Variation in the human mitochondrial genome (mtDNA) is now routinely described and used to infer the histories of peoples, by means of one of two procedures, namely, the assaying of RFLPs throughout the genome and the sequencing of parts of the control region (CR). Using 95 samples from the Near East and northwest Caucasus, we present an analysis based on both systems, demonstrate their concordance, and, using additional available information, present the most refined phylogeny to date of west Eurasian mtDNA. We describe and apply a nomenclaturefor mtDNA clusters. Hypervariable nucleotides are identified, and the relative mutation rates ofthe two systems are evaluated. We point out where ambiguities remain. The identification of signature mutations for each cluster leads us to apply a hierarchical scheme for determining the cluster composition of a sample of Berber speakers, previously analyzed only for CR variation. We show that the main indigenous North African cluster is a sister group to the most ancient cluster of European mtDNAs, from which it diverged »50,000 years ago.
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An advantage of the resolution of the U6 cluster is that an age estimate now can be made by use of the r statistic (Forster et al. 1996), although this is extremely provisional because the genealogy of U6 is far from starlike. For all sequences with motif 16172–16219 from the studies by Di Rienzo and Wilson (1991), Coˆ rte-Real et al. (1996), Pinto et al. (1996), and Watson et al. (1997), we estimated the time to the ancestral sequence by using a mutation rate of 1 in 20,180 years (Forster et al. 1996). The value of r for these data is 2.53, which converts to an age of 51,000 years, with a central 95% credible region of 42,500–60,500 years. Since this credible region was derived under the assumption of a starlike genealogy, its width surely is underestimated. Nevertheless, it is suggestive that the age estimate is similar to that of U5, the oldest European-specific cluster, and congruent with archaeological dates for the arrival of anatomically modern humans with Upper Paleolithic (Dabban) industry in Cyrenaı¨ca, which is believed to predate 40,000 years ago (Close and Wendorf 1990). This suggests a model in which U5 and U6 diverged from a common ancestor (the Cambridge reference sequence [CRS]) in the Near East (where traces remain of U6; Di Rienzo and Wilson 1991; authors’ unpublished data) » 50,000 years ago and spread along the north and south coasts, respectively, of the Mediterranean, as far as Iberia to the north and Cyrenaı¨ca to the south, » 45,000–50,000 years ago.
This model is in accordance with the physical-anthropological view that the aboriginal “Mekta-Afalou” North Africans were closely related to the Cro-Magnon settlers of early Upper Paleolithic Europe (Brett and Fentress 1996). The appearance of the Iberomaurusian industry in the Mahgreb may have been the result of a further pulse of westward expansion at least 22,000 years ago (Close and Wendorf 1990), and population replacement with the arrival of the Epi-Paleolithic Capsian industry, » 9,000 years ago, seems unlikely (Brett and Fentress 1996). A greater number of founder lineages arriving in the first wave of settlement from the Near East would reduce the estimate for the time of settlement, but, at present, there is insufficient evidence for multiple founders, especially given the historical record of interaction (and, therefore, possible gene flow) between North Africa and the Near East. However, because of concordance between the genetic and archaeological dates, the early date proposed here is attractive.
Essentially: the logic is that there is so much variety in the Eurasian origin haplotype U, that it has to have been in North Africa a very long time. the Iberomaurussian seems to have come from a Nubia culture called Wadi Halfa (Halfan culture) which brought microlithic technology Northwards.
Among the 85 Mozabite subjects, there also are five L2 and four L3b sequences—identified on the basis of their HVS I motifs—indicating gene flow from sub-Saharan Africa, and two L3a* sequences, also of sub-Saharan origin (Coˆ rte-Real et al. 1996), indicating a total sub-Saharan component in the Mzab of 14%. This overall picture of high European and little sub-Saharan African input also is reflected in Moroccan and Canary Islander samples.
In summary, one-third of Mozabite Berber mtDNAs have a Near Eastern ancestry, probably having arrived in North Africa »50,000 years ago, and one-eighth have an origin in sub-Saharan Africa. Europe appears to be the source of many of the remaining sequences, with the rest having arisen either in Europe or in the Near East. Since, in Europe, cluster J appears to have accompanied the Neolithic from the Near East (Richards et al. 1996, 1997, 1998), the J sequences in the Berbers possibly may represent a North African route for the spread of the Neolithic from the Near East. With these exceptions, it is entirely feasible that all the European and Near Eastern sequences present in the northern Berbers arrived from Europe within the last 10,000 years. Iberia and the Mediterranean islands, in particular Bronze Age Sicily and Malta, clearly are implicated in this process (Brett and Fentress 1996). However, since the Nile Valley may have played an important role, particularly in the spread of the Berber language (Brett and Fentress 1996), data from this region will also be necessary before a clear picture can emerge.