Haplogroup N is a human mitochondrial DNA (mtDNA) clade. A macrohaplogroup, its descendant lineages are distributed across many continents. Like its sibling macrohaplogroup M, macrohaplogroup N is a descendant of the haplogroup L3. All mtDNA haplogroups found outside of Africa are descendants of either haplogroup N or its sibling haplogroup M. M and N are the signature maternal haplogroups that define the theory of the recent African origin of modern humans and subsequent early human migrations around the world. The global distribution of haplogroups N and M indicates that there was likely at least one major prehistoric migration of humans out of Africa, with both N and M later evolving outside the continent.

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: A study (Vai et al. 2019), finds a basal branch of maternal haplogroup N in early Neolithic North African remains from the Libyan site of Takarkori. The authors propose that N most likely split from L3 in the Arabian peninsula and later migrated back to North Africa, with its sister haplogroup M also likely splitting from L3 in the Middle East, but also suggest that N may have possibly diverged in North Africa, and state that more information is necessary to be certain.

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. In 2019, a study by Vai et al. presented evidence of a basal branch of haplogroup N from the Neolithic Sahara. They suggest that N either diverged from haplogroup L3 in the Near East (possibly in the Arabian peninsula, following the exit of L3 from Africa), then back-migrated to North Africa, or that it instead may have originated in North Africa (having diverged from L3 there).

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.

Subgroups distribution

Haplogroup N's derived clades include the macro-haplogroup R and its descendants, and haplogroups A, I, S, W, X, and Y. Rare unclassified haplogroup N* has been found among fossils belonging to the Cardial and Epicardial culture (Cardium pottery) and the Pre-Pottery Neolithic B. A rare unclassified form of N has been also been reported in modern Algeria.

Subclades

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.