posted
I've always questioned whether Yemenis[ancient Sabaeans?] really were the source population for Y haplogroup J lineages and the West Eurasian mtDNA lineages present in Ethiopia, since so many geneticists like to link to the two to Sabaean influence in Aksumite times, but according to Toomas Kivisild, this may not be the case, at least maternally:
Am. J. Hum. Genet. 75:752–770, 2004 752 Ethiopian Mitochondrial DNA Heritage: Tracking Gene Flow Across and Around the Gate of Tears
"Several mtDNA haplogroups—such as (preHV)1, U6, and some subbranches of L3 that Ethiopians share with North African populations—display coalescent times in the early Holocene (table 3) a similar period to that estimated for North and East African Y chromosomes in haplogroup E3b1-M78, which is abundant and may have originated in Ethiopia (Cruciani et al. 2004; Luis et al. 2004). It is interesting that, like E3b1-M78, these mtDNA haplogroups are infrequent or absent in our Yemeni sample (table 1).
And
On the other hand, similar to mtDNA haplogroup (preHV)1, Y-chromosomal haplogroup J1-M267 can be identified as the sole branch that is highly abundant in the Near and Middle East and in northeastern and East Africa (Underhill et al. 2000; Semino et al. 2002, 2004; Luis et al. 2004). Higher STR diversity of this Y-chromosomal clade among Europeans and Ethiopians, as compared with populations from northeastern Africa and the Middle East, suggests that it may have reached Ethiopia(and Europe) early in the Holocene, whereas its frequent spread in North Africa and the Middle East may have been driven by the expansion of Arabs since the 7th century (Semino et al. 2004)..... Somewhat indirectly (inferred from figure 1 of Luis et al. 2004), J1-M267 chromosomes appear to be particularly frequent among southern Arabians (38% in Omanis) and well represented in Egypt (20%). Absence of the corresponding STR variation patterns for the Omani and Egyptian samples does not allow, at present,the inference of which, if either of the two, is likely to be closer to the Ethiopian J1-M267 chromosomes."
The author has me confused about Egypt, at first he says Ethiopian J lineages are of early Holocene derivation because STR diversity of this lineage distinguishes it from J1-M267 that pater spread into North Africa because of Arabs. Then the author says STR diversity doesn't indicate whether Ethiopian J1-M267 is closer to Egyptian or Omani J1-M267, but wouldn't Egyptian J1-M267 be indicative of the expansion of Arabs into North Africa? Anyways, moving on:
"The other two episodes of intrusion of Semitic influence, related to contacts with southern Arabia, are weakly supported by our data. This is because, among the haplogroup N lineages present in high frequency in the Tigrais and other Ethiopian ethnic groups, only a few revealed close relationships with equivalent lineages present in southern Arabia."
Which to me would seem to infer that West Eurasian N lineages in Ethiopia have nothing to do with Sabaeans, which begs the question as to what was the parental source population for those lineages. Any one have anything to comment on this?
Posts: 2595 | From: Vicksburg | Registered: Feb 2006
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posted
As we've gone through time and again, J lineages of "Neolithic" extraction in Ethiopians and certain other groups have been discerned from later J arrivals, when single-banded YCAIIa22-YCAIIb22 bearing Hg J chromosomes were taken into account and were found to be of very low incidence in the aforementioned groups when compared to many of the other groups with relatively more recent ancestry from "Southwest Asian" regions. The single-banded motif may have been introduced at certain points in time in the historical era.
quote:Originally posted by Mystery Solver: As we've gone through time and again, J lineages of "Neolithic" extraction in Ethiopians and certain other groups have been discerned from later J arrivals, when single-banded YCAIIa22-YCAIIb22 bearing Hg J chromosomes were taken into account and were found to be of very low incidence in the aforementioned groups when compared to many of the other groups with relatively more recent ancestry from "Southwest Asian" regions. The single-banded motif may have been introduced at certain points in time in the historical era.
I understand Supercar, but what about the mtDNA and the fact that Ethiopians and Southern Arabians share very little matching mtDNA haplotypes?
Posts: 2595 | From: Vicksburg | Registered: Feb 2006
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I understand Supercar, but what about the mtDNA and the fact that Ethiopians and Southern Arabians share very little matching mtDNA haplotypes?
If memory serves me correctly, I believe Richards et al. addressed this issue, but I'll get into it later. Got to go.
Posts: 1947 | Registered: Sep 2005
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posted
^ Wasn't this topic discussed before? -- That is findings that mtDNA haplogroups held in common between East African and North Africa are indigenous to Africans and that they correlated with Y-paternal E lineages??
Anybody got the links to that or those threads in the archives?
Posts: 26252 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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posted
Here's an excerpt of something I took note of about Richards et al.'s 2003 study some time back:
M1 presence could more likely be gene flow from East Africa into southwest Asia, as it is not found elsewhere in west Eurasia, nor the greater part of Asia for that matter. Nonetheless, it isn't difficult to notice the transparently cautious approach the authors decided to take with M1 [notwithstanding their earlier acknowlegement of the assignment of the origin of these lineages to Africa],...
...In the case of Ethiopia, the west Eurasian types mostly match types in Arabia, with only a couple of exceptions of rare derived types not found elsewhere. Haplogroups (pre-HV)1 and M1 are found primarily both in eastern Africa and Near East. In Ethiopia, in contrast to the other west Eurasian types, instances of both (pre-HV)1 and M1 types tended to be unique types or to match others found only in East Africa. These patterns - as well as the rather higher frequencies of (pre-HV)1 and M1 in Ethiopia - suggest that the (pre-HV)1 and M1 lineages in Ethiopia may be the result of fairly ancient interactions between East Africa and Eurasia, whereas the other west Eurasian types may the result of more recent historical gene flow...
Here's an excerpt of something I took note of about Richards et al.'s 2003 study some time back:
M1 presence could more likely be gene flow from East Africa into southwest Asia, as it is not found elsewhere in west Eurasia, nor the greater part of Asia for that matter. Nonetheless, it isn't difficult to notice the transparently cautious approach the authors decided to take with M1 [notwithstanding their earlier acknowlegement of the assignment of the origin of these lineages to Africa],...
...In the case of Ethiopia, the west Eurasian types mostly match types in Arabia, with only a couple of exceptions of rare derived types not found elsewhere. Haplogroups (pre-HV)1 and M1 are found primarily both in eastern Africa and Near East. In Ethiopia, in contrast to the other west Eurasian types, instances of both (pre-HV)1 and M1 types tended to be unique types or to match others found only in East Africa. These patterns - as well as the rather higher frequencies of (pre-HV)1 and M1 in Ethiopia - suggest that the (pre-HV)1 and M1 lineages in Ethiopia may be the result of fairly ancient interactions between East Africa and Eurasia, whereas the other west Eurasian types may the result of more recent historical gene flow...
L1-L3A make up 89% of mtDNAs in West Africa, > 90% in southern East Africa, ~70% in Somalia, and ~55% in Ethiopia.
The reason for the lower frequency of haplogroups L1-L3A in Ethiopia is the presence both of haplogroups (pre-HV)1 and M1 (at high frequencies) and of the west Eurasian haplogroups T, J, U, and HV, which are indicative of substantial gene flow from the Near East. West Eurasian mtDNAs are elsewhere very rare in sub-Saharan Africa, the main previously discovered examples having entered Nubia from Egypt (Krings et al. 1999) and into the western Sahara from northwest Africa (Rando et al. 1998).
In the case of Ethiopia, the west Eurasian types mostly match types in Arabia, with only a couple of exceptions of rare derived types not found elsewhere. Haplogroups (pre-HV)1 and M1 are found primarily both in eastern Africa and Near East. In Ethiopia, in contrast to the other west Eurasian types, instances of both (pre-HV)1 and M1 types tended to be unique types or to match others found only in East Africa. These patterns - as well as the rather higher frequencies of (pre-HV)1 and M1 in Ethiopia - suggest that the (pre-HV)1 and M1 lineages in Ethiopia may be the result of fairly ancient interactions between East Africa and Eurasia, whereas the other west Eurasian types may the result of more recent historical gene flow...
Our estimate of recent Near Eastern mtDNA input (22%) amounts to considerably more than the 5% of Passarino et al. (1998). Contra Passarino et al. (1998), this does not seem to differ from the recent Y-chromosome input from the Near East signaled by Y-chromosome haplography J, which they estimate at ~25% but which has been subsequently shown to vary substantially in deferent Ethiopian populations (Semino et al. 2002).
Haplogroups L1-L3A in the Near East reach their highest frequency in the Yemen Adamant (~35%). Other Arab populations - Palestinians, Jordanians, Syrians, Iraquis, and Bedouin - have ~10% - 15% of lineages of sub-Saharan African origin. These types are rarely shared between different Arab populations. By contrast, non-Arab Near Eastern populations - Turks, Kurds, Armenians, Azeris, and Georgians - have few or no sub-Saharan lineages, suggesting that gene flow from Africa has been specifically into Arab populations. For comparison
In their Hg compilations from various studies of the past, in addition to the present one, Richards et al. [2003] reckon that (pre-HV)1 lineages in the Ethiopian samples may very well also be more ancient “Near Eastern” arrivals, given the unique clades of the Ethiopian samples. Their compilations also show that frequencies for (pre-HV)1 are actually higher in Ethiopian samples than many of “Near Eastern” samples; the only close comparison from amongst the latter are the Bedouin samples of De Rienzo and Wilson‘s study (1991), which was shown at a frequency of 17% of that overall sample, and the Yemeni Jews of Richards et al. 2000 study and the Yemeni Jews of Thomas et al.’s 2002 study, where were shown at 26% and 17% respectively. The highest frequencies observed in Ethiopian samples of the (pre-HV)1 lineages, was that of Ethiopian Jews of Thomas et al.’s 2002 study. Now of course, pending further specifics about loci motif patterns, it is possible that (pre-HV)1 lineages spilled into Arabia at some points in time, even if the precursors for the Ethiopian examples came in from near East. As for such precursor’s coming from the near East, the justification used by the authors, is that much of the basal lineages appear in the “Near East” for this macro-Haplogroup. Who knows what the coding motifs and characteristic HVS sites actually are for the east African (pre-HV)1 examples vs. pre-HV lineages prevalent in the “Near East”? Again microscopic examination is warranted. The authors did seem to be compelled to concede to the African origins of M1 and of U6, and hence by definition, representing ancient gene flow from east Africa to the “Near East”. On the Y chromosome end, both E3a and E3b lineages in the “Near East” are noted, but with higher contribution from the latter derivative of the PN2 clade and perhaps representing more ancient arrivals than the former derivative. I suspect that E3b-M34 chromosomes are rarely factored into the east African contribution to the “Near Eastern” male gene pool, but that is indeed what it represents. They have a notable presence in the Arabian peninsula, if memory doesn’t betray me, and represent either “pre-Neolithic” or “Neolithic” East African contribution. The gist: there doesn’t appear to have been much “Historic” contribution from the Arabian peninsula, but those markers that may have been part of bidirectional gene flow between sub-Saharan East Africa and south Arabia, are generally those deemed to be of pre-historic - generally of “Neolithic” - extraction.
That's all for now; might add on, as I review old studies that I've might have overlooked, as well as any possible new ones that are brought to my attention.
Posts: 1947 | Registered: Sep 2005
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quote:Originally posted by Mystery Solver: [QUOTE]
Richards et al. -
Haplogroups L1-L3A in the Near East reach their highest frequency in the Yemen Adamant (~35%). Other Arab populations - Palestinians, Jordanians, Syrians, Iraquis, and Bedouin - have ~10% - 15% of lineages of sub-Saharan African origin. These types are rarely shared between different Arab populations. By contrast, non-Arab Near Eastern populations - Turks, Kurds, Armenians, Azeris, and Georgians - have few or no sub-Saharan lineages, suggesting that gene flow from Africa has been specifically into Arab populations.
Evergreen Writes:
The problem with the study by Richards is that he does not take into consideration the possibility that the distribution of Haplogroups L1-L3A in the "Near East" is correlated with the geographic spread of E3b around the Fertile Crescent.
Posts: 2007 | From: Washington State | Registered: Oct 2006
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posted
^Because Richards et al. are under the impression that these arrived more recently by the taking in of African females [in the Arab societies] during the historic periods for "gratification" purposes. They presumably base this on the discernable distribution pattern and frequencies between "Near Eastern" Jews and other non-Arab groups of the region vs. those in samples from Arab-speaking populations; from the differences therein, they attempt to extrapolate which lineages may be indicative of more ancient arrivals vs. relatively recent ones. But yes, these Euro researchers do generally seem hardwired when it comes to interpretations of typical African lineages of L1-L3, usually attributing them to the slave trade or the like. Of course, there have been indicators to the contrary.
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quote:Originally posted by Mystery Solver: [QUOTE]
Richards et al. -
Haplogroups L1-L3A in the Near East reach their highest frequency in the Yemen Adamant (~35%). Other Arab populations - Palestinians, Jordanians, Syrians, Iraquis, and Bedouin - have ~10% - 15% of lineages of sub-Saharan African origin. These types are rarely shared between different Arab populations. By contrast, non-Arab Near Eastern populations - Turks, Kurds, Armenians, Azeris, and Georgians - have few or no sub-Saharan lineages, suggesting that gene flow from Africa has been specifically into Arab populations.
Evergreen Writes:
The problem with the study by Richards is that he does not take into consideration the possibility that the distribution of Haplogroups L1-L3A in the "Near East" is correlated with the geographic spread of E3b around the Fertile Crescent.
Thats because they attribute it to the slave trade
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