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Saturday, November 12, 2011

Origins of R1a1a in or near Europe (aka. R1a1a out of India theory looks like a dud)


Ten years ago Passarino et al. released a paper focusing on the origins and spread of R1a1a (back then known as Eu19). They did this by studying the frequency and diversity of the 49a,f/TaqI haplotype 11, which appeared to be linked to R1a1a. The conclusion was that R1a1a most likely originated in present day Ukraine, and expanded from there into Europe and Asia.

However, a couple years later, STR diversity became the method of choice for studying Y-DNA haplogroup origins and expansions, and the information provided by 49a,f/TaqI Ht11 was basically ignored.


Despite lots of quirky results since then, like placing the ancestors of some modern populations far in Northern Europe when it was still covered with massive ice sheets, no one in academia attempted to challenge the new methodology until this year (see here). However, in the meantime, it was "discovered" that India harbored the greatest diversity in R1a1a STRs, and was thus hailed as the place of origin of this widespread paternal marker.

It seems we've now come full circle, because latest work on the SNP structure within R1a1a shows that India has very low R1a1a diversity. For instance, all Indians tested to date for newly discovered R1a1a SNPs, mostly as part of various private Y-DNA projects, have come back positive for the Z93 mutation. This marker is not upstream to any European R1a1a subclades. In fact, most Eastern Europeans tested to date have come back ancestral for Z93. This information gels very well with ancient DNA results, which show a movement of light-pigmented European-like groups deep into Asia during the early metal ages from somewhere in West Eurasia (see here).

The news just in, courtesy of the R1a and Subclades Y-DNA Project, is that the
Z283 SNP ties together the three major European R1a1a subclades. These are R1a1a1-Z284, largely found in Scandinavia, R1a1a1-M458, characteristic of Western Slavic and Eastern German populations, and R1a1a1-Z280, of Central and Eastern Europe. The primary distribution of Z283 shows an uncanny resemblance to that of the former Corded Ware cultural horizon of Northern Europe. Below is a map of the Corded Ware zone from Haak et al. 2008, which describes the discovery of R1a1a in the ancient remains from a Corded Ware burial in what is now Eastern Germany.



References...

Passarino et al., The 49a,f haplotype 11 is a new marker of the EU19 lineage that traces migrations from northern regions of the black sea, Human Immunology, Volume 62, Issue 11, November 2001, Pages 1313-1314

FTDNA R1a and Subclades Y-DNA Project

Haak et al., Ancient DNA, Strontium isotopes, and osteological analyses shed light on social and kinship organization of the Later Stone Age, PNAS November 25, 2008 vol. 105 no. 47 18226-18231


Friday, October 28, 2011

Dienekes attempts to strike back...and trips up again


I just read Dienekes' retort to my criticism of his work. Hilarious stuff...

Actually, according to the PCA plot of the Yunusbayev et al. (2011) paper, they are transitional, being situated toward both the Balkans and the Caucasus, relative to Belorussians/Lithuanians, i.e., the populations that generally show peaks of East European-related components. This is also supported by the ADMIXTURE analysis that reveals Ukrainians to possess a Caucasus-centered component largely lacking in other Eastern Slavs, but shared with Balkan/Caucasus populations.

First of all, the problem with his analysis was that Ukrainians showed higher "West European" and lower "East European" than Poles. So Ukrainians were more "western" because they're more southern and eastern? What about the factor that Poles are really more western? Shouldn't that negate the pseudo-western character of the Ukrainians?

He's not making any sense at all. Simply, he's got a hybrid unsupervised/supervised spreadsheet up, and the results don't gel. In other words, they're not directly comparable between the two sets of samples, at least in some cases anyway. Why can't he put up a note that this is an issue and separate the two sets of samples in the spreadsheet?

To make matters worse, Eurogenes suggests that my euro7 analysis agrees with his K=10 which was presented two weeks later. So, apparently, I am posting correct information about Ukrainians 2 weeks before he does, and this means that I am turning around to his way of thinking rather than vice versa. Go figure.


It doesn't matter what came first. What matters is that some of the results he's posting, like those from the euro7 analysis, seem to be correct, and correlate with my own work, while some don't. The latter have to be taken down or corrected.

Eurogenes continues with his posting of supposed MDS/PCA plots supporting his thesis. Actually, what he has posted are plots based on metric distances in the space of admixture proportions; these are not genetic distances because e.g., a +/- 1% difference in a Sub-Saharan component results in the same Euclidean distance difference as a +/-1% in a European one, although the former affects genetic distance much more strongly than the latter. Metric distances are fine to quickly determine closeness of samples in the space of admixture proportions, but they are certainly no substitute for real genetic distances.

My thoughts exactly. That's why
the MDS plots I posted were based on raw SNP data, and not on metric distances in the space of admixture proportions. The reason I also posted the PCA plots, which were indeed based on the admixture proportions, was because, as he says, "metric distances are fine to quickly determine closeness of samples in the space of admixture proportions".

I am also, apparently, accused of neglecting to point out the deficiencies of Dodecad v3, and I am invited by Eurogenes to retract it completely! This proposal is equivalent to the idea that we should burn old topographic maps that were based on measurements with sticks, ropes, and trigonometers, because we can now measure distances with laser beams. And, it is funny indeed that I am supposedly neglecting the deficiencies of Dodecad v3 when, 3 weeks before the Eurogenes rant, I post exactly what its limitations are, and how it can be made better.

I haven't been able to find anything on his blog that explains the limitations of the hybrid unsupervised/supervised system. If not presented in their proper context, many of the results obtained via this system are simply erroneous.

It is unfortunate that Eurogenes has chosen to go down that path. Envy is not a good guide to behavior, and perhaps, instead of relishing at the prospect of putting others down, he could spend a little more time inventing something of his own.

It's unfortunate that Dienekes is so aggressive and arrogant when someone tries to alert him to problems or potential problems. Keep in mind, I first raised these issues via a few short comments at his blog, and never intended to write whole articles on the subject. However, his reaction to my posts changed my mind very quickly.


Wednesday, October 19, 2011

Erroneous results from Dodecad (aka. Dienekes)


A while back, Dienekes welcomed "peer review" of his work, which I thought was very commendable. I recently spotted a serious error in his analysis, and let him know about it over at his blog. I was hoping to see a correction, and also an admission that his methodology was faulty. Unfortunately, this hasn't happened to date, so I thought I'd describe the problem in detail here.

In the blog entry Yunusbayev et al. (2011) data assessed with Dodecad v3, Dienekes analyzed samples with ADMIXTURE in "supervised" mode using allele frequencies obtained from a run that didn't include these samples. He posted the results in a spreadsheet, which can bee accessed here.

Obviously, my area of interest is the genetic ancestry of Poles, other Balto-Slavs, and nearby populations. So it only took me a matter of seconds to notice that something was off about the results for several of these groups. For instance, Poles are listed in the spreadsheet as 34.5% West European, and 44.3% East European. On the other hand, the more easterly Ukrainians show 38.5% West European, and only 31.5% East European. Also, the Mordvinian sample from near the Volga scores 38.1% West European, and only 32.5% East European.

The first port of call when checking the validity of such results is to see whether they gel with geography. Clearly these results don't. So either something isn't right, or there are factors that work against the general rule of genes = geography. When I alerted Dienekes of these seemingly implausible figures, he was in favor of the second scenario. His reply was as follows:

Ukrainians' higher West/east European ratio makes perfect sense as it is transitional to both the Caucasus (where there are even higher such ratios) and to the Balkans. Their ratio is exactly what one might expect from their geographical position vis a vis. Russians, Belorussians, and Balts, ie. , populations with a high E/W ratio.

Mordvins are also in line with other Uralic populations (Finns, Selkups) in having an inverted European ratio relative to Balto-Slavs.

Err...no, the results don't make perfect sense. They make no sense at all. There's no way these Ukrainians can be described as transitional to the Balkans and the Caucasus compared to Poles, even if the term is used very loosely. Below are two MDS plots. The first one shows that the same Ukrainians (UA) used by Dienekes do not cluster closer to the Balkans than Poles do (PL), and only barely closer, on average, than the Belorussians. The second plot shows that Ukrainians (UA), Poles (PL) and Belorussians (BY) are all about the same distance from the Caucasus.





In theory, it's possible to argue that the plots above produced different results to Dienekes' analysis because they used only the two most significant dimensions of genetic variation. On the other hand, ADMIXTURE works in a very different way, and so can reveal details past the first two dimensions. But that would be a stretch, because generally speaking, when a population appears to be transitional between two others in an ADMIXTURE run, such results are often very easily reproduced with MDS/PCA plots.

Moreover, I've actually analyzed the same and similar samples with ADMIXTURE and have been unable to reproduce Dienekes' results. In other words, as per geography, Ukrainians are less Western European than Poles, and more Eastern European. This shows up in my latest Eurasian K=10 run (see here), where, on the balance of all the components, the Ukrainians and Mordvinians are more Eastern than Poles.

Below are two PCAs, the first one shows the bizarre results produced using data from Denekes' spreadsheet, with Mordvinians clustering with Ukrainians and Hungarians along Component 1. The result is more reliable along Component 2, because that seems to be picking up North Eurasian admixture in the Mordvinians and Russians, which is much lower in Hungarians, Poles ad Belorussians. The second plot is based on my K=10, and shows a more expected result all round, with the Mordvinians lining up with both Russian samples (RU and North Russian) along Component 1, and also very close to the North Russians along Component 2. They also cluster with the same North Russians in Yunusbayev et al., rather than with the Ukrainians.


A whole range of PCA plots can be produced using the data from the supervised Dodecad V3 and my Eurasian K=10, in which the former results look at least a little out of whack with reality, while the latter appear as expected.

Interestingly, Dienekes' new
euro7 analysis supports the results obtained by me. In this experiment, the same Ukrainians and Mordvinians were used in the initial run that set up the clusters, and came out amongst the most Northeastern European and least Northwestern + Southwestern European samples on the sheet. Now that makes perfect sense.

So what happened? Are these euro7 components different enough to make the results better match geography? Yes, they're a lot more in tune with reality due to a higher quality dataset, with more samples from key areas of Europe and Caucasus. However, it's also clear that the supervised analysis produced erroneous results. It's obvious that it's not always possible to correctly analyze samples with allele frequencies from ADMIXTURE runs in which they were not included, especially versus those that were.

Now that the sampling is better, Dienekes' euro7 shows the previously mentioned Uralic Selkups to have a higher level of membership in the cluster that peaks in Balto-Slavs, than in those which peak in Northwestern and Southwestern Europeans. This is obviously a turn-around from his Dodecad V3 result. So which is correct? Strictly speaking, they're both correct, because the components that form in ADMIXTURE runs are dependent on the allele frequencies in the dataset used, and the number of K (clusters) set by the user. These clusters might peak in different groups depending on the dataset, but the results will usually make pretty good sense in relative terms. Indeed, on the balance of their overall results, across all the ancestral components in the V3 and euro7, the Selkups don't appear very different. They cluster in generally the same area relative to the other samples. See, for instance, their positions on two PCAs based on the V3 and euro7. So unlike the supervised results, it's not possible to outright declare the unsupervised Dodecad V3 results as erroneous.

However, I would say that the appearance of such a dominant Western European-based cluster as seen in the V3 is, at the very least, surprising. For instance, why would the Siberian Selkups carry more allele frequencies that appear Western European than Eastern European? The Uralic theory proposed by Dienekes really doesn't seem plausible. I don't know how many times Dienekes repeated his experiment to see if the results were stable, but scientists often run their experiments as many as 100 times each, and then publish the most consistent results.

If Dienekes obtained those results from multiple runs, and it was a stable effort, then that's fine. However, the Western European-based cluster still looks unusual enough to treat it with great caution. Suffice to say that it's not something that can be reliably used to theorize about the peopling of Europe, or the genetic ancestry of linguistic groups, like the Uralics. Dienekes did this, which I thought was very naive of him. But it was even more naive of many people to take his musings seriously. I don't believe that he'll ever be able to produce similar results with his updated dataset (like the higher West/East European ratio in the Ukrainians, Mordvinians and Selkups).

Obviously, there's nothing wrong with experimentation. That's what science and genome blogging are all about. We're not just here to provide a genetic ancestry service, but also to try and unravel mysteries that are taking scientists years to get around to via the convoluted peer review system in journals. Mistakes will happen, because boundaries are being pushed, but these mistakes have to be corrected.

Update: Dienekes attempts to strike back...and trips up again


Monday, October 17, 2011

Pigmentation genetics of Europeans


The maps below are based on three genome-wide SNPs showing high correlation with blue and green eyes and/or fair hair in Europeans. The results obviously suggest that there's an increase in hair and eye blondism from south to north in Europe, with clear peaks east of the Baltic Sea. The three SNPs are rs1667394 (HERC2 gene), rs12913832 (OCA2 gene), and rs12896399 (SLC24A4 gene).





Indeed, I'm a bit taken aback by the very high rate of suggested blondism among the Belorussians and Mordvinians (second highest dot in Russia). This might have something to do with sampling bias. Perhaps most of the 12 Belorussians and 16 Mordvinians used here came from fairer than average communities within their respective nations? I have no idea. In any case, I don't think the picture is too far from reality, because multiple sampling sites from the same general biogeographic zones, but several hundred kilometers apart, are showing very similar results. This can't be a coincidence.

It's also interesting to note that the East Baltic peak in blondism genotypes correlates closely with the North + East European genome-wide ancestral component in my latest ADMIXTURE experiment (see here). Perhaps this is where natural selection for these traits was most extreme due to very specific environmental pressures, like lack of sunlight? Maybe this is also where these traits spread from, either gradually or during one or several major migrations? Someone should look into that. Meantime, I'll try and update this post with new maps as more samples come in.

Friday, October 7, 2011

European admixture among ancient East Asians (two-rooted canines carried by early Indo-Europeans to China)


Two-rooted lower canines are rare in humans, but they are most commonly found among Europeans, at levels of up to 9%. A new study reveals that this trait reached unusually high frequencies in ancient groups from East Central and East Asia, particularly those of Afanasevo, Scythian, Uighur and Ordos origin (2.8% to 4%). This is a strong indication that such groups carried significant European ancestry, and were possibly the descendants of the same European migrants who took R1a1a and Indo-European culture deep into Asia after the Neolithic (see here).

In Table 1, the population variation of two-rooted lower canines is shown for major populations of the world. To emphasize the point that this is a European trait, of the 12,128 individuals included in the table, only 306 express two-rooted lower canines (2.5%) but of these 83% (254) were Europeans. If you include related Asiatic Indian, Middle Eastern, and North African populations, this number increases to 89% (272/306).

...

The presence of the two-rooted canines in East Asia may provide some clue as to the eastward migration of new populations into China and Mongolia. The largest numbers of individuals with this trait are concentrated along the western and northern frontiers of China and Mongolia. Archaeological excavations support the large scale movement of people into this area during the Bronze age (ca. 2200 BCE–400 BCE). Burial artifacts and settlement patterns suggest cultural and technological ties to the Afanasevo culture in Siberia, which in turn is linked archaeologically, linguistically, and genetically with the Indo-European Tocharian populations that appear to have migrated to the Tarim Basin ca. 4,000 years ago (Ma and Sun, 1992; Ma and Wang, 1992; Mallory and Mair, 2000; Romgard, 2008; Keyser et al., 2009; Li et al., 2010).


Christine Lee and G. Richard Scott, Brief Communication: Two-Rooted Lower Canines - A European Trait and Sensitive Indicator of Admixture Across Eurasia, American Journal of Physical Anthropology (2011), DOI: 10.1002/ajpa.21585


Wednesday, September 14, 2011

Sharp genetic discontinuity between Eastern Europe and the Caucasus


The rather artistic PCA below shows genetic clines that run through West Eurasia. It basically suggests that Europe and the Caucasus were populated by similar populations from the Near East, but didn't mix much after that. There appears to be some Russian influence among a few samples from the Caucasus, but no significant admixture from the Caucasus in Ukraine or Russia.


The Caucasus, inhabited by modern humans since the Early Upper Paleolithic and known for its linguistic diversity, is considered to be important for understanding human dispersals and genetic diversity in Eurasia. We report a synthesis of autosomal, Y chromosome and mitochondrial DNA (mtDNA) variation in populations from all major subregions and linguistic phyla of the area. Autosomal genome variation in the Caucasus reveals significant genetic uniformity among its ethnically and linguistically diverse populations, and is consistent with predominantly Near/Middle Eastern origin of the Caucasians, with minor external impacts. In contrast to autosomal and mtDNA variation, signals of regional Y chromosome founder effects distinguish the eastern from western North Caucasians. Genetic discontinuity between the North Caucasus and the East European Plain contrasts with continuity through Anatolia and the Balkans, suggesting major routes of ancient gene flows and admixture.

Bayazit Yunusbayev et al., The Caucasus as an asymmetric semipermeable barrier to ancient human migrations, Mol Biol Evol (2011) doi: 10.1093/molbev/msr221 First published online: September 13, 2011


Monday, September 5, 2011

Surprising aDNA results from Neolithic and Bronze Age Ukraine


Update 16/09/2013: The full thesis is now available to the public (see here).

...

A thesis abstract published at the Grand Valley State University website reports that six out of seventeen ancient samples from Neolithic and Bronze Age Ukraine belonged to Siberian-specific mtDNA haplogroup C (see here). This looks like a very important outcome, because it suggests that East Eurasian mtDNA lineages were fairly common in pre-Indo-European Ukraine. However, they weren't found among Bronze Age Corded Ware remains from eastern Germany, with supposed origins on the Eastern Europe steppe (see here), nor are they commonly found in present-day Ukraine. So perhaps the Eastern European steppe was not the source of any large-scale migrations into Central Europe, including the Corded Ware expansions? Instead, maybe the European steppe populations were replaced by successive waves of migrants from East Central or even Central Europe? Here's the abstract, which is all that's available at the moment:


Studies of mitochondrial DNA (mtDNA) polymorphism have provided valuable insights for understanding patterns of human migration and interaction. The ability to recover ancient mtDNA sequence data from post-mortem bone and tissue samples allows us to view snapshots of historic gene pools firsthand, provided that great care is taken to prevent sample contamination. In this study, we analyzed the DNA sequence of the first hypervariable segment (HVSI) of the mtDNA control region, as well as a portion of the coding region, in 14 individuals from three collective burials from the Neolithic Dnieper-Donetz culture and three individuals from Bronze Age Kurgan burials, all located in modern-day Ukraine on the northern shores of the Black Sea (the North Pontic Region, or NPR). While most of our samples possessed mtDNA haplotypes that can be linked to European and Near Eastern populations, three Neolithic and all three Bronze Age individuals belonged to mtDNA haplogroup C, which is common in East Eurasian, particularly South Siberian, populations but exceedingly rare in Europe. Phylogeographic network analysis revealed that our samples are located at or near the ancestral node for haplogroup C and that derived lineages branching from the Neolithic samples were present in Bronze Age Kurgans. In light of the numerous examples of mtDNA admixture that can be found in both Europe and Siberia, it appears that the NPR and South Siberia are located at opposite ends of a genetic continuum established at some point prior to the Neolithic. This migration corridor may have been established during the Last Glacial Maximum due to extensive glaciation in northern Eurasia and a consequent aridization of western Asia. This implies the demographic history for the European gene pool is more complex than previously considered and also has significant implications regarding the origin of Kurgan populations.

Newton, Jeremy R., "Ancient Mitochondrial DNA From Pre-historic Southeastern Europe: The Presence of East Eurasian Haplogroups Provides Evidence of Interactions with South Siberians Across the Central Asian Steppe Belt" (2011). Masters Theses. Paper 5.


Saturday, May 14, 2011

German Sorbs genetically closer to Poles than to Germans...but which Germans?


The conclusion of the authors of this paper on Sorb genetics is that these last Slavic speakers of Germany are closer to Poles than to Germans in terms of overall genetic structure. This is a reasonable conclusion based on the data they analyzed, but the problem is that they didn't analyze any German samples sourced specifically from near the Sorb homeland (ie. eastern Germany). So this paper probably has things right, but no one can really say for sure. It's good to see that the authors are aware of this issue...

One caution regarding our results is that the geographical origins of our reference populations are crudely characterized only by country and thus may not be random samples. If many of the Germans in the POPRES data are western German samples, this may inflate the apparent differences we observe between Germans and Sorbs. The LPZ Germans contained two individuals from Eastern Germany who do appear closer to the Sorbs, suggesting that population structure within countries is a valid concern. Certainly, a tighter and denser sampling of German, Polish and Czech individuals from regions surrounding the Sorbian territories would be ideal for confirming or refuting the results found in this study.

Just in case there's a re-run being planned, please remember that the Poles living close to the Sorbs are actually of eastern Polish origin, from the former Polish territories in Belarus and Ukraine. It would be better to sample western Poles living in areas that belonged to Poland prior to the Second World War.


Krishna R Veeramah et al., Genetic variation in the Sorbs of eastern Germany in the context of broader European genetic diversity, European Journal of Human Genetics advance online publication 11 May 2011; doi: 10.1038/ejhg.2011.65

Tuesday, March 22, 2011

Reconstructing the Ancestral North Indian (ANI) genome


Back in 2009, Reich et al. theorized that the current South Asian gene pool was basically made up of two founding genetic components; Ancestral North Indian (ANI), and Ancestral South Indian (ASI). The distilled ANI, they noted, was more similar to the genomes of modern Northwest Europeans than those of the Adygei from the Caucasus. This is obviously out of whack with geography, but it does make sense based on what I've seen in my experiments on the Pakistani samples from the HGDP. Many of them, especially the Pathans, carry numerous segments, or haploblocks, that basically look North European. This gave me an idea to try and reconstruct the ANI genome based on such fragments. The first chromosome of my composite sample, which I call the "ANI composite" is available for download here. It's a PLINK Ped file in illumina AB format with 19,261 SNPs.

Below are several PCA plots featuring the "ANI composite", obviously not including the HGDP samples used to make it (see below). Overall, it seems to resemble most closely my reference samples from Eastern Europe. I have to admit that I was very pleased to see it behaving like a set of genotypes from a real human subject across many dimensions of genetic variation. PCA are very sensitive to anomalies, such as unusually long runs of homozygosity, so the fact that my composite can pass for a normal sample on these plots is fantastic.








So how did I do this? Well, it wasn't very difficult, but a bit tedious, so I need a break before continuing. I used information from my earlier experiments with ADMIXMAP, HAPMIX and RHH Counter to locate and delineate North European-like segments in phased Pakistani HGDP samples. I phased the data myself with BEAGLE, in a pool of South Asian and Middle Eastern samples, so as not to bias the results of phasing and imputation towards Northern Europe. In order to keep the alleles in phase when loaded into PLINK, I duplicated the haplotypes, producing completely homozygous individuals out of each one. Then I created an ANI composite dummy with 100% no calls, and loaded the haplotypes into this sample with a Python script. The first to load were the Pathan haplotypes, followed by the Burusho. I chose individuals from these two groups to make up the backbone of the putative ANI genome because they always seem to come out most "North European" in my ADMIXTURE and PCA/MDS runs compared to other South Asians. The empty spaces were filled with haplotypes from the Brahui and Balochi. Below is a list of all the samples used:

Pathan HGDP00213
Pathan HGDP00214
Pathan HGDP00218
Pathan HGDP00224
Pathan HGDP00241
Pathan HGDP00243
Pathan HGDP00254
Pathan HGDP00258
Pathan HGDP00259
Pathan HGDP00262
Pathan HGDP00264

Burusho HGDP00338
Burusho HGDP00356
Burusho HGDP00364
Burusho HGDP00382
Burusho HGDP00392
Burusho HGDP00412
Burusho HGDP00417
Burusho HGDP00423
Burusho HGDP00428
Burusho HGDP00433

Brahui HGDP00007
Brahui HGDP00009
Brahui HGDP00017
Brahui HGDP00041
Brahui HGDP00047

Balochi HGDP00054
Balochi HGDP00058
Balochi HGDP00062
Balochi HGDP00072


The phased data and the "ANI" haplotypes used in this experiment are available on request from eurogenesblog [at] hotmail [dot] com. I welcome feedback and suggestions on how to improve my methodology. Admittedly, this was a test run, so it's unlikely to be perfect.


Saturday, February 19, 2011

"Slavic" R1a1a7 from medieval east Germany


Update: 30/06/2013: Anthropological and genetic investigation of a medieval Slavic community from Usedom, east Germany

...

The abstract below comes from a thesis on a 12th to 13th century burial ground in Mecklenburg-Vorpommern. Physical anthropology wasn't much use in helping to figure out whether the skeletons from this site were German, Danish or Slavic. However, one of the samples belonged to West Slavic-specific Y-chromosome haplogroup R1a1a7, which certainly upped the chances of this community being at least partly of Slavic origin.

This study investigates 200 skeletons from an early Christian graveyard of the 12th to early 13th century in Usedom (Mecklenburg-Vorpommern, Germany). The city of Usedom was a notable maritime place of trade in a time of major political and social transformations. The Christianisation of the Slavic elite in 1128, the following raids of the Danes and the influx of German settlers starting in the 13th century were formative events.

The reconstruction of the living conditions of the Usedom population was achieved by means of well established anthropological and palaeodemographical methods. Age and sex distribution comply with other ordinary populations of that time frame: high proportion of children (32 %), comparatively few adolescents but many adults (59 %) as well as a slight surplus in men. Remarkably, a deficit in women in the mature age class is attended by an increased mortality of girls of the age class infans I. However, this may be due to a methodical error.

In order to clarify a possible Slavic, Danish or German background of the inhabitants of Usedom, eight skull measures, four skull indices and five measures of the long bones of the extremities were investigated typologically as well as statistically on the basis of their arithmetic means and compared to the measures of two series of Slavic or multiethnic/place of trade background (Sanzkow and Haithabu, respectively). The comparison of arithmetic means did yield statistically significant differences between the three populations. The men and women of Usedom seem to be more closely related to the Sanzkow population. However, they appear to take a position between the two other populations.
Unfortunately, a comparison with Slavic and Germanic populations of the Neolithic till Early Middle Ages did not provide distinct results. The archaeologically based assumption of a mainly Slavic population cannot be rejected with anthropological means.

The analysis of mitochondrial and Y-chromosomal DNA, however, generated auspicious results despite adverse storage conditions. Results could be obtained from all four samples. Two individuals were of mtDNA haplogroup H and two of haplogroup K.
Y-chromosome analysis yielded haplogroups E1b1b and R1a1a7, respectively, in two males. Future molecular research will see improved methods for the even more detailed reconstruction of human migration.

Janine Freder, Die mittelalterlichen Skelette von Usedom - Anthropologische Bearbeitung unter besonderer Ber├╝cksichtigung des ethnischen Hintergrundes, Doctoral thesis, 2010, Freie Universitat, Berlin, Department of Biology, Chemistry and Pharmacy