Lacan et al., who tested the Neolithic site of Treilles in Southwest France (G2a + I2a) published a new study on Neolithic Spain. The samples are 2000 years older than in Treilles, and identified both G2a and E-V13. This could either confirm a Neolithic origin of E-V13 or, my recent proposal that E1b1b crossed from Africa to Europe before the Neolithic. Spain is indeed the most likely point of entry from North Africa, along with South Italy.
Considering that a substantial percentage of Neolithic mtDNA in Iberia is African (L1b1, L2, L3, respectively in Andalusia, Navarra and Valencia), this could indeed be a sign of a direct migration from North Africa. My hypothesis is that this migration was due to the desertification of the Sahara at the end of the last Ice Age.
Another interesting point is that they mention that the mitochondrial lineages are mostly pre-Neolithic. If Neolithic farmers kept marrying local girls (from the hunter-gatherer community), that would explain why West Asian autosomal genes diminish gradually as we move further away from the Middle East. That may be why there is so little West Asian admixture in Iberia and Sardinia despite the relatively high percentage of G2a.
EDIT : The individuals results are as follow :
- Y-DNA : five G2a men and one E-V13. All confirmed by SNP test except one G2a.
- mtDNA : three K1a, two T2b, one H3 and one U5.
The E-V13 man is the mtDNA U5.
I can't see why Lacan et al. think that these maternal lineages are pre-Neolithic, except for the U5 and H3.
Mt-haplogroup K, and K1a in particular, is so far the most overrepresented among Neolithic samples (16%) compared to the present-day population. This is exactly the frequency observed today in the Levant and in Kurdistan (Georgia is also high with 11%). This makes of mtDNA K one of the most distinctive Near Eastern marker, the maternal equivalent of G2a.
Mt-haplogroup T has never been found in Europe prior to the Neolithic (except for one sample in the Pitted Ware Culture, which is actually contemporary of the Late Chalcolithic and early Bronze Age elsewhere in Europe). There is an interesting inversion of frequency between mtDNA hg J and T in the early and late Neolithic. Based on the current data (247 samples), the frequency of hg T dropped from over 19% in the Early Neolithic to only 4.5% the Late Neolithic, then up again to 10.5% in the Bronze Age (similar level to today).
Considering that a substantial percentage of Neolithic mtDNA in Iberia is African (L1b1, L2, L3, respectively in Andalusia, Navarra and Valencia), this could indeed be a sign of a direct migration from North Africa. My hypothesis is that this migration was due to the desertification of the Sahara at the end of the last Ice Age.
Lacan et al. said:The impact of the Neolithic dispersal on the western European populations is subject to continuing debate. To trace and date genetic lineages potentially brought during this transition and so understand the origin of the gene pool of current populations, we studied DNA extracted from human remains excavated in a Spanish funeral cave dating from the beginning of the fifth millennium B.C. Thanks to a “multimarkers” approach based on the analysis of mitochondrial and nuclear DNA (autosomes and Y-chromosome), we obtained information on the early Neolithic funeral practices and on the biogeographical origin of the inhumed individuals. No close kinship was detected. Maternal haplogroups found are consistent with pre-Neolithic settlement, whereas the Y-chromosomal analyses permitted confirmation of the existence in Spain approximately 7,000 y ago of two haplogroups previously associated with the Neolithic transition: G2a and E1b1b1a1b. These results are highly consistent with those previously found in Neolithic individuals from French Late Neolithic individuals, indicating a surprising temporal genetic homogeneity in these groups. The high frequency of G2a in Neolithic samples in western Europe could suggest, furthermore, that the role of men during Neolithic dispersal could be greater than currently estimated.
Another interesting point is that they mention that the mitochondrial lineages are mostly pre-Neolithic. If Neolithic farmers kept marrying local girls (from the hunter-gatherer community), that would explain why West Asian autosomal genes diminish gradually as we move further away from the Middle East. That may be why there is so little West Asian admixture in Iberia and Sardinia despite the relatively high percentage of G2a.
EDIT : The individuals results are as follow :
- Y-DNA : five G2a men and one E-V13. All confirmed by SNP test except one G2a.
- mtDNA : three K1a, two T2b, one H3 and one U5.
The E-V13 man is the mtDNA U5.
I can't see why Lacan et al. think that these maternal lineages are pre-Neolithic, except for the U5 and H3.
Mt-haplogroup K, and K1a in particular, is so far the most overrepresented among Neolithic samples (16%) compared to the present-day population. This is exactly the frequency observed today in the Levant and in Kurdistan (Georgia is also high with 11%). This makes of mtDNA K one of the most distinctive Near Eastern marker, the maternal equivalent of G2a.
Mt-haplogroup T has never been found in Europe prior to the Neolithic (except for one sample in the Pitted Ware Culture, which is actually contemporary of the Late Chalcolithic and early Bronze Age elsewhere in Europe). There is an interesting inversion of frequency between mtDNA hg J and T in the early and late Neolithic. Based on the current data (247 samples), the frequency of hg T dropped from over 19% in the Early Neolithic to only 4.5% the Late Neolithic, then up again to 10.5% in the Bronze Age (similar level to today).
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