Haplogroup N (mtDNA)

Origins

There is widespread agreement in the scientific community concerning the African ancestry of haplogroup L3 (haplogroup N's parent clade). However, whether or not the mutations which define haplogroup N itself first occurred within Asia or Africa has been a subject for ongoing discussion and study.

The out of Africa hypothesis has gained generalized consensus. However, many specific questions remain unsettled. To know whether the two M and N macrohaplogroups that colonized Eurasia were already present in Africa before the exit is puzzling.

Torroni et al. 2006 state that Haplogroups M, N and R occurred somewhere between East Africa and the Persian Gulf.

Also related to the origins of haplogroup N is whether ancestral haplogroups M, N and R were part of the same migration out of Africa, or whether Haplogroup N left Africa via the Northern route through the Levant, and M left Africa via Horn of Africa. This theory was suggested because haplogroup N is by far the predominant haplogroup in Western Eurasia, and haplogroup M is absent in Western Eurasia, but is predominant in India and is common in regions East of India. However, the mitochondrial DNA variation in isolated "relict" populations in southeast Asia and among Indigenous Australians supports the view that there was only a single dispersal from Africa. Southeast Asian populations and Indigenous Australians all possess deep rooted clades of both haplogroups M and N. The distribution of the earliest branches within haplogroups M, N, and R across Eurasia and Oceania therefore supports a three-founder-mtDNA scenario and a single migration route out of Africa. These findings also highlight the importance of Indian subcontinent in the early genetic history of human settlement and expansion.

Asian origin hypothesis

The hypothesis of Asia as the place of origin of haplogroup N is supported by the following:

1. Haplogroup N is found in all parts of the world but has low frequencies in Sub-Saharan Africa. According to a number of studies, the presence of Haplogroup N in Africa is most likely the result of back migration from Eurasia.
2. The oldest clades of macrohaplogroup N are found in Asia and Australia.
3. It would be paradoxical that haplogroup N had traveled all the distance to Australia or New World yet failed to affect other populations within Africa besides North Africans and Horn Africans.
4. N1 is the only sub-clade of haplogroup N that has been observed in Africa. However N1a is the only one in East Africa: this haplogroup is even younger and is not restricted to Africa, N1a has also been detected in Southern Siberia and was found in a 2,500-year-old Scytho-Siberian burial in the Altai region.
5. The mitochondrial DNA variation in isolated "relict" populations in southeast Asia supports the view that there was only a single dispersal from Africa. The distribution of the earliest branches within haplogroups M, N, and R across Eurasia and Oceania provides additional evidence for a three-founder-mtDNA scenario and a single migration route out of Africa. These findings also highlight the importance of Indian subcontinent in the early genetic history of human settlement and expansion. Therefore, N’s history is similar to M and R which have their most probably origin in South Asia.

African origin hypothesis

According to Toomas Kivisild "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.

Distribution

Haplogroup N is derived from the ancestral L3 macrohaplogroup, which represents the migration discussed in the theory of the recent African origin of modern humans. Haplogroup N is the ancestral haplogroup to almost all clades today distributed in Europe and Oceania, as well as many found in Asia and the Americas. It is believed to have arisen at a similar time to haplogroup M. Haplogroup N subclades like haplogroup U6 are also found at moderate to low frequencies in the Northwest and Northeast Africa due to a back migration from the Near East around 27,000 years ago. U6 has been found among Iberomaurusian specimens in Taforalt.

The N1b subclade has been observed in an ancient individual belonging to the Natufian culture.

In popular science

In the book The Real Eve, Stephen Oppenheimer refers to haplogroup N as "Nasreen" as haplogroup N may have arisen near the Persian Gulf. In his popular book The Seven Daughters of Eve, Bryan Sykes named the originator of this mtDNA haplogroup "Naomi".

Subgroups distribution

Haplogroup N's derived clades include the macro-haplogroup R (and its descendants) and haplogroups A, I, S, W, X, and Y.

Basal N* occurs at its highest frequencies among the Socotri (24.3%).

Undifferentiated haplogroup N is especially common in the Horn of Africa, constituting around 20% of maternal lineages among Somalis. It is also found at low frequencies among Algerians and Reguibate Sahrawi.

Additionally, there are some unnamed N* lineages in South Asia, among indigenous Australians and the Ket people of central Siberia.

Tree

This phylogenetic tree of haplogroup N 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.