SOCOTRA: DNA AUTOCHTHONOUS EVOLUTION
Очень примечательный материал из газеты "Tayf", издаваемой Обществом друзей Сокотры на английском и арабском языках, от одного из авторов исследования генетических корней сокотрийцев. На этот раз - в популярном изложении, что, однако, все еще не дает полных и исчерпывающих ответов.
"Mitochondrial DNA Reveals Ancestry of Soqotrans
Viktor Černý
The island of Soqotra is highly important for anthropological research. The most straightforward reason to study the Soqotri people is that nothing is really known about their ancient origins. Another is its situation not far from the Horn of Africa, from where anatomically modern humans first colonized Eurasia some 75,000 years ago. As such, it might represent a settlement site of such ancestral “non-Africans”. However, seeing as sea level at that time lay much lower, and that hunter-gatherers were adapted mainly to the low-lying coastal ecosystem, there is only a very small chance of revealing unequivocal archaeological proof dating from such a very ancient migration*. The genetic material of the extant population, is, however, easily accessible.
A team of Yemeni, Czech, Portuguese and United States researchers started the first archaeogenetic investigation of the Soqotra Island in 2006. Thanks to the very kind collaboration of local people we were able to secure the material for such a study and to compare the first mitochondrial DNA sequences of the Soqotri people with the currently known phylogenetic system worldwide. In fact, we found very little African influence among the indigenous people of the island. The population likely experienced several founder effects but very close relations to Yemeni mitochondrial diversity are still quite clearly detectable.
Moreover, the Soqotri data show evidence of autochthonous evolution, especially at the level of the mitochondrial haplogroup (a group of phylogenetically related sequences) known in the worldwide system as haplogroup R0a. This haplogroup is otherwise frequently also found in Arabia and Northeast Africa; however, we have identified, within the Soqotra R0a, two distinctive clades quite specific for the island and adjacent regions. The first one has never been found anywhere else in the world except for one case from Al-Mahra; we classified it as R0a1a1a. According to our calculations the origin of this specific clade corresponds with the period of some 4,000 years ago. The second Soqotri clade can be classified as R0a2f1 and is slightly older with its beginnings calculated at almost 6,000 years ago. Apart from Soqotra it was located only in adjacent regions such as Al-Mahra and Hadramawt. Geographic specificity of these unique mitochondrial clades suggests a population expansion that was enabled by favorable climatic conditions during early stages of the Holocene.
It thus seems that the main population boom in Soqotra was quite recent and might be related to the differentiation of South Arabian languages. That is not to say there are no traces of the first migration ‘Out-of-Africa’ in Soqotra, but we have not as yet identified any. In fact, there are some other rare sequences in Soqotra that will deserve closer attention. However, it is now more certain that more recent periods of population inputs from South Arabia had a much more important impact on the population history of the extant Soqotri people."
Tayf No.7 May 2010, p. 19
"Mitochondrial DNA Reveals Ancestry of Soqotrans
Viktor Černý
The island of Soqotra is highly important for anthropological research. The most straightforward reason to study the Soqotri people is that nothing is really known about their ancient origins. Another is its situation not far from the Horn of Africa, from where anatomically modern humans first colonized Eurasia some 75,000 years ago. As such, it might represent a settlement site of such ancestral “non-Africans”. However, seeing as sea level at that time lay much lower, and that hunter-gatherers were adapted mainly to the low-lying coastal ecosystem, there is only a very small chance of revealing unequivocal archaeological proof dating from such a very ancient migration*. The genetic material of the extant population, is, however, easily accessible.
A team of Yemeni, Czech, Portuguese and United States researchers started the first archaeogenetic investigation of the Soqotra Island in 2006. Thanks to the very kind collaboration of local people we were able to secure the material for such a study and to compare the first mitochondrial DNA sequences of the Soqotri people with the currently known phylogenetic system worldwide. In fact, we found very little African influence among the indigenous people of the island. The population likely experienced several founder effects but very close relations to Yemeni mitochondrial diversity are still quite clearly detectable.
Moreover, the Soqotri data show evidence of autochthonous evolution, especially at the level of the mitochondrial haplogroup (a group of phylogenetically related sequences) known in the worldwide system as haplogroup R0a. This haplogroup is otherwise frequently also found in Arabia and Northeast Africa; however, we have identified, within the Soqotra R0a, two distinctive clades quite specific for the island and adjacent regions. The first one has never been found anywhere else in the world except for one case from Al-Mahra; we classified it as R0a1a1a. According to our calculations the origin of this specific clade corresponds with the period of some 4,000 years ago. The second Soqotri clade can be classified as R0a2f1 and is slightly older with its beginnings calculated at almost 6,000 years ago. Apart from Soqotra it was located only in adjacent regions such as Al-Mahra and Hadramawt. Geographic specificity of these unique mitochondrial clades suggests a population expansion that was enabled by favorable climatic conditions during early stages of the Holocene.
It thus seems that the main population boom in Soqotra was quite recent and might be related to the differentiation of South Arabian languages. That is not to say there are no traces of the first migration ‘Out-of-Africa’ in Soqotra, but we have not as yet identified any. In fact, there are some other rare sequences in Soqotra that will deserve closer attention. However, it is now more certain that more recent periods of population inputs from South Arabia had a much more important impact on the population history of the extant Soqotri people."
Tayf No.7 May 2010, p. 19