Mitochondrial Footprints of Human Expansions in Africa

School of Biological Sciences, Massey University, Palmerston North, New Zealand.
The American Journal of Human Genetics (Impact Factor: 10.93). 10/1997; 61(3):691-704. DOI: 10.1086/515503
Source: PubMed

ABSTRACT mtDNA studies support an African origin for modern Eurasians, but expansion events within Africa have not previously been investigated. We have therefore analyzed 407 mtDNA control-region sequences from 13 African ethnic groups. A number of sequences (13%) were highly divergent and coalesced on the "mitochondrial Eve" in Africans. The remaining sequences also ultimately coalesced on this sequence but fell into four major clusters whose starlike phylogenies testify to demographic expansions. The oldest of these African expansions dates to approximately 60,000-80,000 years ago. Eurasian sequences are derived from essentially one sequence within this ancient cluster, even though a diverse mitochondrial pool was present in Africa at the time.

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Available from: Martin Richards, Sep 28, 2015
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    • "Within Africa , a number of mtDNA lineages have been associated with various stages of the Bantu dispersals , including subsets of L0a ( Pereira et al . 2001 ; Watson et al . 1997 ) , L1c ( Batini et al . 2007 ; Salas et al . 2002 ) , L2a ( Pereira et al . 2001 ; Salas et al . 2002 ) , L3b ( Salas et al . 2002 ; Soares et al . 2012 ; Watson et al . 1997 ) and L3e ( Ban - delt et al . 2001 ; Pereira et al . 2001 ; Plaza et al . 2004 ; Salas"
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    ABSTRACT: The Great Lakes lie within a region of East Africa with very high human genetic diversity, home of many ethno-linguistic groups usually assumed to be the product of a small number of major dispersals. However, our knowledge of these dispersals relies primarily on the inferences of historical, linguistics and oral traditions, with attempts to match up the archaeological evidence where possible. This is an obvious area to which archaeogenetics can contribute, yet Uganda, at the heart of these developments, has not been studied for mitochondrial DNA (mtDNA) variation. Here, we compare mtDNA lineages at this putative genetic crossroads across 409 representatives of the major language groups: Bantu speakers and Eastern and Western Nilotic speakers. We show that Uganda harbours one of the highest mtDNA diversities within and between linguistic groups, with the various groups significantly differentiated from each other. Despite an inferred linguistic origin in South Sudan, the data from the two Nilotic-speaking groups point to a much more complex history, involving not only possible dispersals from Sudan and the Horn but also large-scale assimilation of autochthonous lineages within East Africa and even Uganda itself. The Eastern Nilotic group also carries signals characteristic of West-Central Africa, primarily due to Bantu influence, whereas a much stronger signal in the Western Nilotic group suggests direct West-Central African ancestry. Bantu speakers share lineages with both Nilotic groups, and also harbour East African lineages not found in Western Nilotic speakers, likely due to assimilating indigenous populations since arriving in the region ~3000 years ago.
    Human Genetics 07/2015; 134(9). DOI:10.1007/s00439-015-1583-0 · 4.82 Impact Factor
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    • "Similar transient increases in Neanderthal population densities may account for the irregular manifestation of symbolic expression in the European Mousterian (compare the temporal pattern of Mousterian innovation in Langley, Clarkson, and Ulm 2008 with Mousterian site abundance evidence of Neanderthal population density in Stringer et al. 2003 and Lahr and Foley 2003). Later population expansion in Africa beginning in the late MSA (80–70 Ka BP) and continuing into the LSA/UP, as reflected in both genetic (Excoffier and Schneider 1999; Forster 2004; Harpending et al. 1993; Watson et al. 1997) and archeological evidence (Mellars and French 2011; Steele and Klein 2005; Stiner et al. 1999), produced population densities sufficient for a high rate of CTE, and thus demographic factors, rather than cognitive capabilities, might account for the persistent expression of behavioral modernity in the LSA and UP (Powell, Shennan, and Thomas 2009; Shennan 2001). "
    Current Anthropology 01/2014; 55(4):434-435. · 2.93 Impact Factor
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    • "Intriguingly, the time of arrival of L0a’b in eastern Africa is close to the time of expansion of haplogroup L3. L3 arose in eastern Africa and was the first mtDNA lineage to undergo a major population expansion, both westwards into central Africa and eastwards out of Africa, ~60 ka [24,33]. One possibility is that these dispersals may have been connected to the arrival the people carrying L0a’b. "
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    ABSTRACT: The emergence of more refined chronologies for climate change and archaeology in prehistoric Africa, and for the evolution of human mitochondrial DNA (mtDNA), now make it feasible to test more sophisticated models of early modern human dispersals suggested by mtDNA distributions. Here we have generated 42 novel whole-mtDNA genomes belonging to haplogroup L0, the most divergent clade in the maternal line of descent, and analysed them alongside the growing database of African lineages belonging to L0's sister clade, L1'6. We propose that the last common ancestor of modern human mtDNAs (carried by "mitochondrial Eve") possibly arose in central Africa ~180 ka, at a time of low population size. By ~130 ka two distinct groups of anatomically modern humans co-existed in Africa: broadly, the ancestors of many modern-day Khoe and San populations in the south and a second central/eastern African group that includes the ancestors of most extant worldwide populations. Early modern human dispersals correlate with climate changes, particularly the tropical African "megadroughts" of MIS 5 (marine isotope stage 5, 135-75 ka) which paradoxically may have facilitated expansions in central and eastern Africa, ultimately triggering the dispersal out of Africa of people carrying haplogroup L3 ~60 ka. Two south to east migrations are discernible within haplogroup LO. One, between 120 and 75 ka, represents the first unambiguous long-range modern human dispersal detected by mtDNA and might have allowed the dispersal of several markers of modernity. A second one, within the last 20 ka signalled by L0d, may have been responsible for the spread of southern click-consonant languages to eastern Africa, contrary to the view that these eastern examples constitute relicts of an ancient, much wider distribution.
    PLoS ONE 11/2013; 8(11):e80031. DOI:10.1371/journal.pone.0080031 · 3.23 Impact Factor
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