Deluge of Atlantis

Deluge of Atlantis
Deluge of Atlantis

Friday, March 9, 2012

Eurogenes and the Post-Ice Age Recovery
[Reprinting the blog posting below, with my comments added at the end-DD]
Wednesday, March 7, 2012

[Atlantic] Northwest Eurasians + Southwest Eurasians + Mesolithic survivors = modern Europeans

For a long time, it was generally accepted that Europeans were direct descendants of Palaeolithic settlers of the continent, with some Middle Eastern ancestry in the Mediterranean regions, courtesy of Neolithic farmers. However, in the last few years, largely thanks to ancient DNA results, it dawned on most people that such a scenario was unrealistic. It now seems that Europe was populated after the Ice Age in a big way, by multiple waves of migrants from almost all directions, but especially from the southeast.

Getting to grips with the finer details of the peopling of Europe is going to be a difficult and painstaking process, and will require ancient DNA technology that probably isn’t even available at the moment. However, the mystery about the basic origins and genetic structure of Europeans was solved for me this week, after I completed a series of ADMIXTURE runs focusing on West Eurasia (see
K=10, K=11, K=12, K=13 and K=14). The map below, produced by one of my project members, surmises very nicely the most pertinent information from those runs (thanks FR7!). It shows the relative spread of three key genetic clusters, from the K=13, in a wide range of populations from Europe, North Africa, and West, Central and South Asia (i.e. the data represents the nature of West Eurasian alleles in the sampled groups, with only three clusters considered). The yellow is best described as Mediterranean or Southwest Eurasian, while the cyan and magenta, which are sister clades, and can be viewed as one cluster for the time being, as Northwest Eurasian.

Thus, it appears as if modern Europeans are made up of two major Neolithic groups, which are related, but at some point became distinct enough to leave persistent signals of that split. They spread into different parts of Western Asia before moving into Europe. The Southwest Eurasians, most likely from the southern Levant, dominated the Mediterranean basin, including North Africa and Southern Europe, and the Arabian Peninsula. I’m now convinced that Otzi the Iceman is the best know representative of the ancient Southwest Eurasians (see here and here). [Otzi the Iceman is indded related to the Southwest Eurasians, but out of the section that had been resident in the Balkans and Greece since the first colonization of Europe by modern man, the group associated with the mt DNA U haplogroups-DD]

The Northwest Eurasians possibly originated in the northern Levant, but that’s a pure guess. In fact, judging by the map above, their influence isn’t particularly strong in that part of the world today, and only becomes noticeable several hundred kilometers to the north and east, in the North Caucasus and Iran respectively. The northern Levant is actually dominated by a fourth West Eurasian cluster, tagged by me as "Caucasus" in the K=13 run, and not shown on the map above. I don't really know what to make of that one, but judging from the Fst (genetic) distances between all the clusters, it appears to be intermediate between the Southwest and Northwest Eurasians, although closer to the latter. So maybe it's a hybrid cluster?

In any case, the situation several thousand years ago might have been very different, and the origins of the Northwest Eurasians in the northern Levant would fit nicely with my theories about the
origins and spread of Y-chromosome haplogroups R1a and R1b. [Fitting the observations in with the R groups clarifies the statements a great deal, see my additional comments at the end-DD]

After their initial spread, it appears as if the Northwest Eurasians inhaled varying amounts of native Mesolithic groups in their newly acquired territories west, north and east of the Levant. This is being strongly suggested by the aforementioned ancient DNA results, at least as far as Europe is concerned. They also mixed heavily with Southwest Eurasians in Europe and nearby. That’s why, for instance, you’ll never find an Irishman who clusters closer genetically to an Indian than to other Europeans. However, even a basic analysis of their DNA, like my own ADMIXTURE runs, shows that a large subset of their genomes comes from the same, relatively recent, “Northwest Eurasian” source.

We can follow the same logic when talking about the differentiation between modern descendants of Southwest Eurasians. For instance, those in Iberia have significant admixture from Northwest Eurasians, while those in North Africa carry appreciable amounts of West and East African influence. [And the NW group, while another independant group out of the NE group by way of the  it all the way to West Africa, not shown on the chart but known from other similar genetic studies-DD]

I’m convinced that the scenario of the peopling of Europe outlined above, by two basic stocks of migrants from Neolithic West Asia, is the only plausible one, because the signals from the data are too strong to argue against it. I’m sure you’ll be seeing the same story told by scientists over the next few years in peer reviewed papers. They’ll probably come up with different monikers for the Southwest and Northwest Eurasians, but the general concepts will be the same.

However, that was the easy part. The hard part is linking the myriad of movements of these Southwest and Northwest Eurasians with archaeological and linguistic groups. Perhaps the earliest Southwest Eurasians into Europe were Afro-Asiatic speakers? To be honest, I have no idea, because that’s not an area I’ve studied closely. But I would say that it’s almost certain that the proto-Indo-Europeans were of Northwest Eurasian stock. It’s an obvious conclusion, due to the trivial to non-existent amounts of Southwest Eurasian influence in regions associated with the early Indo-Europeans, like Eastern Europe and Central Asia.

Perhaps the simplest and most diplomatic thing to do for the time being, would be to associate the entire Northwest Eurasian group with an early (Neolithic) spread of Indo-European languages from somewhere on the border between West Asia and Europe? I know that would work for a lot of people, specifically those who’d like to see an Indo-European urhemait in Asia, as opposed to Europe. But it wouldn’t work for me, especially not after taking a closer look at that map above.

As already mentioned, the Northwest Eurasians can be reliably split into two clusters, marked on the map in cyan and magenta. I call the cyan cluster North Atlantic, because it peaks in the Irish and other Atlantic fringe groups, and the magenta Baltic, because it shows the highest frequencies in Lithuanians and nearby populations. The story suggested by the map is pretty awesome, with the Baltic cluster seemingly exploding from somewhere in the middle of the Northwest Eurasian range, and pushing its close relatives to the peripheries of that range. Thus, under such a dramatic model, the North Atlantic is essentially the remnant of the pre-Baltic Northwest Eurasians, and appears to have found refuge in far Western and Northwestern Europe, in the valleys of the Caucasus Mountains, and in South Asia.

Indeed, there seems to be a correlation between the highest relative frequencies of the North Atlantic, and regions that are still home to non-Indo-European speakers, or were known to have been home to such groups in historic times. For instance, France has the Basques, while the British Isles had the Picts, who are hypothesized to be of non-Indo-European stock. Note also the native, non-Indo European speakers in the Caucasus, like the Chechens, who show extreme relative frequencies of the North Atlantic component. Moreover, at the south-eastern end of the Northwest Eurasian range, in India, there are still many groups of Dravidian speakers.

Below are two maps that isolate the relative frequencies of the North Atlantic (cyan) and Baltic (magenta) components, versus each other and the Southwest Eurasian cluster, to better show the hole in the distribution of the North Atlantic. To be sure, this North Atlantic can be broken down further, but only with more a comprehensive sampling strategy, especially of Northern and Western Europe.

That’s my take on what the data is showing, and other explanations are possible. But I don’t really know what they might be? I should also mention that the potentially proto-Indo-European Baltic cluster shows a remarkable correlation with the spread of Y-chromosome haplogroup R1a, and ancient DNA rich in this haplogroup from supposed early Indo-Europeans. I’ve blogged quite a bit about that over the years, so I’ll just post some links to those posts:

Best of 2008: Corded Ware DNA from Germany

Ancient Siberians carrying R1a1 had light eyes

Ancient Siberians carrying R1a1 had light eyes - take 2

Bronze Age Tarim Basin "Caucasoids" carried R1a1 (and European mtDNA lineages too)

Craniometric links between Central European Funnelbeaker folk and early Indo-European steppe tribes

Two ancient migration routes across Eurasia = two genetic clines on a modern MDS plot

By the way, does anyone know when we’ll finally get full genome sequences of a few corpses from Corded Ware, Yamnaya and Andronovo digs? I was hoping to see a lot more by now in terms of ancient DNA, than a couple of PCA plots showing old Otzi against a backdrop of limited reference samples. To top it all off, his genome isn’t even available to the public for further analysis, like the Palaeo-Eskimo was a while back

--Going on the R1 Y-DNA notices received and reprinted on this blog before, the story goes that: the original expansion is the group associated with India expanded Westward, where it eventually split into two subgroups, the ones which the author here calls the NW and NE populations. We lose track of the NW group for a few thousands of years while the NE group grows and expands up until the date associated with the end of the Ice Age, at which time the NW group suddenly and dramatically reappears along the Atlantic seaboard and pushes the NE population back. A trace of the NW group also filters in to NW Africa and is met by a similar trace of the African group up into Iberia, and that would be the Afroasiatic association (the yellow on the map) The "Caucasian" branch is where the Indo-Europeans had started BUT the languages were superimposed upon and adopted by the older NE and NW groups, the YDNA R1 groups, and the NE group actually has a better association with the Uralics, I should think. groups associated with the later Indoeuropean languages seem to fall into Centum and Satem halves, BUT once again, those two seem to now have separate and distinctive points of origin. AND it seems that the NW group is transAtlantic and is the same as thre R1 group which appears in North America; The suggestion was made (in the article quoted in the first posting to this string) that the NW European R1 group had been residing somewhere else associated with the North American population and then reappeared in Europe by a return immigration at the end of the Ice Age, which agrees with the scenario posted in the above article. So we also have two useful subgroups of the R1 YDNA in this breakdown: First the founder group Out Of India:

 And then the Atlantic group returning in the later Cromagnon waves along the Western Seaboave recently seen, with an association with Magdalenians and/or Megalithic cultures, and with the Celtic languages as it is also claimed :

--Also remembering that the Celtic languages used to be described as an older language with Afroasiatic (Hamitic) grammar over which an Indoeuropean vocabulary had been superimposed.

Best Wishes, Dale D.

No comments:

Post a Comment

This blog does NOT allow anonymous comments. All comments are moderated to filter out abusive and vulgar language and any posts indulging in abusive and insulting language shall be deleted without any further discussion.