Dutch: single or dual population?

31 May
A recent study deals with the autosomal structure (or lack of it) of the population of the Netherlands.
Oscar Lao et al., Clinal distribution of human genomic diversity across the Netherlands despite archaeological evidence for genetic discontinuities in Dutch population history. Investigative Genetics 2013. Open accessLINK [doi:10.1186/2041-2223-4-9]
They studied the autosomal DNA of almost 1000 anonymous male donors from the Netherlands. Interestingly the lowest cross-validation value was at K=1, what indicates that the Dutch (Frisians included) are a very homogeneous population, that the most accurate result of their splitting into several components produced only one such component.

Supp. fig. 3-A

K=2 and K=3 however produce similarly low scores, however the researchers preferred to study K=5, which makes a shallow valley between its neighboring values. Probably not the best idea but nevertheless the overall result is similar to what they get at K=3.

Supp. Fig. 3b (ADMIXTURE clustering)

K=2 is very intriguing because only a few scattered individuals fall totally (just two) or partly within the second cluster. These individuals persist in their distinctiveness through the whole series. I wonder if they are people with non-European ancestry (no way to know because they are anonymous donors and as far as I could discern ancestry information was not requested from them).
K=3 is what I would consider the most usable K-level, with similar cross-validation score to the lowest one (K=1) and displaying two widely represented clusters (plus the anomalous one mentioned before). However the authors preferred to work on K=5, which, luckily enough, is quite similar to K=3 in the essentials, also showing two basic components (yellow and pink):

Figure 4 Admixture analysis of the Dutch samples. A) Pie chart map of the genome-wide ancestry assignment in the 54 Dutch subpopulations estimated with 10 independent runs by ADMIXTURE [26] using K = 5 assumed parental populations. B) Individual ancestry estimated by ADMIXTURE using K = 5. C) Ternary plot of subpopulations using the three.

If we ignore the ubiquitous orange component and the minor ones, we can appreciate that the country has two distinct areas:
  1. Southern area (dominated by the pink component): including Zeeland, North Brabant, Limburg, South Holland, much of North Holland and, counterintuively, Western Overjissel.
  2. Northern area (dominated by the yellow component): including Friesland, Gröningen, Drenthe and the eastern areas of Gelderland and Overjissel.
  3. Transitional area: Utrecht and parts of Gelderland and North Holland.

Frisian language today
(CC by ArnoldPlaton)
The authors go to great lengths to try to explain this structure but they do not seem to reach any strong conclusion. I’m not any expert in Dutch history but a tentative explanation may be that, roughly, the yellow-dominated areas correspond more strongly to the areas of Low German/Frisian presence and/or some of their prehistoric precursors (often prehistoric cultures of Low Germany tended to be distinct to those further South).

Low Saxon area (NL)
(CC by Gebruker:Grönneger 1)
While Dutch and the related Limburgish dialect are part of the wider Low Franconian category (descending from Frankish Germanic and historically spoken around the Rhine), most of the yellow-dominated regions belong to distinct historical language areas: Frisian and Low German, which are both believed to derive (together with English) from the same ancestral Ingaevonic branch of West Germanic. This historical and prehistorical duality may well explain the modern genetic duality in its fundamentals, if not the genetic boundary in detail.

Your take in any case.

Approx. Germanic dialectal areas some 2000 years ago
Red: North Sea Germanic (Ingaevonic)
Orange: Wesser-Rhine Germanic (Istvaeonic)
full legend
(CC by Hayden120)


8 responses to “Dutch: single or dual population?

  1. Davidski

    May 31, 2013 at 10:21 am

    There weren't any Germanics in Poland until the Middle Ages. We know this because Germanics didn't eat millet.

  2. Maju

    May 31, 2013 at 10:45 am

    Well, it's interesting but I doubt that's any sort of "smoking gun". Goths left a legacy of some written texts which are clearly a Germanic dialect. All them were considered "Germans" in Antiquity and Early Middle Ages. most historians are willing to assume AFAIK that they were just a passerby elite, much like Varangians in Russia or the very same Goths in Italy and Spain (as well as other Germanic ruling elites, none of which left a major long-lasting linguistic legacy, with the English exception). I don't take the map as implying that all the shaded areas were monolingual in said dialects but that those languages were spoken in those areas by at least some people.

  3. Davidski

    May 31, 2013 at 1:14 pm

    There aren't any Gothic archeological remains from Poland – no Gothic texts or even any pre-Viking items with runes. You must be thinking of what is now Ukraine.Poland has the Wielbark and Przeworsk cultures, which are often described as Gothic and Vandal, but their remains are identical to those of Medieval Slavs in terms of cranial and odontological traits. Also, as per above, Wielbark remains showed consumption of millet, which wasn't consumed in Scandinavia, or even by likely Scandinavian Vikings stationed in Poland.It seems Goths weren't present in Poland. They probably moved into Ukraine south of the Carpathians.

  4. Maju

    May 31, 2013 at 1:58 pm

    The Gothic text, a partial translation of the Bible is from Italy. Whether there were Goths in what is now Poland before their arrival to Ukraine and Romania or not is a debate I don't feel qualified to enter into but it is what I have read once and again in many history books."… the Wielbark and Przeworsk cultures, which are often described as Gothic and Vandal, but their remains are identical to those of Medieval Slavs in terms of cranial and odontological traits".I would not be able to distinguish a Goth from a Pole either most probably. Europeans are all very similar and even more so Northern-Central Europeans. "Also, as per above, Wielbark remains showed consumption of millet, which wasn't consumed in Scandinavia"…So? People change dietary habits. "When in Rome do as Romans do"."Scandinavian Vikings stationed in Poland".In quasi-isolated coastal enclaves, not the same thing. "They probably moved into Ukraine south of the Carpathians".Directly from Sweden? Maybe flying in anachronistic zeppelins? What about the references by several Greco-Roman Geographers of Eastern Germanics (Vandals, Goths, Burgundians)? I know they are imprecise but they don't seem to be talking of Sweden nor Ukraine but of the northern reaches of Central Europe. Romans were quite familiar with all that area, having briefly conquered Germany up to the Elbe and being always in need to defend against ravaging Germanic tribes attempting often to cross the limes. Where do you think the Goths lived at before reaching Ukraine, when Ptolomy and the rest described them?Per Wikpedia, Wielbark culture… was influenced by southern Scandinavian culture beginning as early as the late Nordic Bronze Age and early Pre-Roman Iron Age (ca. 1300 – ca. 300 BC).[29] In fact, the Scandinavian influence on Pomerania and today's northern Poland from ca. 1300 BC (period III) and onwards was so considerable that some see the culture of the region as part of the Nordic Bronze Age culture.[30] (…) The settlement in today's Poland may correspond to the introduction of Scandinavian burial traditions, such as the stone circles and the stelae especially common on the island of Gotland and other parts of southern Sweden.In any case, it seems mostly irrelevant to the main topic.

  5. eurologist

    June 1, 2013 at 3:06 pm

    There weren't any Germanics in Poland until the Middle Ages. We know this because Germanics didn't eat millet.I and almost every respectable archaeologist, linguist, and historian strongly disagrees with you, on this point. Sounds more like Polish nationalism. Poland and Slaves in that region did not exist until after ~500 CE, by a huge amount of archaeological and contemporaneous historical data. There is pretty much unequivocal evidence and academic support for that.

  6. Maju

    June 1, 2013 at 5:01 pm

    You seem to be right, Eurologist. However it's very likely that Germanic elites (Goths, Vandals, etc.) ruled over other more locally rooted peoples, who later assimilated into Slavic ethno-linguistic identity. In any case the Eastern Germanic tribes seem all to have stemmed from Scandinavia and ruled over what is now Poland, and later Ukraine and Romania, as elites. For example the very Chernyakov culture that coincides with the first historical Gothic kingdom in Ukraine-Romania is also widely claimed today to be at the origin of historical Slavs, being itself surely a mixture of diverse ethnic backgrounds (proto-Slav, Gothic, Dacian, Sarmatian, etc.)Ethnogenesis is often complex but in the Metal and Middle Ages I tend to imagine it as mostly locally rooted peoples who fell subject of diverse fluctuating tribal-feudal militaristic oligarchies, who, if their rule was long enough, usually assimilated them into the ethnic identity of the elite. In the Middle Ages at least rural workers were at least 90% of the population. Most of these did not migrate. This may well explain the relative stability of the genetic legacy apparent between the Bronze (and maybe Chalcolithic) Age up to present day, in spite of relatively frequent ethnic identity changes.

  7. eurologist

    June 2, 2013 at 2:19 pm

    Maju,I agree with most of that. Clearly, despite everything, the core populations, say, between the Elbe/Saale and Vistula rivers did not change all that much during the past ~4,000 years. I also agree that East-Germanic influence peaked while Slavic expansion got started. Nevertheless, the core population in much of the region remained the same and showed the same superposed West-East cline as 2,000 years before and as today.

  8. eurologist

    June 6, 2013 at 11:54 am

    Maju,Coming back to your original post, I largely agree with your summary statements. Also, I think the orange component corresponds to western Lower Saxon low German vs. Frisian (yellow component).When the previous two Dutch analyses came out, I made the point (elsewhere) that Dutch genetics cannot be understood without also looking at neighboring Germany and Flemish Belgium, since the boundaries are rather arbitrary and relatively recent. In most cases, you see similarities along similar latitudes even on this small scale.On the German side, from north to south, you have: Frisian, Emsland (western Lower Saxony low German), Grafschaft (transition from western Lower Saxony low German to NW Westphalian), mainstream west-Westphalian, northern Lower-Frankish (related to central Dutch), southern Lower-Frankish (related to SE Dutch and extreme N Flamish) and Ripuarian middle-Frankish (related to Flemish).I have traveled the region extensively, and would say that north of the Lippe river I can make out three different types (they are not uniquely present but somewhat representative; they may correspond from N to S to yellow, orange, and turquoise; pink definitely seems to be Frankish and thus more southern on the German side). Approaching the Lippe river and towards the Rhine, things get more complicated and cosmopolitan, which is not surprising given the long presence of Romans and far-traveling merchants, there, and a much more tumultuous history. Still, clearly, SW of the Lippe/Rhine area is Frankish (pink component).W and N Frisians are generally quite tall, lank, with relatively large noses, and disproportionally light blond (yellow component).In the central Emsland you can find people with slightly Baltic features (a bit more stocky, not as tall, more subcutaneous fat, wider faces, more widely spaced and larger eyes, flat, small, broader noses, darker blond to slightly reddish hair: orange component).Towards the southern Emsland and into the Grafschaft and NW Westphalia, you find some rather tall, white-skinned, gracile people with seemingly thin, long bones, now more often curly and dark blond to dark brown hair, flat chests, slightly larger and longer noses, a narrow, sometimes triangular face, and a bit of an androgynous look. You can find the same phenotype all the way to the Flemish regions of NE Belgium (turquoise component?).It would be interesting to see if the three components outside pink are more stratified on the German side than in Holland.


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