of Human Genetics (2004) 12, 495–504.

See also

• Human mitochondrial DNA haplogroups
• Human mitochondrial genetics
• Genetics and Archaeogenetics of South Asia

External links

• Spread of Haplogroup M, from National Geographic

• Tree of M haplogroup as for 2006

• Haplogroup M (mtDNA) interest group on Facebook

• China DNA interest group on Facebook

• The India DNA geographical project at Family Tree DNA

• The China DNA geographical project at Family Tree DNA

• Another tree emphasizing the Andamanese and Nicobarese populations in comparison with other peoples with high M presence

• K.Tharanghaj et al. In situ origin of deep rooting lineages of mitochondrial Macrohaplogroup M in India (PDF document)

• Human mtDNA haplogroups
• Recent single origin hypothesis