Sunday, May 29, 2016

Mehris are fully Eurasian?

Excerpt from an Abstract:

"Consistent with other studies, we found that North African and Near Eastern populations (including the Yemeni) generally have less Neanderthal ancestry than other western Eurasian populations. However, our ADMIXTURE results indicate that a subset of Yemeni samples from the Mahra governate share a very high level of ancestry (~85%) with a single Near Eastern component. Interestingly, these individuals have Neanderthal ancestry estimates that are greater than estimates from almost all Near Eastern and North African populations and are more consistent with estimates from European and South/Central Asian populations, suggesting that eastern Yemen may be an area of elevated Neanderthal introgression in the Near East. Greater sampling of Near Eastern populations is needed to better understand variation in Neanderthal ancestry and the site(s) where modern humans and Neanderthals interbred."

The subject matter of this study is Neanderthal ancestry, of course, but what's interesting to me is that they've noted a population from the Mahra Governorate of Yemen who, unlike other Arabians like the Yemenites farther westwards, have higher Neanderthal ancestry estimates that are closer to what one might expect from Europeans or South/Central Asians who are mostly of Out-of-Africa/Eurasian origins, lacking the noticeable Post-OoA African influences in various West Asian Arab and North African populations.


A Soqotri girl

In my opinion, they've basically come across the "Mehri people" who, along with the likes of Soqotris like the girl in the picture above, have long interested some folks such as myself because of their phenotypic traits. They essentially look rather "Arabian" in regards to most of their traits but are, interestingly, very pigmented (dark-skinned) in many but not all cases. Arabic is also not their first language, they instead speak the "Modern South Arabian" languages which people should not confuse as being descendants of the "Old South Arabian" languages (i.e. Sabaean) or the likes of Himyaritic.

I've encountered people over the years who've fervently asserted that the pigmentation these peoples display is mostly owed to African admixture whilst using the seemingly, make what you will about his other ideas, very real Cushitic substratum in their languages discovered by Militarev [2] as an indicator that this might be the case. Yet, so far we've only gotten uniparental data on Soqotris which didn't imply that were very African influenced  [3] and now we might just have some Mehri autosomal DNA on our hands which is also not proving consistent with African admixture.

Supposedly a Mehri man

Nevertheless, I've personally just looked upon them as looking like highly pigmented Arabians. Upon looking at their facial features, save for those who have recent outside admixture from Southeast African Bantu speaking people or Yemenite Arabs, I always got the impression that these folks looked quite similar to other Arabians like the Rashaida, they were just more pigmented on average and it seems my instincts may have been correct if these Mahra governorate samples are them.

Why are they this pigmented, then? Well, read this older post (as well as some links it shares) to get some of the dynamics behind pigmentation and you might get what's causing their pigmentation to be the way it is. Though, not all of them are as pigmented as the man or girl above, mind you. The two of them are meant to be "extreme examples" I've chosen for dramatic effect. These folks, nevertheless, have seemingly been isolated from the rest of the Arabian Peninsula for quite a long time (from a genetic perspective) so that likely has something to do with their looks as well.

I reached out to one of the authors of the forthcoming study but the thing is; it's still a forthcoming study/paper (all that's available right now is the abstract) and they've opted out of making the samples available to me or anyone else until the study's been published so we'll have to wait before we can fiddle with these new samples and really learn some mind-blowing stuff.

Reference List:

1. Neanderthal ancestry in Yemeni populations, Vyas et al.

2. Afro-Asiatic Migrations: Linguistic Evidence

3. Out of Arabia—The settlement of Island Soqotra as revealed by mitochondrial and Y chromosome genetic diversity, Černý et al.

12 comments:

  1. Finally another blog lol, good to have you back, tho it looks like you're back earlier than me with your prior blog posts.

    These people have got to be the most interesting west eurasians for me. To be honest with you, I agree with you about their phenotype. They look more like what people ascribed horners to (and still do to some extant), a darker version of Arabians.

    To the second last paragraph. Are you perhaps suggesting that it's a possibility that some of them do not posses the skin allele associated with west Eurasian light skin?

    I personally would guess with my limited knowledge that they split of from an ancestral parent group that they shared arabians with and got isolated, preserving some traits that were perhaps lost in Arabians.
    It would be funny if some of them turned out to be as "non African" as say Assyrians. Though there does appear to be south eastern African populations there.

    Another great blog, thanks for sharing.

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    1. Thanks for the warm welcome. :-)

      I used to find them real interesting too (still somewhat do) and once did wonder if the West Eurasian predecessors of "Horners" like Somalis were of their sort but I've increasingly come to doubt it for various reasons including the whole pigmentation issue. And yeah, I was implying that they might, to some great extent, only have the ancestral variants of those alleles the way various African populations do and this may have been caused by them splitting off from other West Eurasians real early which is staggering, to be quite frank. The idea that an "isolate" set of populations this small in number have lasted long enough to mostly avoid such gene flow is quite surprising.

      And yes, particularly around Socotra, some later SE African folk were brought over via the slave trade, if I recall correctly. So these guys may have at least some "African" input, to be fair. Those Soqotris tested for their uniparentals were ~10% Y-DNA E (rest was an overload on Y-DNA J). I have a weird feeling SOME of their Y-DNA E will turn out to be E-V32 or some other Cushitic speaker associated E-M78 lineage (to fit with this Cushitic substrate in their languages):

      "Although the subtypes of haplogroup E were not finely resolved in our analysis, thetotal contribution of E haplotypes to the Soqotra genepool is not greater than 9.5%."

      But, nevertheless, some or all of it may very well be lineages associated with Bantu speakers, if not all of it. Also... Yeah, it'll be quite funny if they turn out to be as "Non-African" as groups like Assyrians. If these samples are seriously them (most likely are); then these Neanderthal levels certainly make it sound like they're pretty close to being that "Non-African".

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    2. Np man and great response.

      I think it's a common assumption to assume the west eurasian ancestry in horners were like these people because our skin tone on average is more in line with the ssa average than the mena average, But if you look at the closest proxies to our ancestors, you'll notice actually we're pretty intermediate between them.

      E-V32 aye? I would agree if they have a cushitic substream (which I did not know btw, I only thought the ethio-semitic languages had them due to the obvious cushitic influence and they actually being for the most part language shifters).

      Yes indeed. At the very least I expect them to be much less african than north Africans.

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    3. "But if you look at the closest proxies to our ancestors, you'll notice actually we're pretty intermediate between them."

      Good of you to catch that, yeah. I.e. our "African" side is closest to South Sudanese people like Dinkas and our West Eurasian side is closest, if we're talking modern populations, to peoples like Negevite Bedouins. Not exactly Yorubas and Northern Europeans we're talking about here in terms of pigmentation (both Yorubas and Northern Europeans are more de-pigmented, on average, than Dinkas and Negevite Bedouins respectively).

      "E-V32 aye? I would agree if they have a cushitic substream (which I did not know btw, I only thought the ethio-semitic languages had them due to the obvious cushitic influence and they actually being for the most part language shifters)."

      That or any other E-M35 subclade associated with Cushitic speaking Afro-Asiatic speakers. E-V22, E-V6 etc. But we'll see, I guess. :-)


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  2. Hey Awale! Another great post! Very fascinating as we know very little regarding the Mehri, Soqotris and other South Arabians genetically compared to other groups in this region.

    Hmm regarding the hypothesis that Mehris might be fully Eurasian, is this due to their higher Neanderthal levels?

    This would means that the higher African ancestry, the lower the Neanderthal levels will be? This might be correct as most African populations have none to very negligible amounts of Neanderthal admixture (Yoruba from what I heard in anthrogenica has 0.3% Neanderthal) from what I read. :P

    I also think that Soqotris and probably Mehris have some African ancestry from SE Africans like what Jason and you mentioned. :)

    Off topic, the Soqotri girl looks very South Indian or Sri Lankan to me. I also saw other pictures of kids from Soqotra and they look very South Indian to me. But this likely has to do with climate and geography than genetics IMHO.

    This is me, Khuur from anthrogenica btw (just under another different username)!

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    1. Welcome Khuur, ya Khuur. :-)

      Yes, I'm assuming they might be fully, or close to fully, Eurasian because of their high Neanderthal levels which the abstract claims is comparable to the levels in Europeans and South/Central Asians who don't have any or much at all "African" admixture.

      African groups that seemingly lack, or mostly lack, Out-of-Africa/Eurasian admixture have extremely little to no Neanderthal admixture. There have indeed been signs of such admixture in groups like Yorubas (something I've alluded to on this blog before) but those are still minuscule hints so the basic idea is that "African" admixture does dilute one's Neanderthal ancestry levels if they're descended from a group like the Han or from Poles ("full-on Eurasians"). If I were fully Polish, I'd mostly likely have more Neanderthal ancestry than someone who's 60% Yoruba & 40% Polish, for example. So you've understood my point there, yeah. Various other Afro-Asiatic speaking groups in West Asia and North Africa have lowered Neanderthal levels because of their "African" admixture (hence why I linked to that old post about that very admixture in them).

      And yeah, you maybe right about them having at least SOME SE African input as Jason and I suggest.

      "Off topic, the Soqotri girl looks very South Indian or Sri Lankan to me. I also saw other pictures of kids from Soqotra and they look very South Indian to me. But this likely has to do with climate and geography than genetics IMHO."

      Hehehe, you know this actually, quite strangely, fits with what some more "old-school racialist anthropologists" thought of these guys? Guess what these folk used to be "classified" as (or at least Arabians who resembled this sort of look).

      https://books.google.ae/books?id=n9kJ7EZ8LJsC&pg=PA203&lpg=PA203&dq=South+Arabian+Veddoids&source=bl&ots=jF4or9j2Rs&sig=diOxcR0-EY-rqUxj_5umGlKZIWU&hl=en&sa=X&ved=0ahUKEwiC4Z6Uxo7NAhUkCsAKHdh2CZoQ6AEIJzAC#v=onepage&q=South%20Arabian%20Veddoids&f=false

      "Veddoid South Arabians"

      So you're not the first to bring up some odd comparison to South Indians or South Asians in general. But these Modern South Arabian speaking chaps are, in my humble opinion, some sort of "basal" ENF/Southwest Asian type population for the most part while South Indians like Tamils are seemingly more of a mix of CHG-like ancestry and whatever non-West Eurasian Andamanese-Australo-Melanesian-LIKE element exists in groups like Paniyas. So the similarities are only VAGUELY phenotypic.

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    2. Thanks for your welcome Sheikh! :D

      Would you say most West, Central,Southern Africans lack any Eurasian admixture?

      Also do some East Africans like Nilotic Dinka, Nuer, Shilluk and other Nilo-Saharan lack any Eurasian?

      Yep the similarities are only phenotypic.

      I agree with you that these modern South Arabians are likely mostly ENF/Southwest Asian+ some minor African (in the case of Soqotris, Mehris)

      I think the vague phentoypic similarity has to do with adaptation to the hot sunny climate of both South India and Southern Arabian peninsula.

      Hmm, yes it seems my opinion resembles some of the racialist anthropologists. :P


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    3. No prob about the welcome, ya Khuur. :-)

      As for whether or not West-Central Africans TOTALLY lack "Eurasian" input... I wouldn't say there's a total lack of such ancestry. There's the case of mtDNA U6 which can be rather common in Western Africa and then there's Y-DNA R1b-V88 which is tied to Chadic speakers and is, if I'm not mistaken, quite common among Chadic speakers like Hausas. Then there is the case of that minuscule hint of Neanderthal ancestry (~0.3%) in quintessentially West-Central African populations like Yorubas. Now, some in the Genomics-Forumer world tend to suggest that this MIGHT not be "real" Neanderthal ancestry owed to Eurasian admixture and we might be picking up on hints of "archaic" admixture in some African populations that's more local to Africa itself rather than being Denisovan or Neanderthal admixture like with Eurasians but only further study and ancient DNA might tell us definitively what the truth is in this case. Then, from time to time, you do notice that certain groups have minor-to-negligible Northwest African-related admixture. It can be substantial for some such as various Fulanis:

      http://anthromadness.blogspot.ae/2015/07/revisiting-dobon-et-al-2015-fulani.html

      So I wouldn't say Western Africa in particular is a complete dead-zone for "Eurasian" ancestry but most groups would certainly have very low to negligible amounts of such ancestry, if any at all is present.

      "Also do some East Africans like Nilotic Dinka, Nuer, Shilluk and other Nilo-Saharan lack any Eurasian?"

      There can be some but it's negligible overall. Some of these groups can show minor hints via uniparental data:

      http://ethiohelix.blogspot.ae/2013/02/sudan-ydna.html
      http://ethiohelix.blogspot.ae/2015/06/sudan-mtdna.html
      http://ethiohelix.blogspot.ae/2013/01/east-african-mtdna-variation-has.html
      http://ethiohelix.blogspot.ae/2012/11/extensive-doctoral-thesis-on-ethiopian.html

      But, overall, the only real hints of "Eurasian" input, if we're talking autosomal DNA, in them can pop-up at the Lower-Ks of some ADMIXTURE runs where you'll see very tiny (1-3%) hints of something broadly OoA/Eurasian in them but it doesn't look to be West Eurasian in particular but just something more broadly Eurasian. Other than that, they honestly don't show much Eurasian, especially West Eurasian, admixture except for the odd carrier of Y-DNA markers like J1 or mtDNA markers like HV and maybe negligible (1-5%) levels in the odd person here and there when looking at their autosomal DNA. I'm, of course, excluding people who might be more recently mixed...

      "I think the vague phentoypic similarity has to do with adaptation to the hot sunny climate of both South India and Southern Arabian peninsula."

      Perhaps, yeah. I've never given the climatic drivers too much thought myself but you maybe right.

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    4. "There's the case of mtDNA U6 which can be rather common in Western Africa and then there's Y-DNA R1b-V88 which is tied to Chadic speakers and is, if I'm not mistaken, quite common among Chadic speakers like Hausas. Then there is the case of that minuscule hint of Neanderthal ancestry (~0.3%) in quintessentially West-Central African populations like Yorubas. Now, some in the Genomics-Forumer world tend to suggest that this MIGHT not be "real" Neanderthal ancestry owed to Eurasian admixture and we might be picking up on hints of "archaic" admixture in some African populations that's more local to Africa itself rather than being Denisovan or Neanderthal admixture like with Eurasians but only further study and ancient DNA might tell us definitively what the truth is in this case."

      "So I wouldn't say Western Africa in particular is a complete dead-zone for "Eurasian" ancestry but most groups would certainly have very low to negligible amounts of such ancestry, if any at all is present"

      Hmm I see so to the only way to know if any at all Eurasian input is present in West-Central Africa and whether the tiny negligible Neanderthal input in Yoruba is some type of archaic African admx or actual Neanderthal, is that there need to be further study and more ancient DNA genomes to tell the definite truth?

      "But, overall, the only real hints of "Eurasian" input, if we're talking autosomal DNA, in them can pop-up at the Lower-Ks of some ADMIXTURE runs where you'll see very tiny (1-3%) hints of something broadly OoA/Eurasian in them but it doesn't look to be West Eurasian in particular but just something more broadly Eurasian."

      Do you know what is this type of broadly Eurasian component? What modern population does this broadly Eurasian peaks in? So we can say it is likely that Nuer, Dinka and other East African Niotics have slightly more Eurasian (although still in extremely small negligible amounts) than West-Central Africans?

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    5. "Hmm I see so to the only way to know if any at all Eurasian input is present in West-Central Africa and whether the tiny negligible Neanderthal input in Yoruba is some type of archaic African admx or actual Neanderthal, is that there need to be further study and more ancient DNA genomes to tell the definite truth?"

      Pretty much.

      "Hmm I see so to the only way to know if any at all Eurasian input is present in West-Central Africa and whether the tiny negligible Neanderthal input in Yoruba is some type of archaic African admx or actual Neanderthal, is that there need to be further study and more ancient DNA genomes to tell the definite truth?"

      It seems more Eastern Non-African (ENA) or East Asian-like than West Eurasian, from what I recall, which could just imply that this is some old affinity for Eurasians showing in these populations (given that they're East Africans) OR they may have some pretty old Eurasian admixture that could, oddly, resemble ENAs more than West Eurasians. Honestly, can't be sure. It's really odd. It might not even be entirely real, truth be told. Just some "noise" that turns up at K=2 or K=3 and could be more indicative of an affinity more than anything else.

      As for whether or not they have more "Eurasian" ancestry than West-Central Africans... It really depends on the populations within these macro-populations. A Dinka would obviously have less than many Fulanis. A Yoruba would likely have less than a Gumuz. Can't quite generalize, in my humble opinion.

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