sub-Saharan origin of the Greeks
Department of Immunology and Molecular Biology, H. 12 de Octubre, Universidad Complutense, Madrid, Spain.
http://www.ncbi.nlm.nih.gov/pubmed/11260506?dopt=Citation
As reviewed in the Introduction, Sicily has been subject to many different colonization episodes during pre-historical and historical times. The internal STR stratification of the E3b1a-M78 Hg reveals a certain amount of population structuring in the island, which is consistent with the successive presence of several different human populations. Specifically, some signatures of gene flows from Greece and from northern Africa can be identified.
The lineage E3b1a2-V13 13-13-30-24-10-11-13, which is typical of the Greek and southern Balkan regions, is present in the eastern side of the island and, together with the more general presence of the E3b1a2-V13 lineages, supports the presence of a common genetic heritage shared by the Sicilians and the Greeks. The TMRCA estimate of 2380 years BP, based on the STR lineages of the same E3b1a2-V13 Hg, coincides with the peak of the Greek classic era in Sicily, even if the very wide CI – a common result in such a kind of time estimates – however, we cannot exclude alternative hypotheses, for example an earlier arrivals of some of the E3b1a2-V13 chromosomes in Sicily from neolithic farmers.
We found a homogenous distribution of the E3b1a2-V13 marker over the island, which suggests an impact of the Greek colonization so impressive as to create a uniform stratum across Sicily. The Hg E3b1a2-V13 is estimated to contribute to the Sicilian gene pool by a fraction reaching 37%.
These data are compatible with the hypothesis that the largest historical demographic impact on Sicilian population was by the Greek settlers. A non-trivial question to raise for making this interpretation more plausible is whether the Greek colonies were of such size to lead to the diffusion of their genes. Because of the privileged position of Greece as ‘the door’ from the Near East to the Mediterranean, by the end of the Bronze Age the average density of the population was higher in Greece than in Europe by a factor of 3:3.7 inhabitants per square kilometre.34 Between 1000 and 400 BC, the population doubled in Europe, increasing from 10 to 20 million. In the same period the population trebled in Greece, reaching a total of 3 million. Around 400 BC Italy, the second most densely populated country in Europe after Greece, had about 4 million people.34 The Greek colonies of Sicily alone accounted for 1.5 million people, of which more than 10% (about 200 000) were of Greek origin.34, 35 To these Greek inhabitants of Sicily may be added at least another 100 000 Greek colonizers in southern Italy, so that before the Roman period, one in every 10–13 inhabitants in southern Italy was Greek.35 Admittedly these estimates must be taken with caution; however, their order of magnitude does not contradict the hypothesis of a possible introduction of Y lineages associated with Greek migration in ESI and in southern Italy.
The Hg E3b1b-M81, widely diffused in northwestern African populations, is estimated to contribute to the Sicilian gene pool at a rate of 6%. The distribution of E3b1b-M81 chromosomes in Africa closely matches the areas of distribution of Berber speaking populations, suggesting close Hg-ethnicity specificity. Interestingly, haplotype 13-14-30-24-9-11-13, associated to the E3b1b-M81 chromosomes,23, 36 is also present in Sicily. On the basis of the YHRD database, this haplotype occurs with high frequency in the Berber population of Tunisia, whereas it is less common elsewhere in North Africa.23, 37 The co-presence in Sicily of this haplotype and of the E3b1a1-V12, E3b1a3-V22, E3b1a4-V65 and J1-M267 Hgs could be attributed to the gene flows occurred during several trans-Mediterranean migrations from Africa, including the Arab invasion by sea.7, 12
The frequency of the R1b1c-M269 Hg, particularly high in some samples of WSI, is another interesting feature of the Sicilian paternal gene pool. This could be the legacy of the chromosomes coming from other parts of Europe. Moreover, Hgs I-M170, I1a-M253 and I1b2a-M223 are more represented in the northwestern area of the island than in the eastern area. Equally noteworthy is that the J2 chromosomes in WSI are also DYS445-6.
These differences lead us to a discussion of the genetic heterogeneity between areas of ESI and WSI. Such heterogeneity was previously emphasized on the study of the haemoglobinopathies,38 non-DNA polymorphisms,2 the autosomal microsatellites5 and surnames.8
In the present research, such heterogeneity is confirmed by the significantly different distribution of the frequencies of the main Hgs HgE, HgJ, HgI, HgG, R1b1c-M269 and R1a1-M17 and by the results from principal component analysis of such frequencies when compared to those from other parts of southern Europe and the Mediterranean, but weakly supported by a more sophisticated AMOVA analysis. This result is likely to be the effect of the contribution of different populations and repeated founder effects and it highlights the complex histories of settlement in this island.
The general heterogeneous composition of Hgs seen in our Sicilian data is consistent with similar patterns observed in other major islands of the Mediterranean, like Sardinia (gene diversity 0.801±0.010 SD on 939 samples using 23 Hgs)39 and Crete29, 40 (gene diversity 0.926±0.0006 SD on 193 samples using 29 Hgs),29 possibly reflecting the complex histories of settlements in these islands during the Holocene (Supplementary Table 1).
http://www.nature.com/ejhg/journal/v17/n1/full/ejhg2008120a.html
