- Human pathology

Home > Technical section > Biology > Molecular biology > Population genetics > By geographic areas > Africa > Africa


Wednesday 28 September 2005

- Africa presents the most complex genetic picture of any continent, with a time depth for mitochondrial DNA (mtDNA) lineages >100,000 years.

- The most recent widespread demographic shift within the continent was most probably the Bantu dispersals, which archaeological and linguistic evidence suggest originated in West Africa 3,000-4,000 years ago, spreading both east and south. (12395296)

- Southeast Bantu speakers have a composite origin on the maternal line of descent, with approximately 44% of lineages deriving from West Africa, approximately 21% from either West or Central Africa, approximately 30% from East Africa, and approximately 5% from southern African Khoisan-speaking groups. (12395296)

- The ages of the major founder types of both West and East African origin are consistent with the likely timing of Bantu dispersals, with those from the west somewhat predating those from the east. (12395296)

- Despite this composite picture, the southeastern African Bantu groups are indistinguishable from each other with respect to their mtDNA, suggesting that they either had a common origin at the point of entry into southeastern Africa or have undergone very extensive gene flow since. (12395296)

Mitochondrial haplogroups

- Haplogroup L (defined by an African-specific HpaI site gain at nucleotide pair np3592) (7611282)

  • 76% of the African mtDNAs
  • 100% of the Pygmies mtDNAs
  • 67.3% of the Senegalese mtDNAs

- Other haplogroups were observed in the Senegalese. These haplogroups were more similar to those observed in Europeans and Asians than to haplogroup L mtDNAs, suggesting that the African mtDNAs without the HpaI np 3592 site could be the ancestral types from which European and Asian mtDNAs were derived. (7611282)

- Comparison of the intrapopulation sequence divergence in African and non-African populations confirms that African populations exhibit the largest extent of mtDNA variation, a result that further supports the hypothesis that Africans represent the most ancient human group and that all modern humans have a common and recent African origin. (7611282)

- The age of the total African variation was estimated to be 101,000-133,000 years before present (YBP), while the age of haplogroup L was estimated at 98,000-130,000 YBP. These values substantially exceed the ages of all Asian- and European-specific mtDNA haplogroups. (7611282)

- Studies of human mitochondrial (mt) DNA genomes demonstrate that the root of the human phylogenetic tree occurs in Africa. Although 2 mtDNA lineages with an African origin (Haplogroup M and Haplogroup N) were the progenitors of all non-African haplogroups, macrohaplogroup L (including haplogroups L0-L6) is limited to sub-Saharan Africa.

- Several L haplogroup lineages occur most frequently in eastern Africa (e.g., L0a, L0f, L5, and L3g), but some are specific to certain ethnic groups, such as haplogroup lineages L0d and L0k that previously have been found nearly exclusively among southern African "click" speakers.

Eastern Africa

Tanzanians have high genetic diversity and possess ancient mtDNA haplogroups, some of which are either rare (L0d and L5) or absent (L0f) in other regions of Africa. A large and diverse human population could have persisted in eastern Africa and that eastern Africa may have been an ancient source of dispersion of modern humans both within and outside of Africa.

See also

- mtDNA sequence variation
- Africans
- Pygmies
- Mandenkalu
- Wolof
- Pular


- Gonder MK, Mortensen HM, Reed FA, de Sousa A, Tishkoff SA. Whole-mtDNA genome sequence analysis of ancient African lineages. Mol Biol Evol. 2007 Mar;24(3):757-68. PMID: 17194802

- Ramachandran S, Deshpande O, Roseman CC, Rosenberg NA, Feldman MW, Cavalli-Sforza LL. Support from the relationship of genetic and geographic distance in human populations for a serial founder effect originating in Africa. Proc Natl Acad Sci U S A. 2005 Nov 1;102(44):15942-7. PMID: 16243969

- Salas A, Richards M, De la Fe T, Lareu MV, Sobrino B, Sanchez-Diz P, Macaulay V, Carracedo A. The making of the African mtDNA landscape. Am J Hum Genet. 2002 Nov;71(5):1082-111. PMID: 12395296

- Chen YS, Torroni A, Excoffier L, Santachiara-Benerecetti AS, Wallace DC. Analysis of mtDNA variation in African populations reveals the most ancient of all human continent-specific haplogroups. Am J Hum Genet. 1995 Jul;57(1):133-49. PMID: 7611282

- Guglielmino CR, Viganotti C, Hewlett B, Cavalli-Sforza LL. Cultural variation in Africa: role of mechanisms of transmission and adaptation. Proc Natl Acad Sci U S A. 1995 Aug 1;92(16):7585-9. PMID: 11607569