Razib Khan One-stop-shopping for all of my content

October 22, 2018

The phylogenetic trees falling on the tundra

Filed under: Historical Population Genetics,Population genetics,Siberia — Razib Khan @ 9:59 pm


A massive new ancient DNA preprint just dropped, The population history of northeastern Siberia since the Pleistocene:

…Here, we report 34 ancient genome sequences, including two from fragmented milk teeth found at the ~31.6 thousand-year-old (kya) Yana RHS site, the earliest and northernmost Pleistocene human remains found. These genomes reveal complex patterns of past population admixture and replacement events throughout northeastern Siberia, with evidence for at least three large-scale human migrations into the region. The first inhabitants, a previously unknown population of “Ancient North Siberians” (ANS), represented by Yana RHS, diverged ~38 kya from Western Eurasians, soon after the latter split from East Asians. Between 20 and 11 kya, the ANS population was largely replaced by peoples with ancestry from East Asia, giving rise to ancestral Native Americans and “Ancient Paleosiberians” (AP), represented by a 9.8 kya skeleton from Kolyma River. AP are closely related to the Siberian ancestors of Native Americans, and ancestral to contemporary communities such as Koryaks and Itelmen. Paleoclimatic modelling shows evidence for a refuge during the last glacial maximum (LGM) in southeastern Beringia, suggesting Beringia as a possible location for the admixture forming both ancestral Native Americans and AP. Between 11 and 4 kya, AP were in turn largely replaced by another group of peoples with ancestry from East Asia, the “Neosiberians” from which many contemporary Siberians derive. We detect additional gene flow events in both directions across the Bering Strait during this time, influencing the genetic composition of Inuit, as well as Na Dene-speaking Northern Native Americans, whose Siberian-related ancestry components is closely related to AP. Our analyses reveal that the population history of northeastern Siberia was highly dynamic, starting in the Late Pleistocene and continuing well into the Late Holocene. The pattern observed in northeastern Siberia, with earlier, once widespread populations being replaced by distinct peoples, seems to have taken place across northern Eurasia, as far west as Scandinavia.

The preprint is very interesting and thorough, and the supplements are well over 100 pages. I read the genetics and linguistics portions. They make for some deep reading, and I really regret making fun of Iosif Lazaridis’ fondness for acronyms now.

I will make some cursory and general observations. First, the authors got really high coverage (so high quality) genomes from the Yana RS site. Notice that they’re doing more data-intense analytic methods. Second, they did not find any population with the affinities to Australo-Melanesian that several research groups have found among some Amazonians. Likely they are hiding somewhere…but the ancient DNA sampling is getting pretty good. We’re missing something. Third, I am not sure what to think about the very rapid bifurcation of lineages we’re seeing around ~40,000 years ago.

The ANS population, ancestral by and large to ANE, seems to be about ~75% West Eurasian (without much Basal Eurasian) and ~25% East Eurasian. Or at least that’s one model. Did they then absorb other peoples? Or, was there an ancient population structure in the primal ur-human horde pushing out of the Near East? That is, are the “West Eurasians” and “East Eurasians” simply the descendants of original human tribes venturing out of Africa ~50,000 years ago? Also, rather than discrete West Eurasian and East Eurasian components, perhaps there was a genetic cline where the proto-ANS occupied a position closer to the former, as opposed to some later pulse admixture?

Without more ancient DNA we probably won’t be able to resolve the various alternative models.

October 3, 2018

Nomads, cosmopolitan predators, and peasants, xenophobic producers

Ten years ago when I read Peter Heather’s Empires and Barbarians, its thesis that the migrations and conquests of the post-Roman period were at least in part folk wanderings, where men, women, and children swarmed into the collapsing Empire en masse, was somewhat edgy. Today Heather’s model has to a large extent been validated. The recent paper on the Lombard migration, the discovery that the Lombards were indeed by and large genetically coherent as a transplanted German tribe in Pannonia and later northern Italy, confirms the older views which Heather attempted to resurrect. Additionally, the Lombards also seem to have been defined by a dominant group of elite male lineages.

Why is this even surprising? Because to a great extent, the ethnic and tribal character of the post-Roman power transfer between Late Antique elites and the newcomers was diminished and dismissed for decades. I can still remember the moment in 2010 when I was browsing books on Late Antiquity at Foyles in London and opened a page on a monograph devoted to the society of the Vandal kingdom in North Africa. The author explained that though the Vandals were defined by a particular set of cultural codes and mores, they were to a great extent an ad hoc group of mercenaries and refugees, whose ethnic identity emerged de novo on the post-Roman landscape.

In the next few years, we will probably get Vandal DNA from North Africa. I predict that they will be notably German (though with admixture, especially as time progresses). Additionally, I predict most of the males will be haplogroup R1b or I1. But the Vandal kingdom was actually one where there was a secondary group of barbarians: the Alans. It was Regnum Vandalorum et Alanorum. I predict that Alan males will be R1a. In particular, R1a1a-z93.

But this post is not about the post-Roman world. Rather, it’s about the Inner Asian forest steppe. The sea of grass, stretching from the Altai to the Carpathians. A new paper in Science adds more samples to the story of the Sbruna, Cimmerians, Scythians, and Sarmatians. Ancient genomes suggest the eastern Pontic-Caspian steppe as the source of western Iron Age nomads. The abstract is weirdly nonspecific, though accurate:

For millennia, the Pontic-Caspian steppe was a connector between the Eurasian steppe and Europe. In this scene, multidirectional and sequential movements of different populations may have occurred, including those of the Eurasian steppe nomads. We sequenced 35 genomes (low to medium coverage) of Bronze Age individuals (Srubnaya-Alakulskaya) and Iron Age nomads (Cimmerians, Scythians, and Sarmatians) that represent four distinct cultural entities corresponding to the chronological sequence of cultural complexes in the region. Our results suggest that, despite genetic links among these peoples, no group can be considered a direct ancestor of the subsequent group. The nomadic populations were heterogeneous and carried genetic affinities with populations from several other regions including the Far East and the southern Urals. We found evidence of a stable shared genetic signature, making the eastern Pontic-Caspian steppe a likely source of western nomadic groups.

The German groups which invaded the Western Roman Empire were agropastoralists. That is, they were slash and burn farmers who raised livestock. Though they were mobile, they were not nomads of the open steppe. Man for man the Germans of Late Antiquity had more skills applicable to the military life than the Roman peasant. This explains in part their representation in the Roman armed forces in large numbers starting in the 3rd century. But the people of the steppe, pure nomads, were even more fearsome. Ask the Goths about the Huns.

Whole German tribes, like the Cimbri, might coordinate for a singular migration for new territory, but for the exclusive pastoralist, their whole existence was migration. Groups such as the Goths and Vandals might settle down, and become primary producers again, but pure pastoralists probably required some natural level of predation and extortion upon settled peoples to obtain a lifestyle beyond marginal subsistence. Which is to say that some of the characterizations of Late Antique barbarians as ad hoc configurations might apply more to steppe hordes.

There has been enough work on these populations over the past few years to admit that various groups have different genetic characteristics, indicative of a somewhat delimited breeding population. But, invariably there are outliers here and there, and indications of periodic reversals of migration and interactions with populations from other parts of Eurasia.

Earlier I noted that Heather seems to have been correct that the barbarian invasions of the Roman Empire were events that involved the migration of women and children, as well as men. The steppe was probably a bit different. Here are the Y and mtDNA results for males from these data that are new to this paper:

Culture MtDNA Haplogroup Y Haplogroup
Late Sarmatian U5b2b R1b1a1a2?
Scythian U5a2a1 R1b1a1a2?
Late Sarmatian D4q R1b1a1a2
Scythian J2b1a6 R1b1a1a2
Scythian U5a1a1 R1b1a1a2
Scythian U5b2a3 R1b1a1a2
Scythian U4* R1b1a1a2
Scythian U5a2b R1b1a1a2
Cimmerian H9a R1b1a
Srubno-alakulskaya T2a1 R1a1a1?
Srubno-alakulskaya J1c3a R1a1a1
Srubno-alakulskaya H R1a1a1
Srubno-alakulskaya HV0a R1a1a1
Srubno-alakulskaya U5a1 R1a1a1
Srubno-alakulskaya HV0a R1a1a1
Late Sarmatian T1a1 R1a1a
Cimmerian C5c (50%) Q1a1

I’m assuming you aren’t surprised. These steppe tribes seem to be defined by extended paternal lineage networks. The Sbruna people are R1a1a1, as is dominant in Eastern Europe today. But, an ancient Sbruna male dating to 1800 BC was found to have the Asian variant of R1a1a1, found in South and Central Asia, not the one predominant among Slavic peoples.

Click to enlarge

Speaking of South Asians, there is some interesting discussion on this issue in the paper. I’ll quote a few sections:

The Bronze Age Srubnaya-Alakulskaya individuals from Kazburun 1/Muradym 8 presented genetic similarities to the previously published Srubnaya individuals. However, in f4 statistics, they shared more drift with representatives of the Andronovo and Afanasievo populations compared to the published Srubnaya individuals. Those apparently West Eurasian people lacked significant Siberian components (NEA and SEA) in ADMIXTURE analyses but carried traces of the SA component that could represent an earlier connection to ancient Bactria. The presence of an SA component (as well as finding of metals imported from Tien Shan Mountains in Muradym 8) could therefore reflect a connection to the complex networks of the nomadic transmigration patterns characteristic of seasonal steppe population movements….

There are two ways, not exclusive, that I can explain the “South Asian” component you find in some of the steppe individuals. First, the “South Asian” component is found in the Neolithic Iranian sample. And, you can see in another plot that the Scythians are enriched for West Asian ancestry in comparison to the Sbruna. As noted above there was probably south to north migration of these Indo-European nomadic groups. So yes, just as with the East Asia ancestry which periodically appears, this is evidence of an “Inner Asian International.”

A second possibility though is that the South Asian ancestry is artifactual and that it’s just emerging in ADMIXTURE because of shared ancestry between the Sbruna and South Asians because of gene flow from the steppe into South Asia (and since South Asians have “Iranian farmer” ancestry it also pops up in the Iranian Neolithich sample).

The Sbruna flourished between the 18th and 12th centuries BC. According to Wikipedia:

Philological and linguistic evidence indicates that the bulk of the Rigveda Samhita was composed in the northwestern region of the Indian subcontinent, most likely between c. 1500 and 1200 BC.

Mitannia Indo-Aryan is attested in Syria in 1380 BC.

In the centuries around 1500 BC it seems quite possible that there was a “Indo-Aryan Inner Asian International”, just as in the first millennium AD there emerged a Turkic International, and for more than a century after 1200 AD there was a Mongol International. In the north, the Indo-Aryans were absorbed by Iranian and Uralic peoples. In West Asia they didn’t have a major cultural impact, aside from introducing chariots. It is in India by happenstance that Indo-Aryan linguistic culture and aspects of their folk memory is preserved to this day.

This isn’t that amazing. Half of the speakers of Turkic langauges are ethnic Turks, who live in Turkey. Anatolia genetically isn’t really very East Asian, though there is some of that. But the cultural heritage of the ancient Turks remains stronger there than in areas anciently inhabited by Turks, such as western Mongolia (where the people are genetically more like the original Turks were in the first millennium AD).

What’s the upshot here? I think that there is a spectrum of passivity and xenophobia in the modes of production outlined above. Sedentary peasant peoples are the most conservative and xenophobic.  They are also the least warlike because their skill set is the least transferable to warfare. They specialize in production, not extortion.

Pure nomads are the least xenophobic and most open to various forms of cultural innovation. The Mongol horde rapidly expanded in the decades of Genghis Khan’s rule through assimilation of various Turkic and Tungusic peoples. Though Genghis Khan put his sons by his first wife Borte in all the major positions, competent individuals outside of his own family line were elevated to power and authority. We have enough evidence now that these social dynamics are also strongly driven by the reality of migrating males, who marry a variety of conquered peoples.

Though Mongols were religiously tolerant and relatively accepting of ethnic diversity so long as subordinate peoples did not rebel, they were fundamentally an extortive order where organized mass violence was always the weapon of first resort. They were almost certainly not atypical, but continuing an Inner Asian tradition which probably dates to the Bronze Age, and matured 1,000 years later with groups like the Scythians.

Agropastoralists, such as the people of Nothern Europe during antiquity, were probably somewhere in between peasants and nomads. Not as xenophobic as peasants, but definitely more inward looking than the steppe nomads.

September 27, 2018

Do the northern Chinese have Scythian ancestors?

Filed under: China,Historical Population Genetics,Scythian — Razib Khan @ 2:32 pm

There was some question regarding possible Scythian admixture into the early Zhou below. This is possible because of the Zhou dynasty, arguably the foundational one of Chinese imperial culture (the Shang would have been alien to Han dynasty Chinese, but the Zhou far less so), may have had interactions with Indo-European peoples to their north and west. This has historical precedent as the Tang dynasty emerged from the same milieu 1,500 years later, albeit the Tang were descended from a Turkic tribe, not Indo-Europeans.

I looked at some of my samples and divided the Han into a northern and southern cluster based on their position on a cline (removing the majority in between). I also added Lithuanians, Sardinians, Uyghurs, Mongols, and Yakut. As you can see on the PCA the Mongols are two clusters, so I divided them between Mongol and Mongol2.

Running ADMIXTURE after some outlier removal you see that the northern Han are distinct because they share ancestry from the Yakut modal cluster. In contrast, the Mongols and Uyghurs have ancestry from the Lithuanian modal cluster. Uygurs also have quite a bit of ancestry from the Druze modal cluster, which is West Asian. Also notice that the Mongol2 cluster, which shares more ancestry with the Yakuts also has more Lithuanian modal cluster ancestry. Two of the Mongol2 individuals are labeled as Khalkha.

Using some of the Sarmatian/Scythian samples from David Reich’s lab, I ran ADMIXTURE again. These ancient samples need to be interpreted with caution, as usual. But notice again that the northern Han obtain their minor ancestry from the Yakut. The Iron Age nomadic modal ancestry is found at low levels in the Mongols and Uygurs. I think this is a real effect. The presence of Alans with the hordes of the Mongol Empire is well attested, though the admixture is almost certainly earlier.

I ran some three population tests. This is what was notable.

  1. Han_N looks like it is mixed somewhat with Yakut
  2. Mongol has gene flow from Mongol2
  3. Mongol2 has gene flow from Lithuanians and Iron Age nomads

I literally spend an hour on this assembling the data. But I think the easiest conclusion to draw is that the “West Eurasian” shift in modern Chinese (north) is probably mediated through Turkic people.

September 26, 2018

Vietnamese are not that much like the Cambodians

Filed under: Cambodia,Historical Population Genetics,Vietnam — Razib Khan @ 11:45 pm

A comment below suggested another book on Vietnamese history, which I am endeavoring to read in the near future. The comment also brought up issues relating to the ethnogenesis of the Vietnamese people, their relationship to the Yue (or lack thereof) and the Khmer, and also the Han Chinese.

Obviously, I can’t speak to the details of linguistics and area studies history. But I can say a bit about genetics because over the years I’ve assembled a reasonable data set of Asians, both public and private. The 1000 Genomes collected Vietnamese from Ho Chi Minh City in the south. I compared them to a variety of populations using ADMIXTURE with 5 populations.

Click to enlarge

You can click to enlarge, but I can tell you that the Vietnamese samples vary less than the Cambodian ones, and resemble Dai more than the other populations. The Dai were sampled from southern Yunnan, in China, and historically were much more common in southern China, before their assimilation into the Han (as well as the migration of others to Southeast Asia).

Curiously, I have four non-Chinese samples from Thailand, and they look to be more like the Cambodians. This aligns well with historical and other genetic evidence the Thai identity emerged from the assimilation of Tai migrants into the Austro-Asiatic (Mon and Khmer) substrate.

Aside from a few Vietnamese who seem Chinese, or a few who are likely Khmer or of related peoples, the Vietnamese do seem to have some Khmer ancestry. Or something like that.

Narrowing the populations, and using Indians as an outgroup, I wanted to test the Vietnamese against a few select populations. In the graph to the right you see that they are on the same branch as the Dai, and there is gene flow from the Dia into the Cambodians, and from the Cambodians into the Vietnamese. These results actually suggest that the Cambodians have had more gene flow in than the Vietnamese.

If you check the ADMIXTURE plot though you notice that there is a huge range of variation in the Cambodians in terms of their ancestry. The Mon kingdoms to the west of Cambodia fell to the Tai, but Cambodia itself did not. It probably absorbed a fair amount of Tai ancestry though, even if it retained its cultural distinctiveness and character.

A PCA shows that the Vietnamese are a distinct cluster. Different from both the Dai and South Chinese. Some of the samples in the 1000 Genomes are shifted toward the Cambodians and others toward the Chinese.

Finally, I ran a three population test. Here are some results of interest:

o3 pop1 pop2 f3 z
Cambodia Dai Indian -0.00175342 -25.8023
Cambodia French_Basque Dai -0.00192501 -22.1918
Cambodia Vietnamese Indian -0.00122671 -20.5523
Cambodia French_Basque Vietnamese -0.00136869 -17.6703
Cambodia Dai Papuan -0.0013018 -12.7299
Cambodia Han_S Indian -0.000790546 -10.365
Cambodia Vietnamese Papuan -0.000929681 -9.57058
Cambodia French_Basque Han_S -0.00087403 -9.24743
Cambodia Han_S Papuan -0.000476145 -4.05509
Dai Han_S Cambodia -0.000106184 -4.15877
Dai Cambodia She -0.000123515 -3.04445
Han_N French_Basque Han_S -0.000690947 -6.04291
Han_N Han_S Indian -0.000379328 -3.60634
Han_S Dai Han_N -0.000562373 -20.0654
Han_S Vietnamese Han_N -0.000425554 -15.6301
Han_S Filipino Han_N -0.000560061 -14.4192
Han_S Filipino Naxi -0.000529454 -10.9605
Han_S Malay Han_N -0.00038395 -10.3834
Han_S Dai Naxi -0.000316766 -9.36127
Han_S Filipino Yizu -0.000377863 -7.59642
Han_S Dai Yizu -0.000271844 -7.57112
Han_S Cambodia Han_N -0.000272892 -6.90769
Han_S Vietnamese Naxi -0.000211726 -6.09433
Han_S Vietnamese Yizu -0.000178654 -5.79285
Han_S Filipino Tujia -0.000175578 -4.66665
Han_S Thailand Han_N -0.000270477 -4.17533
Han_S Vietnamese Tujia -9.7422E-05 -3.79926
Han_S Tujia Dai -8.98028E-05 -3.0287
Han_S Tujia Malay -6.18931E-05 -1.67189
Han_S She Han_N -7.74747E-05 -1.41452
Han_S Filipino She -3.55034E-05 -0.888484
Vietnamese Han_S Cambodia -0.000646757 -34.4357
Vietnamese Han_S Malay -0.000420205 -22.545
Vietnamese Cambodia She -0.000615643 -17.2252
Vietnamese Tujia Cambodia -0.000553747 -15.6249
Vietnamese Malay She -0.000460983 -13.9445
Vietnamese Tujia Malay -0.000384676 -12.4208
Vietnamese Dai Indian -0.000494414 -12.4142
Vietnamese Cambodia Han_N -0.000494095 -12.2197
Vietnamese Miaozu Cambodia -0.000421982 -11.4913
Vietnamese Malay Han_N -0.000378602 -10.154
Vietnamese French_Basque Dai -0.000524036 -9.99871
Vietnamese Miaozu Malay -0.000280205 -8.27434
Vietnamese Dai Papuan -0.000339828 -5.83617
Vietnamese Han_S Indian -0.000210588 -4.70338
Vietnamese Dai Han_N -0.000122813 -4.42234
Vietnamese Malay Naxi -0.000152052 -3.8678
Vietnamese Han_S Thailand -0.000147552 -3.73211
Vietnamese Cambodia Yizu -0.000145687 -3.71074
Vietnamese Cambodia Naxi -0.000133426 -3.20226
Vietnamese Burm Dai -5.79109E-05 -3.12906
Vietnamese Dai Yizu -7.91838E-05 -3.00809

September 13, 2018

Avars across a sea of grass

Filed under: Avars,Historical Population Genetics — Razib Khan @ 10:29 pm

That sound you hear is the rumbling of the earth caused by the rippling tsunami that’s coming. The swell of ancient DNA papers focused on historical, rather than prehistorical, time periods. Some historians are cheering. Some are fearful. Others know not what to think. It will be. The illiterate barbarians of yore shall come out of the shadows.

If they had arrived on the edge of Europe two centuries earlier, the Avars would have a reputation as fearsome with the Huns, with whom they are often confused, and rightly so. But the Avars emerged as a force on the European landscape after the end of the West Roman Empire. The post-Roman polities did not have their own Ammianus Marcellinus (sorry Bede, you lived in the middle of nowhere).

And yet for centuries the Avars dominated east-central Europe and held the numerous Slavic tribes in thrall. They smashed past the borders of Byzantium during the reign of the heir of Justinian, and by 600 AD, on the eve of the great battle with Persia Constantinople had lost control of most of its Balkan hinterlands to these barbarians. A Byzantium which still controlled North Africa, much of Italy, southern Spain, Egypt, Anatolia, and the Levant, had been reduced to strongpoints all around the Balkan littoral. During the wars with the Sassanids, the Avars took advantage of the opportunity offered, and even raided the suburbs of Constantinople itself!

So who were these people? The most plausible conjecture is that they were part of the great mass mobilization of Turkic peoples which began in the early centuries of the first millennium after Christ. As Rome and Han China fell, nomadic barbarians rose. A new preprint seems to all but confirms this, Inner Asian maternal genetic origin of the Avar period nomadic elite in the 7th century AD Carpathian Basin:

After 568 AD the nomadic Avars settled in the Carpathian Basin and founded their empire, which was an important force in Central Europe until the beginning of the 9th century AD. The Avar elite was probably of Inner Asian origin; its identification with the Rourans (who ruled the region of today’s Mongolia and North China in the 4th-6th centuries AD) is widely accepted in the historical research. Here, we study the whole mitochondrial genomes of twenty-three 7th century and two 8th century AD individuals from a well-characterised Avar elite group of burials excavated in Hungary. Most of them were buried with high value prestige artefacts and their skulls showed Mongoloid morphological traits. The majority (64%) of the studied samples’ mitochondrial DNA variability belongs to Asian haplogroups (C, D, F, M, R, Y and Z). This Avar elite group shows affinities to several ancient and modern Inner Asian populations. The genetic results verify the historical thesis on the Inner Asian origin of the Avar elite, as not only a military retinue consisting of armed men, but an endogamous group of families migrated. This correlates well with records on historical nomadic societies where maternal lineages were as important as paternal descent.

The samples were from a period about a century after the arrival of the Avars. It is not unreasonable to think that the Avar conquest meant that a continuous stream of Inner Asian pastoralists kept entering into the territory which they occupied for the opportunity, but this sort of genetic distinctiveness indicates that the Avars remained very separate from the people from whom they extracted tribute. Most, though not all, of these people, were or became Slavs.

Around 800 AD the Avars were finally defeated decisively by the Franks, and their elite converted to Christianity. I suspect this was the final step which would result in their assimilation over the next few centuries into the location population until they diminished and disappeared.

The results above support the proposition that the Pannonian Avars of the second half of the 6th century were the descendants of the Rouran Khaganate of the early half 6th century. The kicker is that the Rouran flourished in Mongolia! So like the Mongols six hundred years later, the Avars seem to have swept across the entire length of Eurasia that was accessible to their horses in a generation. To some extent, this is a recapitulation of the pattern we see nearly 3,000 years before the Avar, when the Afanasievo culture established itself in the Altai region, far from its clear point of origin in the forest-steppe of Eastern Europe.

Perhaps the period between 500 BC and 300 AD can be seen as an ephemeral transient between the vast periods before and after when pastoralists had free reign across most of temperate Eurasia?

September 12, 2018

The genetics of Afrikaners (again)

Filed under: Afrikaner genetics,Historical Population Genetics — Razib Khan @ 10:18 pm
Click to enlarge

 

I personally get asked about the genetics of Afrikaners, because I’ve written about/analyzed the issue before. The main outlines seem to be established, but I thought I might go and revisit it again. The main reason is that we have ancient South African DNA, and I’ve been adding it to my personal analyses for a while. It might be worthwhile to reanalyze the South Africa samples I do have with some of these added in.

The plot at the top shows the core populations I started with. I did some outlier pruning. I only kept the South African samples that were overwhelmingly white. I picked Malays and a South Indian population because of Cape Coloureds, a mixed-race Afrikaans speaking group which has Asian ancestry that can be attributed to both South and Southeast Asian populations (the Dutch imported many slaves from India and had outposts in Java). I also used Bantu samples from South Africa, Kenya, as well as a Nigeria population. Finally, I also had some Hadza as a different hunter-gatherer population than the San Bushmen. For Europeans, I used white Dutch.

The final marker density as 200,000 SNPs, so not too bad.

As you can see if you click on the image all of the South African whites were shifted away from the Dutch. There were two outlier individuals, one of which was closer to the Dutch cluster, and one further. All the other individuals form a neat cluster. None of these individuals were close relatives.

Click to enlarge

I ran Treemix on the data with multiple migrations until the migrations stopped making sense to me. The African populations’ exhibit migration flows to each other. Much of it is entirely comprehensible. The Esan receive no migration, highlighting that this population did not receive gene flow from any groups in these data. The Kenya Bantus receive gene flow from the direction of Eurasians. This is also certainly Nilotic mediated. The gene flow they receive from the base of the ancient San is more enigmatic, but probably reflects uptake of local ancestry as the Bantus expanded. The southern Bantus receive gene flow from modern San.

The South African whites receive gene flow from a position on the graph between the modern San and other non-San African groups.

Click to enlarge

Next, I ran Admixture in the unsupervised mode with K = 6. The two populations mostly light-blue are South African whites and the Dutch, from the top to the bottom. You can see though that the South African whites clearly have other ancestral components. Most of these individuals have the components modal in the San, Esan Nigerians, Indians, and Malays. The two outlier individuals are also clear. The individual very close to the Dutch, but shifted toward the Asians, in the PCA does not have any African admixture. The individual shifted more toward the non-Europeans in the PCA also has more non-European fractions of ancestral components (that is, those components modal in non-European populations).

Next, I decided to confirm things by running a three population test. If you read this blog you’ve seen this before. Basically this is measuring shared ancestry by looking at deviations from a particular phylogenetic model: (test population(pop 1, pop2)). The relatedness of the test population to either pop1 or pop2 (that is, it’s a mix of the two) is measured by the negative f3 statistic, and I focused on z-scores greater than two.

Here they are:

Outgroup Pop1 Pop2 f3 z
Bantu_NE EsanNigeria Dutch -0.0009 -6.54
Bantu_NE EsanNigeria South_Africa_White -0.0010 -6.54
Bantu_NE EsanNigeria Malay -0.0009 -6.33
Bantu_NE EsanNigeria Telegu -0.0008 -6.00
Bantu_NE Bantu_S South_Africa_White -0.0008 -4.84
Bantu_NE Bantu_S Dutch -0.0008 -4.77
Bantu_NE Bantu_S Malay -0.0007 -4.21
Bantu_NE Bantu_S Telegu -0.0007 -4.05
Bantu_NE Dutch San_Ancient -0.0009 -3.02
Bantu_NE Hadza EsanNigeria -0.0004 -2.97
Bantu_NE Telegu San_Ancient -0.0007 -2.32
Bantu_NE Malay San_Ancient -0.0007 -2.04
Bantu_S EsanNigeria San_Modern -0.0028 -21.62
Bantu_S EsanNigeria San_Ancient -0.0039 -20.78
Bantu_S San_Ancient Bantu_NE -0.0030 -12.91
Bantu_S San_Modern Bantu_NE -0.0019 -12.45
Bantu_S Dutch San_Ancient -0.0031 -10.63
Bantu_S Telegu San_Ancient -0.0030 -10.33
Bantu_S San_Ancient South_Africa_White -0.0027 -9.17
Bantu_S Malay San_Ancient -0.0029 -8.97
San_Modern Dutch San_Ancient -0.0091 -34.96
San_Modern Telegu San_Ancient -0.0087 -33.86
San_Modern San_Ancient South_Africa_White -0.0089 -33.54
San_Modern San_Ancient Bantu_NE -0.0063 -31.93
San_Modern Malay San_Ancient -0.0085 -30.98
San_Modern Bantu_S San_Ancient -0.0052 -28.91
San_Modern Hadza San_Ancient -0.0051 -27.58
South_Africa_White Dutch Bantu_NE -0.0017 -12.96
South_Africa_White EsanNigeria Dutch -0.0017 -12.68
South_Africa_White San_Modern Dutch -0.0018 -12.41
South_Africa_White Bantu_S Dutch -0.0017 -12.36
South_Africa_White Dutch San_Ancient -0.0021 -12.14
South_Africa_White Hadza Dutch -0.0014 -10.41
South_Africa_White Malay Dutch -0.0007 -5.97
South_Africa_White Telegu Dutch -0.0003 -3.64
Telegu Malay Dutch -0.0004 -2.79

 

No surprises so far. One thing that did surprise me though was the extent of the admixture even after PCA outlier removal. So I took the output you saw above and removed individuals that were very mixed, except for the case of the white South Africans. Then, I ran admixture in supervised mode, where the “pure” populations were fixed as references (I merged the moden San without much admixture with the ancient San). You can see the results below:

Click to enlarge

Re-running the three population test with these “pure” populations I only got significant results for the below cases:

Outgroup Pop1 Pop2 f3 z
South_Africa_White Dutch EsanNigeria -0.0017 -13.1937
South_Africa_White San Dutch -0.0020 -12.6910
South_Africa_White Hadza Dutch -0.0014 -9.7246
South_Africa_White Malay Dutch -0.0009 -6.6481
South_Africa_White Telegu Dutch -0.0004 -4.6167

No big surprise.

The average European ancestry I got in my South African white samples, N = 12, is 93.5%. Making a composition individual, note that if someone had great-great-grandparents who were not European, they would be expected to have 6.25% non-European ancestry. That’s 4 generations back. So about 100 years. These individuals are presumably adults. Let’s say they are 25 years old. That goes back 125 years. It’s probably reasonable in a single person admixture people to suggest it was sometime in the mid to late 19th century.

This seems unlikely. The evenness of admixture and balance between different groups indicates that it is older than that, and they are obtaining it from different lineages. Traditional genealogical estimates suggested in the range of 5-7.5% non-European ancestry in Afrikaners, and one study of 185 individuals showed 18% non-European mtDNA.

I will probably some ancestry deconvolution and see if I can get a figure for the time of admixture (though the fractions here are very small, as is the sample size of the admixtured population). But the non-European ancestry of Afrikaners is uncannily similar to the non-European ancestry of the Cape Coloureds. That to me leads us to the conclusion that in the early European settler community a fair number of mixed-race women married in. Those mixed-race women who married mixed-race men helped found the Cape Coloureds.

August 12, 2018

Live not by the haplogroup alone

Filed under: Historical Population Genetics,Y chromosomes — Razib Khan @ 11:21 pm

In The population genomics of archaeological transition in west Iberia the authors note that “the population of Euskera speakers shows one of the maximal frequencies (87.1%) for the Y-chromosome variant, R1b-M269…” In the early 2000s the high frequency of R1b-M269 among the Basques, a non-Indo-European linguistic isolate, was taken to be suggestive of the possibility that R1b-M269 reflected ancestry from European hunter-gatherers present when farmers and pastoralists pushed into the continent.

The paper above shows that the reality is that the Basque people have higher fractions of Neolithic farmer ancestry than any other Iberian people. Additionally, they have lower fractions of the steppe pastoralist ancestry than other Iberian groups. This, despite the fact that we also know from ancient DNA that R1b-M269 does seem to have spread with steppe pastoralists, likely Indo-Europeans.

Obviously the relationship between Y chromosomes and genome-wide ancestry is complex. The pattern here for the indicates that Indo-European male lineages were assimilated into the Basques. Perhaps the Basque were matrilineal? One can’t know. But, these men did not impose their culture. Instead, they were assimilated into the Basque. This is entirely not shocking. There history of contact between different peoples in the recent past shows plenty of cases where individuals have “gone native.” In some cases, many individuals.

I was thinking this when looking at South Asian Y chromosome frequencies. Though R1a1a is correlated with higher castes and Indo-European speakers, its frequency is quite high in some ASI-enriched groups. I suspect that the period after 2000 BC down to the Common Era witness a dynamic where particular patrilineal societies were quite successful in maintain their status over generations. Additionally, the ethnogenesis of “Indo-Aryan” and “Dravidian” India was occurring over this period, in some cases through a process of expansion, integration, and conflict. It seems some pre-Aryan paternal lineages were assimilated into Brahmin communities. For example, Y haplogroup R2, whose origin is almost certainly in the Indus Valley Civilization society.

Some population genetic models are stylized and elegant. They have to be to be tractable. But we always need to remember that real history and prehistory were complex, and exhibited a richer and more chaotic texture.

June 19, 2018

Why the Y chromosome is coming back

Filed under: Historical Population Genetics,The Insight,Y chromosome — Razib Khan @ 6:43 am


Last week Spencer and I talked about chromosomes and their sociological import on The Insight. It was a pretty popular episode, but then again, my post on the genetics of Genghis Khan is literally my most popular piece of writing of all time which wasn’t distributed in a non-blog channel (hundreds of thousands of people have read it). Thanks to everyone who left a review on iTunes and Stitcher (well, a good review). We’re getting close to my goal of 100 reviews on iTunes and 10 on Stitcher so that I won’t pester you about it.

Of course the reality is that the heyday of  chromosomal population genetic studies was arguably about 15 years ago, when Spencer wrote The Journey of Man. I have personally constructed Y phylogenies before…but as you know from reading this weblog, I tend to look at genome-wide autosomal studies. There is a reason that why Who We Are and How We Got Here focuses on autosomal data.

All that being said, Y (and mtDNA) still have an important role to play in understanding the past: sociological dynamics. The podcast was mostly focused on star phylogenies, whether it be the Genghis Khan haplotype, or the dominant lineages of R1a and R1b. Strong reproductive skew does have genome-wide effects, but unless it’s polygyny as extreme as an elephant seal’s those effects are going to be more subtle than what you see in the Y and mtDNA.

Submitted for your approval, two recent preprints on bioRxiv: The role of matrilineality in shaping patterns of Y chromosome and mtDNA sequence variation in southwestern Angola and Cultural Innovations influence patterns of genetic diversity in Northwestern Amazonia. The future is going to be in understanding sexual dynamics and culture.

May 16, 2018

Migration at the roof of West Asia

Filed under: Historical Population Genetics,History,Indo-Europeans — Razib Khan @ 10:16 pm
Click to see the full figure

The figure to the left is from The genetic prehistory of the Greater Caucasus. If you are a regular reader of this weblog, or Eurogenes, you can figure out what’s going on, and keep track of the terminology. But in 2018 I think we’re getting to the end of the line in making sense of “admixture graphs” in relation to West Eurasian population structure. The models are just getting too complicated to keep everything straight, and the distinct-populations-subject-to-pulse-admixture seems to be an assumption that may not necessarily hold.

To get a sense of what I’m talking about, the above preprint focuses on populations in and around the Caucasus region. One of the major reasons that this is important is that the Caucasus was and is to some extent a continental hinge, connecting Eastern Europe and the Pontic steppe, to the Near East. The Arab Muslims pushed north of the Caucasus, and came into conflict with the Khazars, while Cimmerians and Scythians moved south from the Pontic steppe.

The elephant in the room is the relevance to the “Indo-European controversy.” Colin Renfrew long ago posited that the Indo-European languages derive from West Asian farmers who expanded into Europe as early as ~9,000 years ago. A rival theory is that Indo-Europeans spread out of the Pontic steppe ~4,000 years ago. In 2015 two major papers suggested that the steppe was a major source of Indo-European expansion. Case closed? This preprint suggests perhaps not.

But we’ll get to that later. What do the results here show? The prose is a little hard to tease apart, but the major issues seem to be that in antiquity, or at least the period they’re focusing on, much of the gene flow seems to have been south (Near East) to the north (through the Caucasus, and out to the north slope). To some extent, we already knew this: the Yamna people of the Pontic steppe have “southern” ancestry from the Near East that earlier East European/Pontic people do not. In this preprint, the authors show that groups such as the Maykop of the north slope of the Caucasus carry Y haplogroups such as G2, and not the R1 lineages commonly found in the steppe. David W. suggests that this confirms that Near Eastern gene flow into the steppe was female-mediated.  This is plausible, but I would caution that Y chromosomes alone can be deceptive, due to the power of particular patrilineages. We’ll probably rely on the X chromosome to make a final judgment.

The plot below shows many of the relationships as a function of location and time. The green component is modal among “Iranian farmers,” the orange among “Anatolian farmers,” and the blue among “Western hunter-gatherers.”

A major aspect of this preprint is that it has to work hard to differentiate two Anatolian farmer-like signals: the first, from Anatolian farmers proper, and the second from the descendants of European farmers, who themselves are a mix of Anatolian farmers with a minority ancestry among the hunter-gatherers. The answers would probably be totally unintelligible if not for archaeology. It’s clear that the steppe people had contact with both European and Near Eastern farmers and that later East European groups that succeeded the Yamna were subject to reflux from Central Europe, and received European farmer ancestry.

Another curious nugget in their results is that there was early detection of both Ancestral North Eurasian (ANE) ancestry and, some East Eurasian gene flow (related to Han Chinese). One of their individuals carries the East Eurasian variant of EDAR, which today is only found in Finns, though it was found in reasonable frequencies among the Motala hunter-gatherers of Scandinavia. Additionally, Fu et al. 2016 found that the ancestors of Mesolithic hunter-gatherers received some gene flow from Eastern Eurasians as well (also in the supplements of Lazaridis et al. 2016).

The authors admit that there is probably population structure among ANE and undiscovered groups of East Eurasians who were traversing the Inner Asian landscape. I think this is all suggestive of some long-distance contacts, though the intensity and magnitude increased a lot with high-density societies and the mobility of pastoralism.

Much of the genetic mixing in the Near East, and to some extent in the trans-Caucasian region, seems to date to the 4th millennium. This is technically prehistory, but it is also the Uruk period. This was a phase of Mesopotamian culture expansion between 4000 and 3100 BC which resulted in replicas of Uruk style settlements as far away as Syria and southeastern Anatolia. There is even evidence of Uruk-related migration to the North Caucasus.

The Uruk experienced abrupt and sudden collapse. Uruk settlements outside of the core zone of Mesopatamia disappear.

It’s the final paragraph that warrants discussion:

The insight that the Caucasus mountains served not only as a corridor for the spread of CHG/Neolithic Iranian ancestry but also for later gene-flow from the south also has a bearing on the postulated homelands of Proto-Indo-European (PIE) languages and documented gene-flows that could have carried a consecutive spread of both across West Eurasia…Perceiving the Caucasus as an occasional bridge rather than a strict border during the Eneolithic and Bronze Age opens up the possibility of a homeland of PIE south of the Caucasus, which itself provides a parsimonious explanation for an early branching off of Anatolian languages. Geographically this would also work for Armenian and Greek, for which genetic data also supports an eastern influence from Anatolia or the southern Caucasus. A potential offshoot of the Indo-Iranian branch to the east is possible, but the latest ancient DNA results from South Asia also lend weight to an LMBA spread via the steppe belt…The spread of some or all of the proto-Indo-European branches would have been possible via the North Caucasus and Pontic region and from there, along with pastoralist expansions, to the heart of Europe. This scenario finds support from the well attested and now widely documented ‘steppe ancestry’ in European populations, the postulate of increasingly patrilinear societies in the wake of these expansions (exemplified by R1a/R1b), as attested in the latest study on the Bell Beaker phenomenon….

But instead of tackling this let’s focus on the paper that came out of the Willerslev group, The first horse herders and the impact of early Bronze Age steppe expansions into Asia. This is a final manuscript in Science. That means it was probably written before The Genomic Formation of South and Central Asia. When it comes to South Asia, the results from the two publications are consanant. There is no conflict.*

More interesting are the results in West Asia, and the linguistic supplement. In the authors note that tablets now indicate an Indo-Aryan presence in Syria ~1750 BC. Second, Assyrian merchants record Indo-European Hittite, or Nesili (the people of Nesa), as early as ~2500 BC.

As suggested in earlier work Hittite remains don’t suggest steppe influence. David W. says:

The apparent lack of steppe ancestry in five Hittite-era, perhaps Indo-European-speaking, Anatolians was interpreted in Damagaard et al. 2018 as a major discovery with profound implications for the origin of the Anatolian branch of Indo-European languages.

But I disagree with this assessment, simply because none of these Hittite-era individuals are from royal Hittite, or Nes, burials. Hence, there’s a very good chance that they were Hattians, who were not of Indo-European origin, even if they spoke the Indo-European Hittite language because it was imposed on them.

The main aspect I’d bring up with this is that in other areas steppe ancestry has spread deeply and widely into the population, including non-Indo-European ones. It is certainly possible that the sample is not needed enough to pick up the genuinely Hittite elite, but I probably lean to the likelihood that the steppe signal won’t be found. It seems that the Anatolian languages were already diversified by ~2000 BC, and perhaps earlier. Linguists have long suggested that they are the outgroup to other Indo-European languages, though this could just be a function of their isolation among highly settled and socially complex populations.

Two alternative models present themselves for these results. The Anatolian Indo-European languages expanded through elite diffusion,  part of the same general migrations that emerged out of the Yamna culture ~3000 BC. The lack of a steppe signal may be due to sampling bias, as David W. suggested, or, more likely in my opinion, simple dilution of the signal. Second, the steppe migrations were one part of a broader palette of population movements and cultural diffusions, and the Anatolian Indo-Europeans are basal to the efflorescence of the steppe derived branches.

The evidence of the explosion of Indo-Aryans in the years after 2000 BC in West and South Asia, as well as the expansion of Iranians across vast swaths of Inner Asia during the same period, suggest to me that Indo-Iranians are most definitely part of the steppe pulse. The connection to the Sintashta charioteers presents itself, and, connections to the Uralic languages indicates incubation in the trans-Volga region.

In West Asia, the Indo-Aryans crashed themselves against the most advanced civilizations of their time. Like the Bulgars, and unlike the Hittites, Indo-Aryan Mitanni was totally absorbed by their non-Indo-European Hurrian substrate. Indo-Aryan linguistic influence was preserved in their names, their gods, and in particular words relating to chariots. And yet in 2017’s Continuity and Admixture in the Last Five Millennia of Levantine History from Ancient Canaanite and Present-Day Lebanese Genome Sequences, the authors observe:

We next tested a model of the present-day Lebanese as a mixture of Sidon_BA and any other ancient Eurasian population using qpAdm. We found that the Lebanese can be best modeled as Sidon_BA 93% ± 1.6% and a Steppe Bronze Age population 7% ± 1.6% (Figure 3C; Table S6). To estimate the time when the Steppe ancestry penetrated the Levant, we used, as above, LD-based inference and set the Lebanese as admixed test population with Natufians, Levant_N, Sidon_BA, Steppe_EMBA, and Steppe_MLBA as reference populations. We found support (p = 0.00017) for a mixture between Sidon_BA and Steppe_EMBA which has occurred around 2,950 ± 790 ya (Figure S13B).

This needs to be more explored. The admixture could have come from many sources. I am curious about the frequency of R1a1a-z93 among modern-day Syrians and Lebanese.

For me these arguments can only be resolved with a deeper understanding of linguistic evolution. The close relationship of Indo-Aryan and Iranian languages is obvious to any speaker of either of these languages (I can speak some Bengali). A divergence in the range of 4 to 5 thousand years before the present seems most likely to me. But the relationship of the other Indo-European languages is much less clear.

One of the arguments in Peter Bellwood’s First Farmers is that the Indo-European languages exhibit a “rake-like” topology with the exception of Indo-Iranian, which forms a clear clade. To him and others in his camp, this argues for deep divergences very early in time.

It is hard to deny that the steppe migrations between 4 and 5 thousand years ago had something to do with the distribution of modern Indo-European languages. But, it is harder to falsify the model that there were earlier Indo-European migrations, perhaps out of the Near East, that preceded these. Only a deeper understanding of linguistic evolution, and multidisciplinary analysis of regional substrates will generate the clarity we need.

* I’m going to skip the Botai angle in this post.

April 30, 2018

Is American genetic diversity enough?

Filed under: Historical Population Genetics,Human Genetic Variation — Razib Khan @ 8:51 pm


In the nearly 20 years since the draft of the human genome was complete,* we’ve moved on to bigger and better things. In particular, researchers are looking to diversify their panels of human genetic diversity, because of differences between groups matter. You can’t just substitute them for each other genetically.

There have been efforts to diversify the population panels recently, but that prompts the question whether American population coverage is sufficient. My first thought is that the genetic diversity in the USA is probably getting us 90% of the way there. Consider Spencer’s comment about Queens, it’s the most ethnically diverse large conurbation in the country.

There are some gaps though. In Who We Are David Reich points out the distinctiveness of Indian population genetics. The subcontinent has lots of large census populations which have drifted upward deleterious alleles due to long-term endogamy. And, many of these populations don’t have a strong representation in the Diaspora.

In contrast, much of the rest of the world is panmictic enough that an American panel can pick up most of the variation. American Chinese are skewed toward Guandong and Fujian, but a substantial number of people from other parts of China have arrived in the last generation. Regional structure is not so strong that you’ll miss out on too much, aside from very rare variants which are more extended pedigree scale rather than population scale.

There are small populations such as Hadza, Khoikhoi, and Pygmies in Africa which are probably going to be missed by American population panels, but the total census size of these groups is pretty low (for comparison, there are 1 million Pulayar Dalits in the state of Kerala alone). Much of the rest of Africa is West African variation well represented in African Americans, and Bantu and Nilotic variation probably captured my immigrant communities.

I’d propose supplementing American genetic diversity with sampling Cape Coloureds in South Africa.

* No discussions about how the genome isn’t totally complete. I know that.

February 24, 2018

Are Turks Armenians under the hood?

Filed under: Historical Population Genetics,Population genetics — Razib Khan @ 8:31 pm

Benedict Anderson’s Imagined Communities: Reflections on the Origin and Spread of Nationalism is one of those books I haven’t read, but should. In contrast, I have read Azar Gat’s Nations, which is a book-length counterpoint to Imagined Communities. To take a stylized and extreme caricature, Imagined Communities posits nations to be recent social and historical constructions, while Nations sees them as primordial, and at least originally founded on on ties of kinships and blood.

The above doesn’t capture the subtlety of  Gat’s book, and I’m pretty sure it doesn’t capture that of Anderson’s either. But, those are the caricatures that people take away and project in public, especially Anderson’s (since Gat’s is not as famous).

When it comes to “imagined communities” I recently have been thinking how much that of modern Turks fits into the framework well. Though forms of pan-Turkic nationalism can be found as earlier as 9th-century Baghdad, the ideology truly emerges in force in the late 19th century, concomitantly with the development of a Turkish identity in Anatolia which is distinct from the Ottoman one.

The curious thing is that though Turkic and Turkish identity is fundamentally one of language and secondarily of religion (the vast majority of Turkic peoples are Muslim, and there are periods, such as the 17th century when the vast majority of Muslims lived in polities ruled by people of Turkic origin*), there are some attempts to engage in biologism. This despite the fact that the physical dissimilarity of Turks from Turkey and groups like the Kirghiz and Yakut is manifestly clear.

Several years ago this was made manifestly clear in the paper The Genetic Legacy of the Expansion of Turkic-Speaking Nomads across Eurasia. This paper clearly shows that Turkic peoples across Eurasia have been impacted by the local genetic substrate. In plainer language, the people of modern-day Turkey mostly resemble the people who lived in Turkey before the battle of Manzikert and the migration of Turkic nomads into the interior of the peninsula in the 11th century A.D. Of course, there is some genetic element which shows that there was a migration of an East Asian people into modern day Anatolia, but this component in the minority one.**

Sometimes the Turkish fascination with the biological comes out in strange ways, Turkish genealogy database fascinates, frightens Turks. Much of the discussion has to do with prejudice against Armenians and Jews. But the reality is that most Turks at some level do understand that they are descended from Greeks, Armenians, Georgians, etc.

To interrogate this further I decided to look at a data set of Greeks, Turks, Armenians, Georgians, and a few other groups, including Yakuts, who are the most northeastern of Turkic peoples. The SNP panel was >200,000, and I did some outlier pruning. Additionally, I didn’t have provenance on a lot of the Greeks, except some labeled as from Thessaly. I therefore just split those up with “1” being closest to the Thessaly sample and “3” the farthest.

First, let’s look at the PCA.

The Turks are shifted toward the Yakuts, but not too much. In contrast, there is much more of Yakut shift in Tajiks, and especially Turkmens. These are two groups from further east, closer to the heart of the zone Turkic expansion. Curiously, the Tajiks, who are the dominant non-Turkic Iranian speaking people of Central Asia, actually have more East Asian ancestry than the Turks of Turkey. This goes to show that ethnicity is somewhat fluid, and Turkic people have assimilated into the Tajik identity. That being said, please note that the Turkmen are notably more east-shifted than the Tajik.

Let’s see how this looks on pairwise Fst.

Fst is kind of difficult for fine distinctions when you have outgroups like Yakuts and Dai. So let’s look at Treemix with five migrations:

On this, you can see that the relationship of the Greece clusters on Treemix to Lithuanians matches PCA. Greece1 is the closest, Greece 3 the farthest.

The Turks are close to the Georgians and Armenians, but not the Kurds, or Tajiks. And, they receive gene flow from the Turkmen-Yakut region of the graph. So do the Tajiks…but the Tajiks also remove gene flow from the Lithuanians. The admixture plot makes it more clear what’s happening I think.

Yellow ~ modal in Southern Europe, green ~ modal Northern Europe, red ~ Central Asian, while blue and purple are northern and southern East Asian. In comparison to Turks of Anatolia Tajiks have a lot more Northern European affinity, probably because of the common steppe heritage. Not surprisingly, Turks have more Southern European like ancestry.

Curiously the East Asian ancestry in the Turkic people seems to be both Yakut and Dai like, so perhaps it was more cosmopolitan than we might think? The Yakuts after all are from the northern edge of the range, and may have absorbed a lot of indigenous Siberian ancestry.

Georgians have none of the Northern European sort of ancestry, but Armenians do, and Turks even more. One could posit that this is due to Slavic ancestry arriving with the Rumelian Turks who arrived in the 20th century, but just as likely is the possibility that Turks have a lot of ancestry from western Anatolia which was Greek, and Greeks have more of this than Armenians.

It’s hard to tell from these results whether Turks have more of an affinity with Greek or Armenians as their non-Turkic ancestors. So I ran a three population test.

Outgroup X1 X2 f3 error z
Turkey Armenians Yakut -0.00253688 6.70852e-05 -37.8158
Turkey Greece3 Yakut -0.00246931 6.72384e-05 -36.7247
Turkey Georgian Yakut -0.00256555 7.60158e-05 -33.7502
Turkey Armenians Dai -0.00246779 7.40038e-05 -33.3468
Turkey Greece3 Dai -0.0024101 7.34629e-05 -32.8071
Turkey Georgian Dai -0.00249174 8.11957e-05 -30.688
Turkey Greece2 Yakut -0.00222382 7.62368e-05 -29.1699
Turkey Greece2 Dai -0.00231001 8.39207e-05 -27.5261
Turkmen Turkey Dai -0.00288213 0.000108049 -26.6742
Turkmen Turkey Yakut -0.00254805 0.000102816 -24.7826
Turkey Greece1 Yakut -0.00225638 9.94722e-05 -22.6836
Turkey GreekCentral Dai -0.00235681 0.000104014 -22.6587
Turkey Greece3 Tajik -0.000622671 2.76666e-05 -22.5063
Turkey GreekCentral Yakut -0.00221985 0.000101654 -21.8373
Turkey Greece1 Dai -0.00243254 0.000112011 -21.717
Turkey Greece3 Turkmen -0.000640439 3.33529e-05 -19.2019
Turkey GreekThessaly Yakut -0.00208436 0.00011042 -18.8767
Turkey Dai GreekThessaly -0.00225435 0.00012241 -18.4163
Turkey Greece2 Turkmen -0.000584983 3.29819e-05 -17.7365
Turkey Armenians Turkmen -0.000520887 3.07253e-05 -16.953
Turkey Armenians Tajik -0.000421139 2.55274e-05 -16.4975
Tajik Turkey Dai -0.00140423 8.51697e-05 -16.4875
Tajik Turkey Yakut -0.00124601 7.60725e-05 -16.3793
Turkey Georgian Turkmen -0.000532496 3.80694e-05 -13.9875
Turkey Greece2 Tajik -0.000412419 3.04172e-05 -13.5587
Turkey Armenians Lithuanians -0.000459831 3.75838e-05 -12.2348
Turkey Greece1 Turkmen -0.000570715 4.7753e-05 -11.9514
Turkey Kurds Yakut -0.00146087 0.000124799 -11.7058
Turkey GreekThessaly Turkmen -0.000516877 4.46683e-05 -11.5714
Turkey Georgian Tajik -0.000328859 3.02443e-05 -10.8734
Turkey GreekCentral Turkmen -0.000504962 4.92555e-05 -10.2519

Armenians beat out Greece3 a bit better, but really it’s hard to say from this that this is definitive. It’s likely that my Turkish sample has both, and/or the original Turkic nomads had Iranian-like ancestry which was more like Armenian than Greek? Hard to say. Additionally, the face that Greece3 is better than the other options suggests to me that the source are Anatolian Greeks who were less impacted by migrations from the north than Greeks in Greece proper.

 

* The Mughals were Central Asian Turks, while the Safavids were mostly Azeri Turks.

** Since the Turks who arrived in Anatolia had long sojourned in Turn and Iran it is important not to assume that their contribution is limited only to the East Asian component of ancestry.

February 22, 2018

Mesolithic and Paleolithic, Of Cheddar and Bread

Filed under: Cheddar Man,Historical Population Genetics,Neolithic — Razib Khan @ 7:27 pm


It’s been a big week for “Cheddar Man” and the science around him. I already talked about the issue blog-wise for my day job. Additionally, Spencer and I did a podcast on the topic (if you haven’t, please subscribe and leave positive reviews and ratings on iTunes and Stitcher; next we’ll post our conversation with Chris Stringer, don’t miss it!).

So at this point I’ll put some other thoughts here that are “big picture.”

Cheddar Man may have been black but probably wasn’t

Much of the media is focused on the predicted pigmentation of Cheddar Man. That is, dark. Back when the La Brana Western Hunter-Gatherer results came in with the same finding, several population genomics people pointed out that it might not be valid to predict their phenotype based on modern training sets.

Here are some thoughts:

  • Cheddar Man and the WHG in general were probably darker than modern Northern Europeans. There is detectable selection in modern Europeans for pigmentation alleles down to the present, and Northern Europeans are the palest people in the world. And, pigmentation is polygenic, but it’s not hyperpolygenic. That’s why GWAS and early selection tests picked up pigmentation loci as hits so often.
  • Cheddar Man and the WHG in general were probably not as dark as tropical people. The only people who live(d) at very high latitudes who were very darkly complected were Tasmanian Aboriginals and Australian Aboriginals (Melbourne is at the same latitude south as Lisbon is north). In contrast, we see that Khoisan are brown, sometimes rather lightly so, while the peoples of non-European heritage who live in high latitudes are not dark-skinned, though they are not as light-skinned as Europeans.

We don’t have a time machine, so we won’t know with finality. But, it seems that pigmentation pathways are finite, and eventually we can probably be more confident if Cheddar Man had a genetic architecture that would lead to fewer and smaller melanocytes.

The First Farmers replaced WHG to a great extent in Britain

The preprint that came out with the Cheddar Man documentary really focused mostly on the Neolithic farmers. The data set was large, and it emphasized that the discontinuity between the farmers, who were EEF from Anatolian stock (modern Sardinians are their best proxies), the hunter-gatherers. WHG is genetically homogeneous, so they couldn’t reject the proposition that there was no admixture of British hunter-gatherers into the farmer population Basically, the thesis that Peter Bellwood outlined in First Farmers is well supported by these results. The farmers brought agricullture, and pushed aside or absorbed the hunter-gatherers.

It is notable to me that they found more hunter-gatherer ancestry (possibly) in eastern and northern populations, but not much in farmers from Wales. Additionally, though they couldn’t be definitive about it, the EEF settlers of Britain seem to have more affinities with the Western Mediterranean populations than the Central European ones. This suggests that perhaps the farmers arrived by sea or coast-hugging from the south and west, rather than from the south and east.

The arrival of farming to Britain was different

Farmers came to Britain later than to the continent. The shift from hunter-gatherer to farming was rapid. One model for why there was lack of admixture is that the farming cultural package was fully adapted to Northern Europe by the time they began settling the island. In contrast, on the mainland farmers were changing a Middle Eastern lifestyle into something that could take root in cold northern climes where there were already local residents.

Sometimes cultural and ecological changes drive rapid expansions of human populations

Today Europe, and much of Western Eurasia, is characterized by isolation by distance dynamics between populations. What you see in the transition from the Mesolithic to the Neolithic, and later with the arrival of metal age populations (Bell Beakers), is that populations can turnover fast, and that rapid expansion and growth can result in homogeneity across huge distances and then sharp continuities across cultural divides. The classical example of this is that hunter-gatherers and farmers in Central Europe did not exchange much in the way of genes for centuries, and their between population variance accounted for ~10% of their pooled variance (this is what you see comparing Han and Europeans). Additionally, WHG and EEF are both relatively homogeneous, at least before the latter began to absorb WHG at different fractions across its range. WHG descends from a late Pleistocene expansion, after the Last Glacial Maximum. Similarly, the EEF expanded rapidly from its Anatolian point of origin.

Britons didin’t become Britons genetically until the Bronze Age

Ten years ago many people thought at Cheddar Man and his people were the ancestors of most of the people who lived in Britain today. At the same time as this preprint came out, the Bell Beaker paper was officially published. We now know that Britain went through two massive demographic transitions in less than 2,000 years, with on the order of a 90% replacement in a few centuries both times.

Why? Was this typical? Those are for a later post….

January 30, 2018

The “Finns” are probably an Iron Age intrusion into the East Baltic

Filed under: Finns,Historical Population Genetics — Razib Khan @ 10:23 pm

One of the first things I wrote at length about historical population genetics, in late 2002, happened to be a rumination on the Y chromosomal phylogeography of Finnic peoples. At the time there was debate as to the provenance of the N1c Y chromosomal haplotype (this is the haplotype of the Rurikids by the way). Just as R1b is ubiquitous in Western Europe, and R1a in Eastern Europe (and to some extent in Indo-Iranian lands), N1c has an extensive distribution in the northern zone of Eurasia.

The question at the time was whether N1c was from Europe and in particular the Finnic peoples, or, whether it was from Siberia.

NJ Tree of Pairwise Fst

Today we have many of the questions resolved. At this point, we know that the Finns, Sami, and Estonians, all exhibit evidence of gene flow from a Siberian-like population. This is clear on any genome-wide analyses. Though this is very much a minority component, even among the Sami, because it is genetically very different from the Northern European background, it is clear on any analysis.

Ancient DNA has also established the likelihood that this Siberian-like element is relatively new to the Baltic region. In a recent paper, The genetic prehistory of the Baltic Sea region:

We suggest that the Siberian and East Asian related ancestry in Estonia, and Y-haplogroup N in north-eastern Europe, where it is widespread today, arrived there after the Bronze Age, ca. 500 calBCE, as we detect neither in our Bronze Age samples from Lithuania and Latvia.

This is not the only ancient DNA paper that shows this. Of course, sampling is imperfect, and perhaps they’ve missed pockets of ancient Finnic peoples. But the most thorough analysis of Mesolithic hunter-gatherers in Scandinavian does not pick them up either, Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation. Populations, such as the Comb Ceramic Culture, which have been identified as possible ancestors of the modern Finnic culture and ethnicity, lack the distinctive Siberian-like component.

At the SMBE 2017, I saw a poster which had results that were sampled from Finland proper, and distinctive ancestry of Siberian-like peoples was present in an individual who lived after 500 AD. This means that in all likelihood the circumpolar Siberian population which introduced this new element into the East Baltic arrived in the period between 500 BC and 500 AD.

Someone with more knowledge of paleoclimatology and archaeology needs to comment at this point. Something happened in this period, and it probably left a big ethno-linguistic impact. But I don’t know enough detail to say much (the Wikipedia entries are out of date or don’t illuminate).

I will add when I run Treemix Finns get the Siberian gene flow you’d expect. But the Lithuanians get something from the Finns. Since the Lithuanians have appreciable levels of N1c, that is not entirely surprising to me (the basal flow from the Yakut/European region to Belorussians may be more CHG/ANE).

Additionally, I will note that on a f-3 test Lithuanians have nearly as high a z-score (absolute) as Swedes (i.e., Finn; Swede/Lithuanian, Yakut), indicating that the predominant Northern European ancestry isn’t necessarily Scandinavian, as much as something between Lithuanian-like and Swedish-like (on Admixture tests the Finns do seem to have less EEF than Swedes, and Lithuanians probably the least of all among non-Finn peoples).

Addendum: I should note here that the genetics is getting clearer, but I have no great insight into the ethno-linguistic aspect. Perhaps the Siberian-like people did not introduce Finnic languages into the Baltic. Perhaps that was someone else. But I doubt it. That being said, though the Siberian-like component adds great distinctiveness to the Finns, it is important to add that by and large Finns are actually generic (if highly drifted) Northern Europeans.

 

January 23, 2018

Function & phylogeny, where the twain shall diverge

Filed under: Historical Population Genetics,Kalash,Nuristani — Razib Khan @ 11:03 pm


Every few years I get asked about Nuristanis and Kalash. The reason is that these people are often white. By white, I mean that some Nuristanis and Kalash are fair-skinned, blonde-haired, and blue-eyed. Entering “Nuristani” into Google images returns some very white faces. And you have weird news stories about ‘white’ Taliban, because non-locals don’t realize that some Nuristanis look like Northern Europeans.

Since the vast majority of people who look like white Northern Europeans are white Northern Europeans, many people assume that the Nuristanis and Kalash must have some kinship to white Northern Europeans. More precisely, many have spread the legend that these people have some relationship to the soldiers of Alexander the Great (even though Macedonians are Southern European…details).

As it turns out, they do have some kinship to Europeans…but not inordinately more than any of the other peoples of the region. The TreeMix plot at the top of this post shows that Greeks are far closer to Iranian Jews than they are to Kalash. In fact, the Kalash clearly have a non-trivial proportion of “Ancestral South Indian” South Asian ancestry.

Because of their high genetic drift (they’re endogamous and kind of inbred) a lot of population genetic analyses are a bit more difficult with the Kalash samples that are out there. But their genetic affinities are clear:

Table S4 show highly significant evidence (p value < 10−10) in the Kalash when using Armenia and Chamar as surrogates. Eight other pairings of surrogates give p values < 10−5. In all cases, the surrogate pairs include one group from South Asia (Chamar, Kol) and the other from West Eurasia (Armenia, Adygei, Brahui, Hungarians, Palestinians, Tuscans), consistent with admixture from a West Eurasian source.

Chamar are a Dalit caste of Northern India if you don’t know.

So what’s going on with the Kalash and Nuristanis? Appreciable frequencies of alleles which are correlated with traits like blue-eyes are found amongst them. Though the frequencies are much lower than in Northern Europeans. Very white looking Nuristanis and Kalash may be highly salient to photographers and the Western media, but it turns out most Nuristanis and Kalash look West Asian, with a minority who are dark-skinned enough that their South Asian ancestry is also quite clear.

This disjunction between appearance and ancestry should not surprise us. There has been a lot of recent change in physical appearance across populations over the last 10,000 years. Europeans themselves have changed in appearance. Similarly, other populations have as well. Some of them look similar to Europeans due to happenstance or convergence.

Another case are the Ainu of Japan. Though as an unadmixed group they no longer exist, old photos show some of them exhibiting an appearance not typical of East Asians. This led early anthropologists to posit that the Ainu were a “lost white race.” And yet to my knowledge, no European ancestry is found in Hokkaido, or in the Tohoku region, where Ainu-like people lived down to the early medieval period.

The moral of the story: don’t judge the contents of the book by its cover.

January 20, 2018

The eastern edge of the sea of grass

Filed under: Historical Population Genetics,Magyars — Razib Khan @ 1:50 pm

A new preprint, Mitogenomic data indicate admixture components of Asian Hun and Srubnaya origin in the Hungarian Conquerors, throws a rather large sample of medieval mtDNA samples at the question of the ethnogenesis of the Magyar people. The context here is that Maygars speak a non-Indo-European language, with a distant relationship to the Finnic ones, but genetically are not much distinguished from their neighbors.

But the differences are not non-zero, ‘best of breed’ methods can pick up a small fraction of exotic ancestry.

The results above are based on samples from cemeteries of the Magyar elite. These are people who identified with a steppe confederacy which coalesced in the 9th century in the Volga region, and in 895 conquered the region of Central Europe which we now term Hungary. In the 10th century, the Magyar tribes were an alien and predatory force within Europe, pagan and exotic. They were, in fact, the latest in a long time of mobile Central Asian horsemen, going back to the Scythian, Sarmatians, Huns, and Avars.

What the data from these results confirm is that a substantial proportion of the maternal lineages of the Hungarian nobility were East Eurasian. Their genetic profiles, in fact, resembled Scythians who had mixed with Altaic peoples, even if they were not descended from those people. What this suggests is that the Magyar conquest elite was part of a broader landscape of ethnolinguistically distinct, but interconnected, steppe confederations. The preprint gives great space to the likelihood that a substantial proportion of the Magyar elite was in fact Turkic in origin.

This leads to one of the major assertions of the paper: the distinctive linguistic identity of modern Hungarians is a legacy of the Hunnic period, and not the Magyar conquest. From what I can tell they didn’t have older DNA, so I don’t know how they came to this conclusion, except that the conquest Magyars were small in number, and seem to have been decimated over time (Mongol invasion, the battle of Mohacs).

May 9, 2017

The Beaker is breaking!

The link is up, The Beaker Phenomenon And The Genomic Transformation Of Northwest Europe, but the paper is still processing:

I’ll update the post when I can read the paper.

September 18, 2011

The words of the father

Over at A Replicated Typo they are talking about a short paper in Science, Mother Tongue and Y Chromosomes. In it Peter Forster and Colin Renfrew observe that “A correlation is emerging that suggests language change in an already-populated region may require a minimum proportion of immigrant males, as reflected in Y-chromosome DNA types.” But there’s a catch: they don’t calculate a correlation in the paper. Rather, they’re making a descriptive verbal observation. This observation seems plausible on the face of it. In addition to the examples offered, one can add the Latin American case, where mestizo populations tend to have European Y chromosomal profiles and indigenous mtDNA.


In one of the more nuanced instances cited by Renfrew and Forster they note that though there is a fair penetration of both Austronesian mtDNA and Y chromosomes amongst Austronesian speaking inhabitants of New Guinea, Austronesian Y chromosomes are nearly absent from those populations which speak Papuan. In other words, the inference is that the native indigenous male elite perpetuated the Papuan language! I think the key issue here is social dominance, and the role of male cultural units. This is clear when you have a group like African Americans. Though mostly West African in ancestry this ethnic group clearly has ~20% European ancestry, mostly mediated through European males. This is simply a function of the social dominance of European males in relation to African males. And, it may be telling that African Americans are an English speaking Christian population, albeit with their own distinctive accent.

In the paper the authors note:

…It may be that during colonization episodes by emigrating agriculturalists, men generally outnumbered women in the pioneer colonizing groups and took wives from the local community. When the parents have different linguistic backgrounds, it may often be the language of the father that is dominant within the family group….

There is certainly some truth to this. But what I think that this narrative misses are the coarser and larger scale social units which expansive male cultural communities operate through. The spread of European males in Latin America was not uncoordinated. Often small groups of males decapitated indigenous male power elites, sometimes literally! Long distance travel, such as what the Austronesians engaged in, almost certainly must have entailed a minimal level of political and ideological commitment. They cite the example of the Genghis Khan haplotype, but that wasn’t perpetuated through a process of gradual demic expansion.

August 24, 2011

The geography of genes tells us only so much about history

Filed under: Historical Population Genetics,Human Genetics,Population genetics — Razib Khan @ 10:29 pm

L. L. Cavalli-Sforza’s The History and Geography of Human Genes is a book I reference a great deal. Cavalli-Sforza is the godfather of the field of historical population genetics, the phylogeography of humankind. Though his work was on classical autosomal markers, the huge literature which drew inferences from Y chromosomal and mtDNA variation followed in the wake of the The History and Geography of Human Genes. Spencer Wells, the director of the Genographic Project, alluded to Cavalli-Sforza’s influence in The Journey of Man. But at this point I think we have to be very careful of making inferences about the past from present patterns of genetic variation. This is made most stark by the fact that ancient DNA, which is a snapshot of the past, as opposed to an inference of it, sometimes diverges from our expectations based on present patterns of variation in surprising ways.


This to me is the big lesson to draw from a new paper in The Proceedings of the Royal Society B, The peopling of Europe and the cautionary tale of Y chromosome lineage R-M269. The results focus on two issues. First, the distribution ...

June 23, 2011

Celts to Anglo-Saxons, in light of updated assumptions

Over the past week there have been three posts which I’ve put up which are related. Two of them have a straightforward relation, Britons, English, Germans, and collective action and Britons, English, and Dutch. But the third might not seem related to the other two, We stand on the shoulders of cultural giants, but it is. When we talk about things such as the spread of language through “elite emulation” or “population replacement” they’re rather vague catchall terms. We don’t decompose them mechanistically into their components to explore whether they can explain what they purport to explain. Rather, we take these phenomena for granted in a very simplistic black box fashion. We know what they’re describing on the face of it. “We” here means people without a background in sociolinguistics, obviously.

To give an example of the pitfall of this method, in much of Rodney Stark’s work on sociology of religion (the production before his recent quasi-apologetic material) his thinking was crisp and logical, but the psychological models were intuitive and naive and tended to get little input from the latest findings in cognitive science. In One True God he actually offers an explanation for why ...

December 30, 2010

Are Turks acculturated Armenians?

To the left you see a zoom in of a PCA which Dienekes produced for a post, Structure in West Asian Indo-European groups. The focus of the post is the peculiar genetic relationship of Kurds, an Iranian-speaking people, with Iranians proper, as well as Armenians (Indo-European) and Turks (not Indo-European). As you can see in some ways the Kurds seem to be the outgroup population, and the correspondence between linguistic and genetic affinity is difficult to interpret. For those of you interested in historical population genetics this shouldn’t be that surprising. West Asia is characterized by of endogamy, language shift, and a great deal of sub and supra-national communal identity (in fact, national identity is often perceived to be weak here). A paper from the mid-2000s already suggested that western and eastern Iran were genetically very distinctive, perhaps due to the simple fact of geography: central Iran is extremely arid and relatively unpopulated in relation to the peripheries.

But this post isn’t about Kurds, rather, observe the very close relationship between Turks and Armenians on the PCA. The _D denotes Dodecad samples, those which Dienekes himself as collected. This affinity could easily be predicted by the basic parameters of physical geography. Armenians and Anatolian Turks were neighbors for nearly 1,000 years. Below is a map which shows the expanse of the ancient kingdom of Armenia:

Historic Armenia was centered around lake Van in what is today eastern Turkey. The modern Republic of Armenia is very much a rump, and an artifact of the historic expansion of the Russian Empire in the Caucasus at the expense of the Ottomans and Persians. Were it not for the Armenian genocide there may today have been more Armenians resident in Turkey than in the modern nation-state of Armenia,* just as there are more Azeri Turks in Iran than in Azerbaijan. Many areas once occupied by Armenians are now occupied by Kurds and Turks. But a bigger question is the ethnogenesis of the Anatolian Turkish population over the past 1,000 years.

Dienekes has already shed light on this topic earlier, adding the Greek and Cypriot populations to the mix as well as Turks and Armenians. The disjunction between Kurds and the Armenian-Turk clade suggests to us that Turks did not emerge out of the milieu of Iranian tribes in the uplands of southeast Anatolia and western Persia. Like the Armenians the Kurds are an antique population, claiming descent from the Medes, and referred to as Isaurians during the Roman and Byzantine period.

Below is a reformatted K = 15 run of ADMIXTURE with Eurasian population. I’ve removed the labels for the ancestral components, but included in populations which have a high fraction of a given ancestral component. The geographical labels are for obscure populations. I’ve underlined the four populations of interest:

First, let’s get out of the way the fact that Turkish samples have non-trivial, though minor, northeast Asian ancestry. The Yakut themselves are a Turkic group situated to the north of Mongolia. The more southerly and central Asian affinities the nomadic ancestors of the Anatolia Turks may have picked up in their sojourns over the centuries between their original homeland in east-central Siberia and Mongolia and West Asia. The rest of ancestry is rather typical of northern West Asian groups. In particular, Armenians! Here is the ancestral breakdown for the four groups I want to focus on using Dienekes’ labels:


Population Greek Cypriots Turks Armenians
West Asian 37.6 54.1 47.2 56.3
Central-South Asian 5.3 8.6 18.2 18.4
North European 25.1 5.6 12 12.3
South European 27.4 20.8 9.4 8.4
Arabian 3.4 8 4.3 3.4
Altaic 0.3 0 2.6 0.1
East Asian 0.3 0.2 2.2 0
Central Siberian 0.1 0.2 1.4 0.2
Chukchi 0 0 1.1 0.2
South Indian 0 0.1 0.8 0.3
Nganasan 0.1 0 0.4 0.2
Koryak 0.1 0 0.2 0.1
East African 0 0.4 0.1 0
West African 0 0 0.1 0
Northwest African 0.3 1.9 0.1 0

And now the correlations between the populations by ancestral components:



Greek Cypriots Turks Armenians
Greek * 0.863 0.823 0.813
Cypriots * * 0.941 0.946
Turks * * * 0.997
Armenians * * * *

Let’s remove the East Eurasian and African components, and recalculate the proportions by taking what remains as the denominator:


Population Greek Cypriots Turks Armenians
West Asian 38.1 55.7 51.8 57.0
Central-South Asian 5.4 8.9 20.0 18.6
North European 25.4 5.8 13.2 12.4
South European 27.7 21.4 10.3 8.5
Arabian 3.4 8.2 4.7 3.4

And the recomputed  correlations:



Greek Cypriots Turks Armenians
Greek * 0.747 0.640 0.647
Cypriots * * 0.901 0.908
Turks * * * 0.999
Armenians * * * *

With all the ~0 ancestral components which were common across these four populations removed the correlations have gone down. Except in the case of the Armenian-Turk pair, because I’ve removed the ancestries which differentiate them.

So what’s a plausible interpretation? A straightforward one would be that the Muslim Turk population of Anatolia has a strong bias toward having been assimilated Armenians, rather than Greeks. The cultural plasticity of Armenians in late antiquity and the early medieval period was clear: individuals of ethnic Armenian to origin rose the pinnacles of the status hierarchy of the Orthodox Christian Greek Byzantine Empire. The Macedonian dynasty of the Byzantines under which the civilization reached its mature peak were descended from Armenians who had resettled in Macedonia. Just as plausible to me is that eastern Anatolia as a whole exhibited little genetic difference between Greeks and Armenians, and the former were wholly assimilated or migrated, while the Armenians remained. One way to test this thesis would be type the descendants of Greeks who left eastern Anatolia during the population exchange between Greece and Turkey in the 1920s. But the difference between Greeks and Cypriots also points us to another possibility: perhaps the Greeks of Greece proper (as opposed to Anatolia) were much more strongly impacted by the arrival of Slavs? One need not necessarily rely solely on the Scalveni migrations either, water tends to be a major dampener to conventional isolation-by-distance gene flow, so the Greek mainland may always have been subject to more influence from the lands to the north.

Whatever the details of ethnogenesis may be, it will be interesting to see how things shake out as we increase sample sizes and get better population coverage. These results may be due to regional selection bias. One might expect that the descendants of Rumelian Turks be more “European” than Anatolian Turks. But, these data do seem to suggest on face value that Armenians are the population which Anatolian Turks have the most genetic affinity with.

* My main hesitation would be that Armenians are a very mobile population, and their numbers within a modern Turkey may have declined simply through emigration, just as those of Christian Arabs have over the 20th century.

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