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Wednesday, January 31, 2018

Modern-day Poles vs Bronze Age peoples of the East Baltic


Below are three of my staple Principal Component Analyses (PCA) featuring Baltic Bronze Age (Baltic_BA) samples from the recent Mittnik et al. 2018 paper (open access here). On each of the plots I've also highlighted modern-day Balts and Poles. The latter two PCA also include most of the other ancients from the said paper (listed here). They're not highlighted, but all of the relevant datasheets are available here, here and here, and easy to plot with the Past software.

No doubt, these Bronze Age peoples of the East Baltic, and in particular the four individuals from Turlojiske, Lithuania, are very closely related to modern-day Balts and northern Slavs. They may well be our ancestors, or at least close relatives thereof. This is argued and demonstrated well enough by Mittnik et al., and it clearly shows in my PCA, especially the first one, which is designed to focus on entho-linguistic-specific genetic drift in Northern Europe.




Nevertheless, overall, they do clearly show a higher cut of indigenous European Hunter-Gatherer ancestry relative to modern-day Northeast Europeans (note how in the second PCA the Baltic_BA samples pull towards the European Hunter-Gatherers compared to Balts and especially Poles). I'm not exactly sure what the explanation is for this yet. Indeed, there might be several different explanations. But generally speaking, it's probably in large part the result of post-Bronze Age gene flow into the Baltic region from Central Europe.

See also...

Early Baltic Corded Ware form a genetic clade with Yamnaya, but...

The genetic history of Northern Europe (or rather the South Baltic)

Genetic and linguistic structure across space and time in Northern Europe

Tuesday, January 2, 2018

On the genomic history of North Eurasia (Triska et al. 2017)


Over at BMC Genetics at this LINK. The accompanying dataset is freely available here, although it includes less than 300K SNPs, so the overlap with the Human Origins and EGDP datasets isn't great. Emphasis is mine:

Background: The history of human populations occupying the plains and mountain ridges separating Europe from Asia has been eventful, as these natural obstacles were crossed westward by multiple waves of Turkic and Uralic-speaking migrants as well as eastward by Europeans. Unfortunately, the material records of history of this region are not dense enough to reconstruct details of population history. These considerations stimulate growing interest to obtain a genetic picture of the demographic history of migrations and admixture in Northern Eurasia.

Results: We genotyped and analyzed 1076 individuals from 30 populations with geographical coverage spanning from Baltic Sea to Baikal Lake. Our dense sampling allowed us to describe in detail the population structure, provide insight into genomic history of numerous European and Asian populations, and significantly increase quantity of genetic data available for modern populations in region of North Eurasia. Our study doubles the amount of genome-wide profiles available for this region.

We detected unusually high amount of shared identical-by-descent (IBD) genomic segments between several Siberian populations, such as Khanty and Ket, providing evidence of genetic relatedness across vast geographic distances and between speakers of different language families. Additionally, we observed excessive IBD sharing between Khanty and Bashkir, a group of Turkic speakers from Southern Urals region. While adding some weight to the “Finno-Ugric” origin of Bashkir, our studies highlighted that the Bashkir genepool lacks the main “core”, being a multi-layered amalgamation of Turkic, Ugric, Finnish and Indo-European contributions, which points at intricacy of genetic interface between Turkic and Uralic populations. Comparison of the genetic structure of Siberian ethnicities and the geography of the region they inhabit point at existence of the “Great Siberian Vortex” directing genetic exchanges in populations across the Siberian part of Asia.

Slavic speakers of Eastern Europe are, in general, very similar in their genetic composition. Ukrainians, Belarusians and Russians have almost identical proportions of Caucasus and Northern European components and have virtually no Asian influence. We capitalized on wide geographic span of our sampling to address intriguing question about the place of origin of Russian Starovers, an enigmatic Eastern Orthodox Old Believers religious group relocated to Siberia in seventeenth century. A comparative reAdmix analysis, complemented by IBD sharing, placed their roots in the region of the Northern European Plain, occupied by North Russians and Finno-Ugric Komi and Karelian people. Russians from Novosibirsk and Russian Starover exhibit ancestral proportions close to that of European Eastern Slavs, however, they also include between five to 10 % of Central Siberian ancestry, not present at this level in their European counterparts.

Conclusions: Our project has patched the hole in the genetic map of Eurasia: we demonstrated complexity of genetic structure of Northern Eurasians, existence of East-West and North-South genetic gradients, and assessed different inputs of ancient populations into modern populations.

Triska et al., Between Lake Baikal and the Baltic Sea: genomic history of the gateway to Europe, BMC Genetics, 2017 18(Suppl 1):110, https://doi.org/10.1186/s12863-017-0578-3

Monday, June 19, 2017

Polish aDNA PCA


Below is a Principal Component Analysis (PCA) that I put together for an upcoming presentation on Polish ancient DNA (aDNA). The five RISE samples are from Allentoft et al. 2015, including RISE569, the early Slavic genome from the Czech Republic, which was initially wrongly labeled as a Czech Bell Beaker (see here). PL_N17 is an Early Bronze Age (EBA) sample from Gustorzyn, Northern Poland (see here).


I also organized f3 outgroup statistics of the form f3(European_pop,Test,Yoruba) for each of these samples to compare their genetic affinities to present-day European populations. Although f3 outgroup statistics aren't as sensitive as haplotype tests, I think these results look interesting and useful, with both PL_N17 and RISE569 seemingly showing strong links to modern-day West Slavs. The full output is available in a zip file here.

Poland_EBA PL_N17
Lithuanian 0.175778
Ukrainian_West 0.174866
Sorb 0.174334
Estonian 0.174313
Icelandic 0.17397
Irish 0.173863
Polish_West 0.173743
Polish_East 0.173549
Czech 0.173545
Norwegian 0.173533

Early Slav RISE569
Sorb 0.169171
Lithuanian 0.168945
Estonian 0.168819
Polish_West 0.168267
Polish_East 0.168143
Irish 0.168092
Czech 0.167941
Norwegian 0.167787
Icelandic 0.167696
Finnish 0.167685

See also...

Testing for genetic continuity in Poland from the Bronze Age to the present

Saturday, May 20, 2017

Shared maternal ancestry between Slavs and Germanics probably dates to the Metal Ages


Over at the Russian Journal of Genetics behind a paywall at this LINK. Emphasis is mine:

Abstract: The structure and diversity of mitochondrial DNA (mtDNA) macrohaplogroup U lineages in Russians from Eastern Europe are studied on the basis of analysis of variation of nucleotide sequences of complete mitochondrial genomes. In total, 132 mitochondrial genomes belonging to haplogroups U1, U2e, U3, U4, U5, U7, U8a, and K are characterized. Results of phylogeographic analysis show that the mitochondrial gene pool of Russians contains mtDNA haplotypes belonging to subhaplogroups that are characteristic only of Russians and other Eastern Slavs (13.7%), Slavs in general (11.4%), Slavs and Germans (17.4%), and Slavs, Germans, and Baltic Finns (9.8%). Results of molecular dating show that ages of mtDNA subhaplogroups to which Russian mtDNA haplotypes belong vary in a wide range, from 600 to 17000 years. However, molecular dating results for Slavic and Slavic-Germanic mtDNA subhaplogroups demonstrate that their formation mainly occurred in the Bronze and Iron Ages (1000–5000 years ago). Only some instances (for subhaplogroups U5b1a1 and U5b1e1a) are characterized by a good agreement between molecular dating results and the chronology of Slavic ethnic history based on historical and archaeological data.

Malyarchuk, B.A., Derenko, M.V. & Litvinov, The macrohaplogroup U structure in Russians, A.N. Russ J Genet (2017) 53: 498. doi:10.1134/S1022795417020053

Tuesday, May 16, 2017

Globular Amphora people starkly different from Yamnaya people


The figure below is from the recent Mathieson et al. 2017 preprint; slightly edited to highlight the results of nine Globular Amphora Culture (GAC) samples from two burial sites in what are now Poland and Ukraine.


Despite living in East Central Europe at about the same time as the nearby Yamnaya people of the Pontic-Caspian Steppe, these GAC individuals show practically zero Yamnaya-related or steppe ancestry (note the almost total absence of the orange "Yamnaya" component in the Globular_Amphora results in the ADMIXTURE bar graph). Instead, they're very similar to Chalcolithic and Middle Neolithic Central and Western Europeans, with whom they overlap in the Principal Component Analysis (PCA).

During the tail end of the GAC period, East Central Europe was suddenly dominated by a new archaeological complex called the Corded Ware Culture (CWC). Although most CWC individuals sampled to date show minor GAC-related ancestry, they're overwhelmingly Yamnaya-like, which suggests that by and large the CWC population has its origins on the Pontic-Caspian Steppe. In fact, some of the earliest CWC examples from the Baltic States, such as Latvia_LN in the ADMIXTURE bar graph, are basically identical to Yamnaya people.

It was suggested not long ago that the presence of Yamnaya-related ancestry in modern-day Europeans could be mostly explained by the so called Isolation-by-Distance phenomenon (see here). But as I said at the time, this was a major faux pas, and thanks to these GAC samples I now have direct evidence from ancient DNA to back me up. So forget the idea of anything resembling a gentle cline in Yamnaya-like ancestry east to west across Europe before proto-CWC and Yamnaya exploded from the steppes.

By the way, in that critique I said that it's not possible to recapitulate ancient populations with ADMIXTURE components. I stand by that statement, although as we can see in Mathieson et al. 2017, it is possible to get close at times with enough of the right ancient samples; close enough to make some general observations anyway.

Interestingly, on the PCA plot, the European Bronze Age cluster is more or less half way between GAC and Latvia_LN. This is also where modern-day Poles and Ukrainians cluster on such plots when they're not significantly skewed by projection bias or shrinkage. Thus, I do wonder if the Slavs of East Central Europe are essentially a 50/50 mixture of early CWC and late GAC? I'll try and test this when the Mathieson et al. 2017 dataset goes online.

Reference...

Mathieson et al., The Genomic History Of Southeastern Europe, bioRxiv, Posted May 9, 2017, doi: https://doi.org/10.1101/135616

See also...

Late PIE ground zero now obvious; location of PIE homeland still uncertain, but...

Tuesday, March 28, 2017

Hints of deep genetic substructure in Iron Age Poland


A paper at Infection, Genetics and Evolution looks at the susceptibility to infectious diseases in two late Iron Age groups from Central Poland. I can't wait to see genome-wide and Y-chromosome data from these and other ancient Polish populations. Judging by the outcomes presented in this paper, and also rumors that I've heard from Polish labs, we're in for some major surprises. Emphasis is mine:

Abstract: For thousands of years human beings have resisted life-threatening pathogens. This ongoing battle is considered to be the major force shaping our gene pool as every micro-evolutionary process provokes specific shifts in the genome, both that of the host and the pathogen. Past populations were more susceptible to changes in allele frequencies not only due to selection pressure, but also as a result of genetic drift, migration and inbreeding. In the present study we have investigated the frequency of five polymorphisms within innate immune-response genes (SLC11A1 D543N, MBL2 G161A, P2RX7 A1513C, IL10 A-1082G, TLR2 –196 to –174 ins/del) related to susceptibility to infections in humans. The DNA of individuals from two early Roman-Period populations of Linowo and Rogowo was analysed. The distribution of three mutations varied significantly when compared to the modern Polish population. The TAFT analysis suggests that the decreased frequency of SLC11A1 D543N in modern Poles as compared to 2nd century Linowo samples is the result of non-stochastic mechanisms, such as purifying or balancing selection. The disparity in frequency of other mutations is most likely the result of genetic drift, an evolutionary force which is remarkably amplified in low-size groups. Together with the FST analysis, mtDNA haplotypes' distribution and deviation from the Hardy-Weinberg equilibrium, we suggest that the two populations were not interbreeding (despite the close proximity between them), but rather inbreeding, the results of which are particularly pronounced among Rogowo habitants.

...

Although no sound evidence of population differentiation was found when comparing the samples of Linowo and Rogowo, it is worth noticing that the distribution of mtDNA haplotypes between these two settlements differs remarkably. Apart from the two haplotypes (rCRS and 16126C) that occur in both studied groups, no other pattern of mtDNA SNPs is shared between them. The lack of reflection of these dissimilarities in the FST analysis is probably a result of the low-size group which is more exposed to result bias or low diversity of haplotypes among Rogowo individuals. All of the above allows to draw the theoretical conclusion that although these two settlements date back to the same period and are located within 55 km (or around 160 km along the Vistula River) of one another, they are genetically remote.

Lewandowska et al., The genetic profile of susceptibility to infectious diseases in Roman-Period populations from Central Poland, Infection, Genetics and Evolution, Volume 47, January 2017, Pages 1–8, http://dx.doi.org/10.1016/j.meegid.2016.11.011

See also...

R1a-Z280 from Early Bronze Age Northern Poland

Wednesday, July 27, 2016

Lipka Tatars vs Balto-Slavs


Huge difference in this ADMIXTURE bar graph from the recent Pankratov et al. paper between Lipka Tatars from Belarus and nearby Balts and Slavs. The Lipka Tatars are almost identical to Volga Tatars despite residing in their current homeland for about 500 years. I'm guessing the fact that they're Sunni Muslims might have something to do with it.


Pankratov, V. et al. East Eurasian ancestry in the middle of Europe: genetic footprints of Steppe nomads in the genomes of Belarusian Lipka Tatars. Sci. Rep. 6, 30197; doi: 10.1038/srep30197 (2016).

Saturday, June 18, 2016

Poles in the new Human Origins dataset


Harvard's Human Origins dataset is being updated with 238 new samples, including 23 from Poland (15 from Poznan in western Poland and 8 from Lublin in eastern Poland). It should be available for download soon at the Reich Lab website here, although many of the new samples will only be accessible to people who sign a waiver. Below is a Principal Component Analysis (PCA) from Lazaridis et al. 2016 featuring the new samples. Interestingly, most of the Poles, probably those from Poznan, cluster with Sorbs from eastern Germany.


Citation...

Lazaridis et al., The genetic structure of the world's first farmers, bioRxiv preprint, posted June 16, 2016, doi: http://dx.doi.org/10.1101/059311

Sunday, May 1, 2016

Ancient Polish admixture in Denmark


This ESHG 2016 presentation about Danish population structure is sure to be interesting. I wonder how the authors were able to discern ancient Polish admixture from more recent Polish admixture? Keep in mind that lots of Poles settled in Denmark during the past 150 years or so. For instance, former Danish national team goalkeeper Peter Schmeichel is half Polish. And Caroline Wozniacki is totally Polish.

Abstract: Denmark’s genetic history has never been studied in detail. In this work, we analysed genetic and anthropometrical data from ~800 Danish students as part of an outreach activity promoting genomic literacy in secondary education. DNA analysis revealed remarkable homogeneity of the Danish population after discounting contributions from recent immigration. This homogeneity was reflected in PCA and AMOVA, but also in more sophisticated LD-based methods for estimating admixture. Notwithstanding Denmark’s homogeneity, we observed a clear signal of Polish admixture in the East of the country, coinciding with historical Polish settlements in the region before the Middle Ages. In addition, Denmark has a substantially smaller effective population size compared to Sweden and Norway, possibly reflecting further lack of strong population structure. None of these three Scandinavian countries seems to have suffered a depression due to the Black Death in the Middle Ages. Finally, we used the students’ genetic data to predict their adult height after training a novel prediction algorithm on public summary statistics from large GWAS. We validated our prediction using the students’ self-reported height and found that we could predict height with a remarkable ~64% accuracy.

Athanasiadis et al., Nationwide genomic study in Denmark reveals remarkable population homogeneity, ESHG EMPAG 2016 Presentation Abstract, P18.091C


Update 24/08/2016: The paper is now available at Genetics and open access. See here: On the remarkable genetic homogeneity of Denmark.

Monday, March 21, 2016

Scandinavians in medieval Poland


The genetic evidence presented in this paper is underwhelming; a single, low resolution mtDNA haplogroup I haplotype that appears to be of Scandinavian origin because it was also found in remains from Iron Age Denmark (sample B5 in Melchior et al. 2008). However, the authors' conclusions are also based on archaeological evidence, and they also match recent isotopic results (see here).

Abstract: Contemporary historical anthropology and classical archaeology are concerned not only with such fundamental issues as the origins of ancient human populations and migration routes, but also with the formation and development of inter-population relations and the mixing of gene pools as a result of inter-breeding between individuals representing different cultural units. The contribution of immigrants to the analysed autochthonous population and their effect on the gene pool of that population has proven difficult to evaluate with classical morphological methods. The burial of one individual in the studied Napole cemetery located in central Poland had the form of a chamber grave, which is typical of Scandinavian culture from that period. However, this fact cannot be interpreted as absolute proof that the individual (in the biological sense) was allochtonous. This gives rise to the question as to who was actually buried in that cemetery. The ancient DNA results indicate that one of the individuals had an mtDNA haplotype typical of Iron Age northern Europe, which suggests that he could have arrived from that area at a later period. This seems to indirectly confirm the claims of many anthropologists that the development of the early medieval Polish state was significantly and directly influenced by the Scandinavians.

Płoszaj T. et al., Analysis of medieval mtDNA from Napole cemetery provides new insights into the early history of Polish state, Ann Hum Biol. 2016 Mar 11:1-4., DOI:10.3109/03014460.2016.1151550