Friday, December 26, 2014

Mediterranean and its connection to WHG admixture

It seems that just as Caucasus is somehow tied to the ANE admixture across the West Asia/ Middle East-> "Mediterranean" which tends to peak in Sardinians & Northwest Africans (Imazighen/ Berbers) is the product of a WHG influence on the basic "Near Eastern"/ "ENF" (Early Neolithic Farmer-> EEFs before their WHG admixture).

I somewhat suspected this based on Sardinians who before we knew about all these ancient genomes were consistently the peak of the "Southern European"/ Mediterranean component which also peaked in NW Africans [-] [-]. Sardinians trace over 80%~ of their ancestry to the EEFs (Neolithic group in Gamba et al.) and tend to overlap with them in plots from various studies [1] [2]:


They also pretty much lack ANE as Lazaridis notes and the author of Eurogenes (Davidski/ Polako) also confirms with his test that is pretty much as good at identifying ANE as Raghavan et al. If they show ANE-> it would be trace amounts of 1-2%~. They are by all accounts ENF + WHG with the following averages at Eurogenes K8:

65%~ ENF
35%~ WHG

 Surely, they as this component's peak should be representative of the mixture it represents? However I found this preposterous and never gave it much thought because it never dawned on me that NW Africans would have WHG/EF (European Forager) admixture.

However some updates to Eurogenes K=8 shows just that:

Moroccans: 16%~
Tunisians: 14%~
Mozabites: 14%~

Here is the spreadsheet & those are the WHG/ EF levels of NW Africans. The rest of their admixture is essentially ENF + Niger-Congo + AEA (Ancestral East African/ the standard East African/ Nilo-Saharan component).

The run's ability to identify WHG seems quite accurate and it finds the generally expected and usual levels (IIRCC) in Europe as per the studies. It also finds nearly 10%~ WHG/ EF admixture in its Turkish samples which are from Cappadocia and in the past such as in Paschou et al; Cappadocians demonstrated a clear pull towards Southern Europeans. [3] 

The levels of this component in the Levant are also consistent with data like how Arabized Levantines alongside Yahudim tend to plot with Jews like Ashkenazim whom Lazaridis et al. itself notes have EEF (WHG admixed) admixture (being 19%~ WHG on average) and they tend to pull more toward Southern Europeans of the Italic-Greek variety whilst other Jews who are fairly similar to them also pull that way, Cypriots as well in basically every other PCA plot (Principal Component Analysis) one may encounter them in also show this pull but pull towards those populations less than their Judaic counterparts do and sure enough- :

Cypriot: 11%~ WHG/ EF

- they are less WHG/ EF influenced than the Yahudim groups.

If one had to explain I would go with an explanation one chap gave me and I'll just quote him:

"As for how it came to be , well Berbers/NW Africans are resultings from Ibero-Maurisian hunter -gatherers (of ultimate Paleothic Eurasian ancestry long before the Neolithic) mixed with Early Neolithic Farmers (Basal Eurasian spread) and then mixed with Afro Asiatic speaking Pastoralists from Northeast Africa (roughly 5,000 years ago with the spread of Neolithic Pastoralism in Central Sahara)."

I'll honestly do more research and try to confirm this or place it under some kind of scrutiny as I'm not at all well-versed when it comes NW African ("Maghreb") pre-history. Although prior studies on NW Africans have found that there seems to be both influences from Europe & influences from the Near East present in NW Africa. [4] And as the writer of that paragraph notes there are some general observations when it comes to NW African genetics like the following:

"NW Africans are resultings from various Eurasian migrations , and the last one was the proto Berbers (AfroAsiatic pastoralists) from Northeast Africa who were a mix of East African and SW Asian. The oldest are the Ibero-Maurisian hunter gatherers , who were 20 000 years old (see Mechta Afalou type) with ultimate Eurasian ancestry (see the Taforalt MTDNA remains) , then you had also EARLY Neolithic Farming and the whole MTDNA H (H1 H5) dominance. Pre Afro-Asiatic NW Africans were most similar to Sardinians genetically , and considering we found very old E1A lineages in Sardinia , there must have been some contacts with North Africa. On a West Eurasian-centered PCA plot , NW Africans also cluster in between Sardinians and Egyptian/Bédouins. You do know that the main MTDNA lineages in the Maghreb (H , JT , U) show a discontinuity with Egyptians , meaning much of the maternal ancestry of Berbers didn't come from the Nile Valley (unlike their main YDNA)."

I may take the time at some point to make a post on NW African pre-history and possible more detailed explanations for their WHG/ EF admixture however for now I'd advise any parties reading to just focus on the fact that the data (them having such admixture) is there and make what you will of any other data and how this admixture came to be.

All things considered though... It seems clear that the "Mediterranean" component that used to come up in runs before we just began identifying the ENF, WHG/ EF & ANE admixture across West Eurasia (counting North Africa) is in the end; ENF + WHG/ EF

An unknown Hunter-Gatherer population extremely similar to European hunter-gatherers like Loschbour seem to have contributed to the populations of the Maghreb, the rest of their ancestry is essentially AEA + Niger-Congo (20-30%~) [4] [5] + the generic Middle Eastern component called "Near Eastern" in the author of Eurogenes' run, otherwise dubbed "ENF" (Early Neolithic Farmer) as it is surely what the farmers of Europe would have been like prior to acquiring WHG admixture like Stuttgart and the rest did. 

Maghrebis have no ANE though which fits with their lack of to near lack (very low levels, like with Peninsula Arabians) of Caucasus admixture. ANE also likely entered the Middle East/ West Asia via the Caucasus (where it peaks)  and it seemingly never went father than Northern West Asia (Caucasus, the Iranian Plateau, Anatolia, The Levant & Mesopotamia/ Iraq).

The Mediterranean populations ultimately look to be a mixture between WHG/ EF & ENF with an ANE influence in the Levant (Yahudim included), Anatolia & Southern Europe with this influence gone in Northwest Africa and only miniscule in Egypt. Maghrebis are ultimately also differentiated in terms of autosomal DNA via their heightened African admixture albeit Arabized Levantines have 5 to 15%~ African admixture [6] and Yahudim like Ashkenazim and the like also have a teensy negligible African influence.

And of course one must keep in mind the various distinct migrations that created these seemingly related populations which is visible i.e. in their Haplogroups (Y DNA & mtDNA markers); they're not exactly the exact same population spread out across the Mediterranean. 

In the end there looks to be just one Middle Eastern component which would be ENF (often represented by Southwest Asian/ Arabian?) which peaks in non-Levantine Bedouin, Saudis and the like who lack WHG/ EF & ANE influences. Mediterranean & Caucasus for now simply look ENF with WHG/ EF & ANE influences respectively.

The puzzle now is figuring out what ENF and its Basal Eurasian element are via ancient genomes from the Middle East & East Africa but I fear that maybe a long way off...

Reference List:

3.  Maritime route of colonization of Europe, Paschou et al.


We had a good discussion about ANE and its presence in the Near East along with tidbits of this post's subject matter at this thread.

Ultimately though... The only way we'll really know anything conclusive about the Middle East, the Caucasus & North Africa is by sampling ancient genomes in the area. Once we do that... Everything will be truly reliable. So I would also advise an air of skepticism whilst taking all this in.

Happy Holidays!

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