The Arabian Cradle: Mitochondrial Relicts of the First Steps along the Southern Route out of Africa

Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Portugal.
The American Journal of Human Genetics (Impact Factor: 10.93). 02/2012; 90(2):347-55. DOI: 10.1016/j.ajhg.2011.12.010
Source: PubMed


A major unanswered question regarding the dispersal of modern humans around the world concerns the geographical site of the first human steps outside of Africa. The "southern coastal route" model predicts that the early stages of the dispersal took place when people crossed the Red Sea to southern Arabia, but genetic evidence has hitherto been tenuous. We have addressed this question by analyzing the three minor west-Eurasian haplogroups, N1, N2, and X. These lineages branch directly from the first non-African founder node, the root of haplogroup N, and coalesce to the time of the first successful movement of modern humans out of Africa, ∼60 thousand years (ka) ago. We sequenced complete mtDNA genomes from 85 Southwest Asian samples carrying these haplogroups and compared them with a database of 300 European examples. The results show that these minor haplogroups have a relict distribution that suggests an ancient ancestry within the Arabian Peninsula, and they most likely spread from the Gulf Oasis region toward the Near East and Europe during the pluvial period 55-24 ka ago. This pattern suggests that Arabia was indeed the first staging post in the spread of modern humans around the world.

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    • "Fernandes et al. (2012) note that basal lineages of macrohaplogroup N (e.g., N1, N2, and X) are present throughout the Near East and neighboring portions of Africa but appear concentrated specifically within Arabia. These lineages have been dated to around 60 kya, and it has been suggested that they are related to the OOA migration; however, these clades are spread over much of the Near East and are not specific to Yemen or the Horn of Africa/ southern Arabia region (Fernandes et al., 2012). Also, an analysis of nuclear SNP data suggested there were older migrations back into the Horn of Africa that date to at least 23 kya; however, these migrations could not be dated due to the limitations of nuclear data (Hodgson et al., 2014). "
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    • "Fig . 1 ; supplemental Table S1 ) . This is reflected in a sub - stantial Eurasian autosomal component in Eastern Africa , which is also evident to some extent in Kenya ( Pagani et al . 2012 ) . Due to deep ancestry and the distribution of these lineages ( Abu - Amero et al . 2008 ; Brakez et al . 2001 ; Černý et al . 2008 ; Coudray et al . 2009 ; Fernandes et al . 2012 ; Kivisild et al . 2004 ; Olivieri et al . 2006 ; Rhouda et al . 2009 ; Richards et al . 2000 , 2003 ) , none of the West Eurasian mtDNAs found in Uganda has a likely European source , for example , resulting from the heavy European colonial involvement since the 1870s ( Maxon 2009 ) . One possibility is a Bronze - Age dispersal from th"
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    • "Slow mutation rates yield older dates of divergence and fast mutation rates yield younger dates. For example, estimates from modern human genetic data have ranged between ~84 and 44 ka from mtDNA data (Macaulay et al., 2005; Endicott and Ho, 2008; Endicott et al., 2009; Fernandes et al., 2012; Lippold et al., 2014); ~120 and 60 ka from Y-chromosome data (Lippold et al., 2014; Scozzari et al., 2014), and ~140 and 65 ka from nuclear data (Gutenkunst et al., 2009; Xing et al., 2010; Eriksson et al., 2012; Scally and Durbin, 2012; Reyes-Centeno et al., 2014). Calibration with fossil genomes has now served to constrain these rates for the recent human lineage (Fu et al., 2013b, 2014; Rieux et al., 2014). "
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