search this blog

Monday, December 22, 2014

Ancient East European and West Asian admixture deep in Siberia


The full mito sequences from this new Derenko at al. study should come in very handy when many more ancient genomes from across North Eurasia are published. The paper is open access, but here are a few excerpts anyway:

Although the genetic heritage of aboriginal Siberians is mostly of eastern Asian ancestry, a substantial western Eurasian component is observed in the majority of northern Asian populations. Traces of at least two migrations into southern Siberia, one from eastern Europe and the other from western Asia/the Caucasus have been detected previously in mitochondrial gene pools of modern Siberians.

We report here 166 new complete mitochondrial DNA (mtDNA) sequences that allow us to expand and re-analyze the available data sets of western Eurasian lineages found in northern Asian populations, define the phylogenetic status of Siberian-specific subclades and search for links between mtDNA haplotypes/subclades and events of human migrations. From a survey of 158 western Eurasian mtDNA genomes found in Siberia we estimate that nearly 40% of them most likely have western Asian and another 29% European ancestry. It is striking that 65 of northern Asian mitogenomes, i.e. ~41%, fall into 19 branches and subclades which can be considered as Siberian-specific being found so far only in Siberian populations. From the coalescence analysis it is evident that the sequence divergence of Siberian-specific subclades was relatively small, corresponding to only 0.6-9.5 kya (using the complete mtDNA rate) and 1–6 kya (coding region rate).

...

Overall, the phylogeographic analysis strongly implies that the western Eurasian founders, giving rise to Siberian specific subclades, trace their ancestry only to the early and mid-Holocene, though some of genetic lineages may trace their ancestry back to the end of LGM. Importantly, we have not found the modern northern Asians to have western Eurasian genetic components of sufficient antiquity to indicate traces of pre-LGM expansions, that originated from the Upper Paleolithic industries present both in the southern Siberia and Siberian Arctic, and that date back to ~30 kya, well before the LGM [43]–[45]. Apparently, the Upper Paleolithic population of northern Asia, whose western Eurasian ancestry was approved recently by complete genome sequencing of 24 kya-old individual from Mal’ta and 17 kya-old individual from Afontova Gora in south-central Siberia, did not leave a genetic mark on the female lineages of modern Siberians. It is probable that the initial population expansion in the southern Siberia region involved maternal lineages other than present now, or that there was a substantial gene flow into the region after the LGM, most probably from eastern Asian sources as have been suggested by Raghavan et al. [7].

Citation...

Derenko et al.: Western Eurasian ancestry in modern Siberians based on mitogenomic data. BMC Evolutionary Biology 2014 14:217. doi:10.1186/s12862-014-0217-9

Thursday, October 23, 2014

Ancient DNA from Iron Age and Medieval Poland


A new paper at PLoS ONE featuring ancient mitochondrial (mtDNA) data from Wielbark, Przeworsk and early Slavic remains argues for matrilineal continuity in present-day Poland since the Iron Age. It's actually based on a thesis that I blogged about more than two years ago (see here). However, it does include some fresh insights, so it's worth a look even if you read the thesis. RoIA stands for Roman Iron Age.

Three modern populations or groups of populations (Lithuanians and Latvians, Poles, and Czechs and Slovaks) were found to contain significantly higher percentages (p,0.05) of shared informative haplotypes with the RoIA samples compared to other present-day populations (Figure 2, Table S4). Notably, modern Poles shared the highest number (nine) of informative mtDNA haplotypes with the RoIA individuals.

...

Of particular interest are three RoIA samples assigned to subhaplogroup H5a1, which were recovered from the Kowalewko (sample K1), the Gaski, and the Rogowo (samples G1 and R3) burial sites (see Figure 1). Recent studies on mtDNA hg H5 have revealed that phylogenetically older subbranches, H5a3, H5a4 and H5e, are observed primarily in modern populations from southern Europe, while the younger ones, including H5a1 that was found among RoIA individuals in our study, date to around 4.000 years ago (kya) and are found predominantly among Slavic populations of Central and East Europe, including contemporary Poles [15]. Notably, we also found one ME sample belonging to subhaplogroup H5a1 (sample OL1 in Table 3). The presence of subclusters of H5a1 in four ancient samples belonging to both the RoIA and the ME periods, and in contemporary Poles, indicates the genetic continuity of this maternal lineage in the territory of modern-day Poland from at least Roman Iron Age i.e., 2 kya.

...

The evolutionary age of H5 sub-branches (,4 kya) [15] also approximates the age of N1a1a2 subclade found in the RoIA population (sample KA2) (Table 2). The coalescence age of N1a1a2 is around 3.4–4 kya, making this haplotype one of the youngest sub-branches within hg N [52]. The N1a1a2 haplotype found in one RoIA individual was classified as unique because no exact match was found among the twelve comparative populations or groups of populations used in the haplotype sharing test. Notably, a similar N1a1a2 haplotype carrying an additional transition at position 16172 was found in a modern-day Polish individual [53].

I suspect the publication of these results at this time, so many months after they were first revealed in the aforementioned thesis, is part of an effort to drum up interest and secure funding for a new project on the genetic history of Greater Poland, which was announced late last year (see here). I say that because one of the people organizing the project, Janusz Piontek, is also listed as a co-author on this paper. So if we're lucky we might soon see full genome sequences from a few of these Iron Age and Medieval samples.

Citation...

Juras A, Dabert M, Kushniarevich A, Malmstro¨m H, Raghavan M, et al. (2014) Ancient DNA Reveals Matrilineal Continuity in Present-Day Poland over the Last Two Millennia. PLoS ONE 9(10): e110839. doi:10.1371/journal.pone.0110839

Sunday, September 21, 2014

Corded Ware people: more versatile and healthier than Neolithic farmers


Over at West Hunter Greg Cochran argues that late Neolithic farmers in Northern Europe experienced nothing short of genocide at the hands of Corded Ware Culture (CWC) pastoralists, who pushed deep into the continent from somewhere east of present-day Germany around 4,800 years ago.

I think he's exaggerating. My view is that farming populations throughout much of Neolithic Europe began to crash well ahead of any invasions, perhaps as a result of climate change, overpopulation, environmental degradation and bad health. This, I'd say, created a vacuum that attracted groups from the peripheries of the Neolithic world, like the CWC nomads.

If so, it's likely that many of the surviving farmers were killed or marginalized in the process, although their women might have been incorporated on a large scale into the new post-Neolithic societies. This is perhaps why the most common Neolithic Y-chromosome haplogroup, G2a, is now so scarce in Europe, while a wide variety of mitochondrial (mtDNA) lineages frequently found among Neolithic skeletons are still carried by many Europeans today.

Nevertheless, I'm not aware of any evidence of a wholesale slaughter, or even any wars, going on in Europe during the early CWC period.

This new paper at Anthropologie seems to back up my case. The Corded Ware people were simply more versatile and healthier than the Neolithic farmers. No wonder then, that they eventually came out on top.

This study focuses on the changes in the human skeleton that are associated with the transition to agricultural subsistence. Two populations from the territory of contemporary Poland that differ in terms of their subsistence strategies are compared. An agricultural subsistence strategy is represented by a Lengyel Culture population from Oslonki (5690-4950 BP), whilst the Corded Ware populations from Zerniki Gorne and Zlota (c. 4160-3900 BP) represent mixed, agricultural-breeding-pastoral economies supplemented with hunting and gathering. The Corded Ware sample consisted of 62 individuals in total, and the Lengyel sample comprised 68 individuals. Health status was examined through skeletal stress indicators, cribra orbitalia, enamel hypoplasia and Harris lines. The analysis of enamel hypoplasia showed the effect of different adaptive strategies on buffering adverse nutritional factors and diseases. The prevalence and severity of the condition proved significantly higher in the Lengyel sample than in the Corded Ware population (64.7% vs. 43.5%, respectively). It is suggested that agricultural subsistence, associated with a less diversified diet, sedentism, exposure to pathogens, spread of infections and increased population density, caused more frequent and severe stress episodes than the mixed economy of the Corded Ware people. The inverse relationship between enamel hypoplasia and the mean age at death found in the agricultural population clearly shows an effect of adverse living conditions on the biological development of the individuals studied.

Citation...

Krenz-Niedbala M, A biocultural perspective on the transition to agriculture in Central Europe, Anthropologie, 2014/Volume 52/Issue 2/pp. 115-132, ISSN 0323-1119

See also...

Best of 2008: Corded Ware DNA from Germany

Corded Ware Culture linked to the spread of ANE across Europe

Wednesday, August 13, 2014

Male height in Europe


A new paper in the Economics & Human Biology journal argues that male height in Europe is mostly determined by nutrition and genetics. That's not exactly earth shattering news. However, the authors also point out that Y-chromosome haplogroup I-M170 shows a strong correlation with the highest average stature on the continent, and speculate that the link between the two might be Upper Paleolithic hunter-gatherer ancestry:

The average height of 45 national samples used in our study was 178.3 cm (median 178.5 cm). The average of 42 European countries was 178.3 cm (median 178.4 cm). When weighted by population size, the average height of a young European male can be estimated at 177.6 cm. The geographical comparison of European samples (Fig. 1) shows that above average stature (178+ cm) is typical for Northern/Central Europe and the Western Balkans (the area of the Dinaric Alps). This agrees with observations of 20th century anthropologists (Coon, 1939; Lundman 1977). At present, the tallest nation in Europe (and also in the world) are the Dutch (average male height 183.8 cm), followed by Montenegrins (183.2 cm) and possibly Bosnians (182.5 cm) (Table 1). In contrast with these high values, the shortest men in Europe can be found in Turkey (173.6 cm), Portugal (173.9 cm), Cyprus (174.6 cm) and in economically underdeveloped nations of the Balkans and former Soviet Union (mainly Albania, Moldova, and the Caucasian republics).

...

The trend of increasing height has already stopped in Norway, Denmark, the Netherlands, Slovakia and Germany. In Norway, military statistics date its cessation to late 1980s.

...

In contrast, the fastest pace of the height increase (≥1 cm/decade) can be observed in Ireland, Portugal, Spain, Latvia, Belarus, Poland, Bosnia and Herzegovina, Croatia, Greece, Turkey and at least in the southern parts of Italy.

...

Although the documented differences in male stature in European nations can largely be explained by nutrition and other exogenous factors, it is remarkable that the picture in Fig. 1 strikingly resembles the distribution of Y haplogroup I-M170 (Fig. 10a). Apart from a regional anomaly in Sardinia (sub-branch I2a1a-M26), this male genetic lineage has two frequency peaks, from which one is located in Scandinavia and northern Germany (I1-M253 and I2a2-M436), and the second one in the Dinaric Alps in Bosnia and Herzegovina (I2a1b-M423)16. In other words, these are exactly the regions that are characterized by unusual tallness. The correlation between the frequency of I-M170 and male height in 43 European countries (including USA) is indeed highly statistically significant (r = 0.65; p < 0.001) (Fig. 11a, Table 4). Furthermore, frequencies of Paleolithic Y haplogroups in Northeastern Europe are improbably low, being distorted by the genetic drift of N1c-M46, a paternal marker of Ugrofinian hunter-gatherers. After the exclusion of N1c-M46 from the genetic profile of the Baltic states and Finland, the r-value would further slightly rise to 0.67 (p < 0.001). These relationships strongly suggest that extraordinary predispositions for tallness were already present in the Upper Paleolithic groups that had once brought this lineage from the Near East to Europe.


Citation...

Grasgruber et al., The role of nutrition and genetics as key determinants of the positive height trend, Economics & Human Biology, available online 7 August 2014, DOI: 10.1016/j.ehb.2014.07.002

Wednesday, March 26, 2014

The story of R1a: the academics flounder on


There's been a lot of horseshit published over the years about Y-chromosome haplogroup R1a, which just happens to be my haplogroup. That includes academic papers in journals like PLoS ONE and Nature. My advice is, take all of that stuff with a very large pinch of salt and just look here for updates.

Indeed, a new paper on the phylogeography of R1a appeared at the Nature website today: Underhill et al. 2014. It's actually a much better effort than anything else on the topic at academic level thus far, but certainly not without issues.

For instance, the authors failed to include two well known and very important R1a subclades in their analysis: the Northwest European-specific R1a-CTS4385 and the East and Central European-specific R1a-Z280. As a result, the former is lumped with R1a-M417* and the latter with R1a-Z282*. In fact, Z280 is shown to be above Z282 in the topology of R1a-M420 (see Figure 1 here), which is plain wrong. These are major oversights and mean that this study is not a very useful resource as far as the phylogeography of European R1a is concerned.

But the paper does show a couple of interesting things. For instance, the maps below offer the best illustration to date of the dichotomy between the European-specific R1a-Z282 and Asian-specific R1a-Z93.



However, these are very closely related subclades, sharing the Z645 mutation (unfortunately not mentioned in the paper), and both reaching high frequencies among Indo-European speakers. It's therefore plausible that groups carrying these markers expanded to the west and east from a zone between their current hotspots, possibly the Volga-Ural region, rather recently.

These migrations had to have happened after 4800-6800 YBP, which is the age of R1a-M417 reported by Underhill et al., and backed up by estimates from genetic genealogists using, among other things, complete R1a sequences (see here). In other words, the rapid expansions of R1a-Z282 and R1a-Z93 appear to have taken place from more or less the same region during the generally accepted early Indo-European timeframe, making them excellent candidates for paternal markers of the early Indo-European dispersals.

At the same time, the paucity of R1a-Z93 and derived lineages in Europe, including Eastern Europe, suggests that historic migrations originating in East and Central Asia, like those of the early Turks, had a negligible effect on the paternal ancestry of modern Europeans. This shows very clearly on the PCA in Figure 4 (see here).

Citation...

Underhill et al., The phylogenetic and geographic structure of Y-chromosome haplogroup R1a, European Journal of Human Genetics, advance online publication, 26 March 2014; doi:10.1038/ejhg.2014.50

See also...

The beast among Y-haplogroups

Sunday, February 23, 2014

Genetic affinities of Estonian Poles


The Estonian Biocentre has a new genotype dataset available from the recently released "Khazar" preprint (see here). The samples include Poles from Estonia, so I ran a PCA to see whether there was a clear difference between them and their ethnic kin from Poland in terms of genome-wide genetic structure. This doesn't appear to be the case, except for a few individuals who probably have significant Estonian and/or northwest Russian ancestry. It's an interesting result, considering that, as far as I know, most Estonian Poles are not of recent Polish origin, but have roots in the East Baltic dating back to the Polish-ruled Duchy of Livonia of the 1600s. Please note, the plots were rotated and stretched horizontally to fit with geography.


Citation...

Behar, Doron M.; Metspalu, Mait; Baran, Yael; Kopelman, Naama M.; Yunusbayev, Bayazit; Gladstein, Ariella; Tzur, Shay; Sahakyan, Havhannes; Bahmanimehr, Ardeshir; Yepiskoposyan, Levon; Tambets, Kristiina; Khusnutdinova, Elza K.; Kusniarevich, Aljona; Balanovsky, Oleg; Balanovsky, Elena; Kovacevic, Lejla; Marjanovic, Damir; Mihailov, Evelin; Kouvatsi, Anastasia; Traintaphyllidis, Costas; King, Roy J.; Semino, Ornella; Torroni, Anotonio; Hammer, Michael F.; Metspalu, Ene; Skorecki, Karl; Rosset, Saharon; Halperin, Eran; Villems, Richard; and Rosenberg, Noah A., No Evidence from Genome-Wide Data of a Khazar Origin for the Ashkenazi Jews (2013). Human Biology Open Access Pre-Prints. Paper 41.

Monday, January 27, 2014

Poles more indigenous to Europe than Germans


This has actually been obvious for a while now, thanks to both modern and ancient DNA. But the figure below from the new Olalde et al. paper on the complete genome of a Mesolithic hunter-gatherer from Iberia illustrates it more effectively than anything else I've seen to date. Note that the Polish reference set (PL) shows significantly higher allele sharing with the ancient Iberian, La Brana 1, than do Germans (DE). In fact, only Swedes (SE) manage to better Poles in this regard. But it's also worth noting that Poles show the highest allele sharing with the two partial genomic sequences of Neolithic hunter-gatherers from Gotland, Ajv70 and Ajv52.


On the other hand, compared to Poles, Germans clearly show higher allele sharing with Gok4, the Neolithic farmer from Southern Sweden, and Otzi the Iceman from the Copper Age Tyrolean Alps. Unlike the hunter-gatherers, who are genetically more Northern European than any Europeans alive today, these ancient samples are more Mediterranean, and indeed more Near Eastern, than most present-day Europeans, which is something that can be seen clearly on the main Principal Component Analysis (PCA) from Olalde et al. below. This suggests that most of their ancestors arrived in Europe from the Near East during the Neolithic.


This intriguing outcome is perhaps best explained by geography and climate? Germany is situated west of Poland, so it has a warmer climate, and thus its territory was more heavily settled by early farmers from the Mediterranean Basin during the Neolithic. Moreover, much of what is now Germany was part of the Roman Empire, which might have facilitated gene flow between the ancestors of present-day Germans and southern Europeans.

Poles, on the other hand, show stronger genetic links to Baltic populations, especially Lithuanians and Estonians, who are arguably the most Mesolithic-like Europeans alive today (see here). In fact, if they were present on the graphs above, they'd probably easily top the allele-sharing list with La Brana 1 and all of the hunter-gatherers from Gotland. This might be due to the almost impenetrable primeval forests that once covered the areas just south and east of the Baltic, as well as the relatively cold climate in these regions.

Citation...

Olalde et al., Derived immune and ancestral pigmentation alleles in a 7,000-year-old Mesolithic European, Nature (2014), doi:10.1038/nature12960

See also...

The really old Europe is mostly in Eastern Europe

Mesolithic genome from Spain reveals markers for blue eyes, dark skin and Y-haplogroup C6