The Expansion of mtDNA Haplogroup L3 within and out of Africa

Mol Biol Evol. 2012 Mar;29(3):915-27. doi: 10.1093/molbev/msr245. Epub 2011 Nov 16.

Abstract

Although fossil remains show that anatomically modern humans dispersed out of Africa into the Near East ∼100 to 130 ka, genetic evidence from extant populations has suggested that non-Africans descend primarily from a single successful later migration. Within the human mitochondrial DNA (mtDNA) tree, haplogroup L3 encompasses not only many sub-Saharan Africans but also all ancient non-African lineages, and its age therefore provides an upper bound for the dispersal out of Africa. An analysis of 369 complete African L3 sequences places this maximum at ∼70 ka, virtually ruling out a successful exit before 74 ka, the date of the Toba volcanic supereruption in Sumatra. The similarity of the age of L3 to its two non-African daughter haplogroups, M and N, suggests that the same process was likely responsible for both the L3 expansion in Eastern Africa and the dispersal of a small group of modern humans out of Africa to settle the rest of the world. The timing of the expansion of L3 suggests a link to improved climatic conditions after ∼70 ka in Eastern and Central Africa rather than to symbolically mediated behavior, which evidently arose considerably earlier. The L3 mtDNA pool within Africa suggests a migration from Eastern Africa to Central Africa ∼60 to 35 ka and major migrations in the immediate postglacial again linked to climate. The largest population size increase seen in the L3 data is 3-4 ka in Central Africa, corresponding to Bantu expansions, leading diverse L3 lineages to spread into Eastern and Southern Africa in the last 3-2 ka.

Publication types

  • Historical Article
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa
  • African Continental Ancestry Group / genetics
  • Base Sequence
  • Bayes Theorem
  • DNA, Mitochondrial / genetics*
  • Emigration and Immigration / history*
  • Evolution, Molecular*
  • Haplotypes / genetics*
  • History, Ancient
  • Humans
  • Likelihood Functions
  • Models, Genetic
  • Molecular Sequence Data
  • Phylogeny*
  • Phylogeography
  • Population Density
  • Population Dynamics*
  • Sequence Analysis, DNA

Substances

  • DNA, Mitochondrial