Sunday, January 31, 2016

Some Horn African phenotypes: The Supposed Controversy

This is an odd controversy I've seen crop-up even extremely recently in the comment section of this video I posted months ago. The controversy seems to be what the West Eurasian ancestors of various modern Horn Africans looked like. Some even suggest they were dark-skinned and attempt to downplay just how similar they would have looked to modern West Eurasians.



The problem with the dark-skinned argument in particular is strewn out above. Somalis and other Horn Africans like the Beta Israel tend to have a frequency of about ~60% for the derived A allele of the SLC24A5 gene. You can check this through even your own raw genetic data by seeing if you're either "AA", "AG" or "GG" for the rs1426654 SNP (if you're AA or AG; you carry its derived rs1426654-A allele).


Why is this relevant? Well, it's because this gene is strongly associated with the pigmentation variation observed among modern South Asians, Europeans, West Asians and North Africans [1] and seems to have had a significant part in why individuals like the Algerian, Swedish and Pashtun man below are capable of being more de-pigmented than Africans like Dinkas or some South Asians like the Juang. [note]



It accounts for roughly 1/3 of the pigmentation difference between Europeans and "Africans", the latter of whom mostly don't have the derived allele but the ancestral "G" one (being "GG").

It also has a part in why we assume for now that Western European Hunter-Gatherers (a model of which is observable above with that blue eyed & brown-skinned man who's supposed to be La-Brana 1) were predominantly brown to dark skinned. It's because they, unlike modern Northern Europeans who are rich in WHG-related ancestry, and unlike Early European Farmers mostly from Anatolia; were mostly not derived for SLC24A5. [2]

They were seemingly "GG" or at times "AG" for the rs1426654 SNP (essentially so far lacking or having little of the rs1426654-A allele) whilst Early European Farmers who have their closest modern proxy in modern Europe being Sardinians- :


-were mostly "AA" much like most modern Europeans. It was they and the later expanding Steppe pastoralists who were seemingly carrying EHG and CHG related ancestry whom modern Europeans mostly owe their current de-pigmentation / "light skin" to.

There are of course other genes responsible for modern Europeans' pigmentation but the problem I am highlighting is that if some think the West Eurasian ancestors of Somalis and the earliest West Eurasian ancestors of Habeshas were essentially just like the Western European Hunter-Gatherers we've so far sampled in regards to skin-tone; they're already wrong as Somalis have an allele concerned with the development of light-skin that WHGs looked to, for now, mostly lack.

Again, the problem with the "dark-skinned West Eurasian ancestors" idea for Horn Africans' like Somalis' West Eurasian ancestors in this regard is rather simple... Many Somalis tend to be "AG" [4]  (such as myself) and some such as three of my own distant relatives can even be "AA" like Early European Farmers:



This suggests that our West Eurasian ancestors unlike some of the probably notably pigmented (darker-skinned) Western Hunter-Gatherers of Europe; would have been rather rich in regards to being "AA" with no doubt some "AG" individuals. Then there's modern Somalis and Habeshas' skin-tone variation that, while I dislike going into phenotypic traits, should be taken into account:




Somalis for example can vary between a near ink-black to an almost olive-ish skin-tone. The former or something somewhat lighter is more common back in Somalia itself (less common among the diaspora, I've found) where people spend more of their time outside basting in the sun but on average I'd say most people tend to be like those two women in the middle in the above image.

Though at the end of the day, all ridiculous biases and agendas aside, most will likely encounter someone in their own immediate and/or extended family within any of the above skin tone ranges (some maybe darker or lighter than the two extremes by a bit even). 

This to me suggests that Somalis are most likely the progeny, as their genomes somewhat suggest, of people who on the one end would possibly be as dark-skinned as modern Dinkas and people on the other end who would possibly be as light-skinned as some West Asians and North Africans like Peninsular Arabians.




The only real controversy here, in my humble opinion, is the one going on in people who think otherwise' heads because as I've noticed via experience; there seems to be some absurd "butt-hurt" reaction to clearly being, in some part, the phenotypic result of admixture which is nonsensical because most modern peoples' phenotypes only really developed within the last 5,000 to 25,000 years in some great part due to admixture.


East-Central Asians such as the Kazakhs above's phenotypes no doubt developed as a result of them being an inter-mixture between East Asian-related peoples and West Eurasians along with subsequent selection of course. 

Blonde or red-ish hair among some East-Central Asians? Most likely derived from their West Eurasian ancestors. Why do many East-Central Asians in terms of facial features tend to resemble various East Asians to some extent? Most likely due to their East Asian-related ancestors.



"ASI"s or frankly any component of South Asians' ancestry isn't truly well understood at this point as you can see here. We are in desperate need of ancient DNA from the region but ASI was thought by Reich and company to be related to the likes of the indigenous Andamanese or have contributed most strongly to South Indian groups such as the Paniya man and woman here

Regardless of ASI's validity as a full-blown component, Tamils' phenotypic traits are probably, in some part, to be the result of intermingling between peoples who looked at least vaguely similar to that Paniya man and woman, whom themselves have some notable West Eurasian ancestry, and peoples migrating into the subcontinent from West Eurasia among some contributions from other groups.



The two European politicians above (one Swedish and the other German) owe their phenotypes to selection and intermixing within the last 8,000 or so years. [2] Their phenotypes are the direct result of Western European Hunter-Gatherers, Early European Farmers and Pontic-Caspian Steppe Pastoralists intermixing.

Lighter eyes? Mostly owed to the indigenous Hunter-Gatherers of Europe. Light-skin? Looks to be mostly owed to the Anatolian Neolithic Farmers, Eastern European Hunter-Gatherers and Caucasus Hunter-Gatherer related peoples who contributed to modern Europeans' genesis.


Horn Africans like Somalis or the Tigrinya people above are likely no special exception. Our genomes clearly paint out a pre-historic inter-mingling between both "African" & "West Eurasian" peoples who would've been close to much of the ancestry in modern Dinkas in regards to the African side and much of the ancestry in Anatolian Neolithic Farmers or Bedouins (more so with the early farmers) in regards to the West Eurasian side.

So in line with this my opinion is simply: 

Looser curly hair among Horn Africans? Mostly Likely a result of nappy haired and straight to wavy haired people intermixing. No surprise; both nappy and straight to wavy hair can be found in modern Horn Africans. Horn Africans' skin-tones varying from ink-black to very light-brown? Most likely an intermingling between very dark-skinned and de-pigmented pre-historic peoples. And I highly doubt more ancient DNA will strongly contradict this.

A great many of the phenotypes you see today in the modern world are the result of intermixing between peoples who existed before these modern populations or even peoples who still exist in some cases, various modern Horn Africans are unlikely to be some sort of magical exception.

Horn of Africa

Although I must note something... Some people like in that video's comment section keep jumping on my saying that our West Eurasian ancestors would have looked at least similar to modern and even contemporary West Eurasians and think this means we don't truly have any inkling based on mere logic and current genomic evidence what they looked like.

This is false. What I mean when I always, as per usual, remain cautious and use the term "similar" is... We don't have ancient remains clearly representing our pre-historic ancestors on "either side"

We haven't sampled these hypothetical remains & we haven't tried reconstructing their facial features so of course we won't know exactly (down to the last hair follicle) how they looked until this is done but the notion because of this that they'd have magically looked obscenely distinct from modern and contemporary Eastern Africans (like Dinkas) & West Eurasians is a fantasy.

The only reason, in my humble opinion, this is a controversy to some is because again; there's something "insulting" or "troubling" to some people about their precious looks being the result of admixture in conjunction with selection.
Reference List:




4. Ethiopian Genetic Diversity Reveals Linguistic Stratification and Complex Influences on the Ethiopian Gene Pool, Pagani et al.

Notes:

1. The first image was made by a Wikipedia member and was based on data from the Yale School of Medicine's Allele Frequency Database.

2. I'm really not one for posts like this... I like to steer clear of discussing the development of phenotypic traits like pigmentation, hair texture, facial morphology and so on because discussing this kind of stuff eventually, when dealing with various groups, devolves into some retarded exchange about which non-European population is more "White" or "Black" or "Negroid" & "Caucasoid" (scientifically obsolete nonsense I tend to have a dislike for...) and seems to carry a lot of unnecessary emotional vitriol with it. However, this particular "issue" was getting slightly annoying and I was getting tired of repeating myself to some people on this matter so I made this post mostly to just link future encounters to.

3. Also, modern West Asians and North Africans like Egyptians do have the derived allele for SLC45A2's rs1891982 SNP as well (From what I know; this other gene is responsible for a decent part of what remains when dealing with the pigmentation difference between Europeans and "Africans").

Arabians seem to be 15-20% derived for that SLC45A2 SNP and about 100% derived for the SLC24A5 SNP. Horn Africans like Habeshas, Somalis and Beta Israels do not look to carry the derived allele for this SLC45A2 SNP though whilst Neolithic Europeans & Neolithic Western Anatolians carry it at somewhat low frequencies.

Recommended Reads:

The Genetic Architecture & Natural History of Pigmentation

20 comments:

  1. I can easily see the main "African" ancestors of Cushites and Ethio-Semites looking like this, very dark skin and low occurrence of prognathism:

    https://s-media-cache-ak0.pinimg.com/736x/d2/f8/31/d2f831517df7b44bd9cfaffd63976c49.jpg

    http://i5.xitek.cn/forum/pics/201207/1921/192190/192190_1341670962.jpg

    https://www.culturalsurvival.org/sites/default/files/styles/main_image_full_width/public/images/anuakwoman_1.jpg?itok=XPuvfP1v


    Mixing with very narrow-faced, Southwest Asian people who looked essentially like this (obviously less attractive on average):

    http://i25.tinypic.com/vpb5fp.jpg

    http://assets.nydailynews.com/polopoly_fs/1.1327758!/img/httpImage/image.jpg_gen/derivatives/article_970/handsome26n-1-web.jpg


    Ethiopians then have a layer of ancestry from peoples who looked like this (possibly basal(?) to their ancestry):

    http://www.interestingfacts.org/facts-images/hadza-people.jpg


    Plus a more recent intrusion of something like this, but possibly slighty lighter skinned:

    https://farm6.staticflickr.com/5287/5240250497_91725efc5e_z.jpg

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    1. Whoa there, amigo. This ain't ABF or something, no need for all those modern ethnic group picture shares. *evilgrin-emoticon* But yeah, my teasing aside, I think it's a bit messy to try and reconstruct deeper details without remains (stuff like the presence of "prognathism" for example) but we're on a similar boat in regards to the "two basal sides" of Horners' ancestors' physical features in a broader sense (in respect to skin-tone, hair texture, the vagaries of their facial morphology and so on), I suppose. Granted, I wouldn't be shocked if the Southwestern Arabian element in Habeshas somewhat resembled Yemenite Jews from a physical standpoint. We'll see someday with ancient DNA and such, I hope.

      Thanks for the comment, hombre. :)

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    2. I agree with pgbk87's assessment for the most part.

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  2. This is really interesting.As I'm myself AG and is generally very lightskinned(In Africa lol).In my immediate family I have dark skin,light skin and also mariin(dark reddish skintone).

    What I have noticed among horners is that the Habesha are much more lighter on average compared to Somali who can get as dark as the South Sudanese.Why is that?

    Also Somalis have a greater frequency in my opinion to have softer curly hair or straight hair(like my father who people think is tamil) then Habesha,Oromos and other Ethiopians other then Afars(who are similiar to us in hair form).Would this maybe explain the omotic influence in these groups? Is the omotic component the main reason even with elevated eurasian levels of 10% over us somalis they still have very "nappy" hair?

    Obviously I don't expect you to answer these questions with full scientifically backed answers but is just something I thought of when interacting with all the different horner groups I have personally met.I also wonder what the Afars would get in the rs1426654 SNP.

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    1. "What I have noticed among horners is that the Habesha are much more lighter on average compared to Somali who can get as dark as the South Sudanese. Why is that?"

      There are plenty of Habeshas (particularly in the Horn) who can be "as dark as the South Sudanese" or who are generally pretty heavily pigmented. You'll spot enough in this procession of sorts at Aksum:

      https://drive.google.com/folderview?id=0B2ARnUeK-Y8WNWpmRUhLM1JsZDQ&usp=sharing

      There's overall not a HUGE difference in skin-tone between the two groups and ultimately it depends on what "subsets" of them you're even comparing. If you compare Western diaspora Somalis (like in the UK) to Tigrinyas in Tigray; the Western diasporan Somalis are more de-pigmented on average in my humble opinion but of course there's a strong difference between Western diaspora Tigrinyas and Somalis in Northern Somalia (a rather arid region that gets a lot more Sun than somewhere like Sweden or the UK), where the former is notably less pigmented.

      If you compare the two western diaspora groups (peoples residing in the "same environment") then there is still a difference and the Habeshas can seem more de-pigmented on average. These are just my own observations. Why are things like that? To be fully honest: I don't know. Just plain Selection? Habeshas' later West Eurasian elements taking effect? Both? Again, these little details are messy and even a little silly to try and decode with our current data.

      "I also wonder what the Afars would get in the rs1426654 SNP."

      Keep in mind how the climate various Horn groups reside in can take its toll. Afars are by majority still pastoral nomads, a great many of whom live in the Danakil Desert (one of the world's most unforgiving deserts) & barely even have a diaspora so a good amount of their "natural pigmentation levels" are probably being skewed by this environment similar to how Western diaspora Somalis and Habeshas are noticeably less pigmented than their rural homeland counterparts in my experience.

      Anyway, let's end it here with comments of this sort where we try and "de-code" how certain Horn groups' differences came about. This is frankly one reason why I long hesitated about making this blog post.

      There are lots of problems with discussions like this... I.e. we're going off a person's own observations "I find this group to be lighter on average. Why is that?" it won't take long for discussions like this to devolve into "race-forum" type nonsense if other more "flamboyant" characters decide to interject with their opinions on how they think a group looks on average. I know that's not what you intended though but yeah... There's also the case of disagreements taking place... Someone might, by their experiences, not feel the same about a group's overall phenotype and then there's not even going to be a truly fruitful exchange. It's a silly and messy business. Even my own meanderings into the skin-tone differences between certain Horn groups suffer from being biased as they're based on my own experiences over the years.

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    2. I think what you see in Somalis and other Cushites like the Afar, is a founder effect followed by specific sexual selection. The "African" ancestors of Somalis were primarily tall and slender, had high rounded foreheads, likely had nappy hair and were Nilotic/Andamanese/Bouganville Islander level dark.

      The Amharas and Oromos have been integrating other groups (Cushitic, Omotic and even Nilotic speakers) into their own for a long time, so there is more room for variation.

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  3. I noticed that it is very easy to tell apart Eri-Ethiopian highlanders from ethnic Somalis. I can't pin it to one specific trait, but just the overall look.

    Which is quite interesting since there is a large overlap between the two (~80% similar ancestry).

    Meanwhile with Angolans vs Zulus, I have an extremely difficult time telling them apart. They too have roughly a ~80% ancestry overlap, but somehow do not look that differentiated.

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    1. It's probably due to the "later" elements in Habeshas and other Highlanders. The greater Omotic/Ethiopic-related influence & the later West Eurasian-related gene flows. These factors plus subsequent selection are probably responsible for the differences you and Drobbah and others have noticed.

      There is a solid amount of over-lap in looks apparent though. Some highlanders can look incredibly Somali and vice-versa. My own mother is very often taken for a "Habesha" rather than a Somali. Some Habeshas have a hard-time stomaching that she isn't "one of them". However I'd say Oromos in general, on average, always seemed to over-lap with Somalis more than Habeshas do but they're a pretty heterogeneous bunch, something we notice from a genetic perspective too. But even then I've personally always felt they over-lapped with us more. Just a personal observation.

      I know I said we should cease and desist with this sort of talk but you guys clearly aren't listening so... Fuck it.

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    2. Haha, I am sorry Awale. But thanks for your input.

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    3. Hehehe, it's fine, man. No worries. And you're welcome. ;-)

      But overall, I agree with you. You can generally tell the "overall" difference between Somalis and various Highlanders from a glance. A lot of over-lap is prevalent but overall; we look more SIMILAR than "the same" by far. In fact, I'd say this is the case between us and Afars too.

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  4. I have a question. In this quote:

    "It accounts for roughly 1/3 of the pigmentation difference between Europeans and "Africans","

    Why didn't you put Europeans in quotation marks?

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    1. I've explained in the past why I put "Africans" in quotation marks:

      https://drive.google.com/file/d/0B2ARnUeK-Y8WY0Ryb3QyQTIzS28/view?usp=sharing

      I don't do this with Europeans because Europe isn't exactly a very physically and genetically diverse region in comparison to Africa. There's nothing malicious going on if that's what you're trying to gauge.

      But thanks for the heads up, I'll add that link to the "Africans" part to prevent future confusion.

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  5. Kind of off topic but more of a comment to PGBK87..imo some horners actually look like a mixture of Nilotes and Southern Indians. :/ I always see these two features especially closer to Sudan or the North East corners of the Red Sea. I have been to Sudan and I thought the people looked somewhat Indian.

    Anyways...Awale, have you factored anything reg skin tone with more African mediated geneflow of Eurasian ancestry by way of Egypt?

    I would think the aboriginal inhabitants of of Egypt would be GG, even after early migrations of U6/M1 and possibly even later migrations if the change in skin color postdates Farming. I wonder what the data of Western Sudanese would be if we have it.

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    1. "Kind of off topic but more of a comment to PGBK87..imo some horners actually look like a mixture of Nilotes and Southern Indians. :/ I always see these two features especially closer to Sudan or the North East corners of the Red Sea. I have been to Sudan and I thought the people looked somewhat Indian."

      Sorry, old mate... I'd forgotten about your comment until now. I'd say we might, to some (not to me), resemble South Indians because we're somewhat similar-ish mixtures on a "physical level". Them being a crossing between whatever "Aboriginal South Asian" population (or populaitons) dominates much of the ancestry in groups like Paniyas and then seemingly CHG-related Near Eastern migrants and us being a crossing between a now "extinct" pre-historic Northeast African population quite similar to most of the ancestry in Southern Sudanese groups like Dinkas and migrants from the Near East represented somewhat by the modern "Southwest Asian" and "Mediterranean" clusters if we're focusing on the ancestry in Somalis.

      "Anyways...Awale, have you factored anything reg skin tone with more African mediated geneflow of Eurasian ancestry by way of Egypt?"

      No, I can't say I did.

      "I would think the aboriginal inhabitants of of Egypt would be GG, even after early migrations of U6/M1 and possibly even later migrations if the change in skin color postdates Farming. I wonder what the data of Western Sudanese would be if we have it."

      I guess I agree with you here. Very very early inhabitants of what is now Egypt before people from West Eurasia began seeping in were probably very pigmented and perhaps even similar to most of the "African" ancestry in modern Horn Africans like Somalis.

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  6. I felt it was more appropriate to post my question/discussion about this topic here. Does the AA,AG,GG gene express itself all the time? What I mean by this is, say I see a light skin Oromo, does this mean he is AA, or Ag, rather than GG? Can he be GG?

    The reason I ask this question is because couldn't it be possible for the west Eurasian ancestors in horners be both darker skinned (like many people in Socotra)and carry the AA allele without expressing it in their phenotype?

    I suppose however like you mentioned in your blog post that the wide display of skin color (as well as hair texture) in just 1 Somali or any other groups family could be evidence that they indeed would have been as light as MENA people today. I mean I've seen some Somalis and Eritreans who are pretty much as light as a darker "Arab" (excluding the very few arabians who are about as dark as a normal horner).

    Prior to you mentioning the alleles, I always assumed the west Eurasian ancestors were a dark skinned group, like many socotra people and that middle easterns sometime later developed lighter skinned.

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    1. "I felt it was more appropriate to post my question/discussion about this topic here. Does the AA,AG,GG gene express itself all the time? What I mean by this is, say I see a light skin Oromo, does this mean he is AA, or Ag, rather than GG? Can he be GG?"

      I suppose it can depend... One interesting correlation I've seen is that an Eritrean-Tigrinya friend is "GG" and is noticeably more pigmented/"darker" than the rest of his family and then his father, who's noticeably more de-pigmented, is "AG". Was an interesting case as we could both see rather exact correlation in the pigmentation difference between him and his own father. I don't suppose things will always be this exact however, two "AG" or even "AA" individuals don't entirely have to turn out to be the exact same skin-tone. Nearly all of the Somalis whose raw-genetic-data I have are "AG" but there is some variation between us (some are more de-pigmented than others etc.).

      At any rate, I suggest consulting Razib Khan's post on the genetics involved in all this, he does a good job:

      http://www.unz.com/gnxp/the-genetic-architecture-natural-history-of-pigmentation/

      "Prior to you mentioning the alleles, I always assumed the west Eurasian ancestors were a dark skinned group, like many socotra people and that middle easterns sometime later developed lighter skinned."

      Certain forms of de-pigmentation are relatively "new" developments, I'd say. What you see with modern Northern Europeans for example (requires more genes than just SLC24A5). But somewhat "light-skin" (what you see with various West Asians) doesn't seem THAT young, truth be told. It seems to have existed among the Caucasus Hunter-Gatherers and Anatolian Neolithic Farmers, if I'm not mistaken with the former. So that's a time frame of 7,000-13,000 years at minimum in West Asia.

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  7. where is this myth came from that Ethiopians are lighter than Somalis!! both have quite large light %percent,have seen Ethiopians both in the west and Ethiopia and this really not the case,, just my observation.

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  8. Hi Awale, your blog is interesting and a breath of fresh air. My name is James and I am an East African Bantu. It's interesting because you are an ethnic Somali researching and understanding the history and genome of your own people. I have come across so many blogs written by primarily European neo Nazis writing crap.

    What is your stance on the old colonial labels like Caucasian/Caucasoid in reference to you in the Horn?

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    1. "Hi Awale, your blog is interesting and a breath of fresh air. My name is James and I am an East African Bantu. It's interesting because you are an ethnic Somali researching and understanding the history and genome of your own people. I have come across so many blogs written by primarily European neo Nazis writing crap."

      Heh, thanks, man. Good to hear that and yeah... There're a lot of unpleasant people out there peddling pseudoscientific ways of interpreting Human genetic diversity and it's a shame.

      "What is your stance on the old colonial labels like Caucasian/Caucasoid in reference to you in the Horn?"

      Simply old-school pseudoscience focused around skull-and-facial morphology. They basically found that Somalis, Habeshas and the like were rather similar to West Eurasians in terms of cranio-form and then came up with these simplistic "sub-races" to explain all of Human diversity ("Negroid", "Caucasoid" etc. etc.). This stuff is pretty obsolete in modern biology and population genetics especially. Somalis and Habeshas are merely, on a basal level, a mixture between pre-historic Africans (who were likely quite similar to modern Southern Sudanese people) & Western Eurasians. Actual population genetics makes things a lot more complex than old-school anthropology implied.

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