A good month ago, I presented here a new publication by Krause-Kyora e.a. “Neolithic and medieval virus genomes reveal complex evolution of Hepatitis B” that includes some interesting fresh aDNA from Central Europe. The most fascinating sample they provide is TRB-Tiefstichkeramik, Hildesheim-Sorsum, 3335–3107 cal BC, which closes an important geographical, chronological and cultural gap, and holds several surprises. Before presenting and discussing that sample, however, let me start with some background information:
What means “TRB-Tiefstichkeramik”?
Most of you will know the “classic” structuring of TRB into North, West, East, South and Southeast Groups as first proposed by J.A. Bakker in 1989. “Tiefstichkeramik” isn’t part of that structure, isn’t it? Well, in fact, it is: The little “A” in Bakker’s map, in-between the N, E, S and W Groups stands for the “Altmark Group” that in German is known as “Altmärkische Tiefstichkeramik“. However, Hildesheim-Sorsum isn’t in the Altmark, but a good 100 km further SW, in an area that would commonly be regarded as southern outskirt of the TRB West Group.
Then, I realised that “Tiefstichkeramik” was traditionally used as alternative label of the TRB West Group. This label is now widely regarded as obsolete, as (i) it only characterises a specific time horizon (ca. 3350-3000 BC) of TRB West, and (ii) “Tiefstich” decoration (“stab-and-drag” in English, partly with white fill) wasn’t just characteristic for the Altmark and TRB West, but between 3500 – 3000 BC also dominated in TRB North, occasionally occured in the S and SE Groups, and, in its final blossoming with the Bernburg Culture, made it as far south as Franconia and Bohemia.
Anybody interested in further details is referred to J.A. Bakker “The TRB West Group: Studies in the Chronology and Geography of the Makers of Hunebeds and Tiefstich Pottery”. That title reveals the main feature of Tiefstich pottery: It is closely linked to the spread of megalithic burials (hunebeds in Dutch). In fact, TRB household pottery used to be rather plain and undecorated. The richly incised beakers were reserved for ritual purposes, and almost all of them were found in megalithic burials. So, unless a Dolmen or chamber grave is fully dismantled to collect organic residue between and below the groundstones for AMS dating, the best method for age determination is still analysis of the (Tiefstich) pottery it contains against fine-tuned regional chronologies (e.g. Brindley I-VII in the Netherlands).
The genesis of Nordic Megalithism is yet somewhat obscure. While the epicentre clearly lies on the Danish Isles, the earliest AMS dates come from the periphery: Borgstedt (n. Rendsburg) ca. 3960 – 3740 calBC, Albersdorf and Lüdelsen 36th cBC, Gökhem 17 3638–3378 calBC, Gotland 3619- –3351 calBC. The earliest safely dated Dolmen on Zealand (Ølstykke) is from the 35th cBC, contemporary with early megalithic burials on the Mecklenburg coast and on Rügen. Obviously, open waters didn’t inhibit the concept’s spread, so it may well have arrived from Brittany via Britain.
Available AMS dates for TRB enclosures show the same pattern: The recently discovered Hamremoen enclosure in SE Norway has yielded a surprisingly early dating to the 39th cBC; in the 37th cBC follows Büdelsdorf, just next to the a/m Borgstedt Dolmen. Danish enclosures date to the late 36th cBC at earliest, and four of the eight early Danish enclosures cluster in N. Jutland.
Whatever the origin, from the 35th cBC onwards Megalithicism gained an enormous dynamic. By the late 34th century, it had reached East Frisia, and Drenthe in the NE Netherlands (the concentration of Helgoland flint in Drenthe hints at a possibly arrival by boat), as well as Scania and Central Mecklenburg. The spreading pattern through Lower Saxony has remained somewhat unclear, at least to me. In any case, the AMS dating supplied with the Sorsum sample indicates that the location was reached by the early 32nd cBC at latest.
The expansion is best documented for Central Germany, with the consecutive Tiefstich phases of Altmark Group (ca. 3500-3350 BC), Walternienburg (ca. 3350-3100 BC), and Bernburg (ca. 3100-2650 BC, possibly commencing somewhat earlier). While the initial spread concerned HG territory, Walternienburg marks the first expansion into a traditional EEF settlement area, around the Elbe-Saale confluence. The city of Bernburg is already deep in EEF territory, and by around 3100 BC, the Tiefstich sphere reached from Stettin in the NW to the south-eastern foothills of the Harz. This expansion is believed to have caused the transformation of the Baalberge Culture aka early TRB S into Salzmünde (late TRB S) [Ironically, the village of Baalberge has a few years ago been incorporated into neighbouring Bernburg]. The eponymous Salzmünde enclosure was around 3100 BC burnt down and destroyed by a GAC – Bernburg coalition, Afterwards, in the nearby Halle-Dölauer Heide enclosure, Bernburg people supplanted their stone cists over and across a Salzmünde graveyard, in obvious disregard of the latter.
Hence, the expansionist and intrusive character of Bernburg, and also of preceding Walternienburg, is archeologically well attested. However, little is known about their Tiefstich brethren west of the Harz. Were they also intrusive, or was it rather ideas and pots than people, which spread out southwestwards across the Lower Elbe ? If it was the former, to which extent did they absorb local HGs on their way (Neolithisation of northern Lower Saxony and the NE Netherlands is generally attributed to the TRB-Tiefstich expansion) ? Last but not least – is the full genetic story of TRB N/W already told by the Gökhem samples ? After all, these samples (slightly WHG-shifted EEF) stem from an area far outside the Erteboelle core, and as such prone to be colonised by incoming farmers without much local resistance. The fact that Gökhem has supplied the earliest Swedish megalithic burials, long before they appear in Scania, is further stressing the exceptionality of the location.
These are the questions I have in mind when speaking about an important geographical, chronological and cultural gap that needs to be filled aDNA-wise. It is ultimately about the Neolithisation of the Dutch-German plain (plus, by extension, Pomerania and the SE Baltics), and the phenomenon of megalithic burials, the most impressive monuments of the region prior to the erection of high medieval brick gothic cathedrals.
The Sorsum grave
The Sorsum grave lies on the southern TRB periphery (even outside of it if you trust Bakker’s map), at the eastern side of the “Hildesheimer Wald”, a low mountain range that separates the Leine and Innerste valleys, and marks the transition from the North German plain to the Middle German low mountains. As typical for this transition belt, the surrounding valleys and the onset of the North German Plain posess highly fertile loess soils, so the Sorsum area – unsurprisingly – housed an LBK settlement chamber.
The grave itself is not a standard megalithic burial – in fact, it isn’t megalithic at all. Instead, it consists of a 15 m long, some 2,1 – 2,4 m wide and 1,2 m deep chamber carved out of the solid rock, presumably covered by logs and overtowered with soil. The layout resembles the French “allées couvertes” and their German pendant, the “gallery graves” for which the Wartberg Culture further to the SW is famous (though there are also a handful of TRB gallery graves between the northern Harz foothills and the Saale). Moreover, just 2 km to the west, on the mountain top, lies the “Beusterburg”, with some 20 ha size the largest Michelsberg Culture causewayed enclosure in the Lower Saxony mountains. Close spatial assosiation of Michelsberg enclosures and subsequent Wartberg gallery graves is well attested, e.g. from Calden n. Kassel. This all gives reason to suspect a Wartberg Culture origin of the Sorsum grave. However, the 100 – 150 skeletons recovered from the Sorsum grave (often disarticulated, skulls piled up in pyramids etc.) were exclusively accompanied by Tiefstich and Bernburg pottery. Nevertheless, if there was a location where an EEF-rooted, middle-Germany MN population acculturated to “nordic” TRB-Tiefstich influence, it should have been Sorsum.
Finally, it is worth noting that the Sorsum grave / Beusterburg ensemble occupies a strategic location. The Leine valley offers the best southward transit through the low mountain ranges towards Franconia and ultimately the Adriatic Sea. It is wider and less curved than the Upper Weser valley with its many cliffs that in pre-modern times required frequent river crossings when travelling along the Weser by foot/ cart. Therefore, e.g. Roman campaigns towards N Germany preferred the Leine route, and it is also not by accident that the Hannover-Fulda (-> Frankfurt/ Munich) high-speed railway passes immediately east of the Sorsum grave.
Along the Innerste and its tributaries, the depression SW of the Harz and ultimately Thuringia and Bohemia can be reached conveniently. Northwestwards, this axis continues from Sorsum via the Weser crossing at the Müsleringen MK enclosure to the lower Ems and East/West Frisia.
Last but not least, the northern branch of the Hellweg (Duisburg – Soest -Hameln – Magdeburg) passes by Sorsum. The Hellweg forms part of what is arguably Europe’s most important West-East connection, namely Paris – Berlin – Kaliningrad – Vilnius -Moscow, the German part of which is designated as B 1 (federal road #1). Raetzel-Fabian (2002) argues quite convincingly for the Hellweg’s existence already during the MN, as route of the Michelsberg expansion into the northern Harz foreland. Subsequently, the Hellweg served for exchange between TRB-Tiefstich and the Wartberg culture that is, e.g., demonstrated by frequent finds of axes made from “Widaer Schiefer” in Wartberg Culture gallery graves (e.g. Calden, Züschen). “Widaer Schiefer” occurs exclusively in the Harz, processing sites are evidenced from Halberstadt-Spiegelsberge (“Sonntagsfeld”) and the Jätchenberg n. Quedlinburg (Bernburg enclosure). J. Müller (2000) uses the (non-)distribution of “Wiedaer Schiefer” axes as one of several indications of a clear-cut “border phenomenon” between the Tiefstich (Walternienburg-Bernburg) sphere and the Salzmünde culture to its southeast. Apparently, such a clear-cut cultural border didn’t exist between TRB-Tiefstich and Wartberg. Frequent occurence of Rijkholt and Spiennes flint in the Hellweg zone indicate the westward continuation of this axis already during the MN, while occasional amber finds point to some degree of interaction with the Kaliningrad area.
In summary, Sorsum, or better the adjacent Beusterburg, is likely to have been a major trade hub that could have attracted immigrants from all directions. This means that the single sample presented below should not be over-interpreted, he may well represent an outlier. More sampling will be required to make final conclusions about TRB-Tiefstich.
The TRB-Tiefstich sample
The Krause-Kyora paper hardly discusses the Sorsum TRB-Tiefstich sample. They only state that it was a male, from whom they extracted and mapped 9,856,001 human genomic reads (1.2 fold coverage). Data has been uploaded to the European Nucleotide Archive, accession No. PRJEB24921. Maybe someone can retrieve it for further analysis (uniparental markers, f-stats etc.).
However, their Supplementary Information includes a PCA in which the Sorsum sample together with previously published ancient populations is projected on 27 modern day West Eurasian populations (not shown). This PCA, with some amendments made by myself, is displayed below. In general, I don’t have much trust in PCA analysis, as it reduces genetic complexity to just two dimensions. Even more problematic is aDNA projection on modern populations, so the PCA dimensions are determined by modern rather than aDNA diversity. Last but not least, there is no information available how much of the genetic diversity is explained by PC1 and PC2. All in all, anything but an ideal source for analysis, but the only one available so far.
The first thing that can be noted is that the Sorsum sample plots quite a bit apart from the Swedish (Gökhem) TRB samples. This indicates that Gökhem, as I have reflected about above, probably only represents a part of the genetic diversity within the TRB-Tiefstich sphere [Baalberge (early TRB S), unfortunately not included in the PCA, was, IIRC, closer to EEF than TRB Gökhem, adding a further element of genetic differentiation inside the TRB horizon].
More specifically, TRB Sorsum appears to incorporate a substantial portion of HG ancestry, possibly in the 40-50% range when related to Anatolian farmers. In this sense, he is reminiscent of the Blätterhöhle MN samples (ca. 3600 BC, late Michelsberg). In fact, considering the Bätterhöhle’s location not too far from the Hellweg, migration from there to Sorsum is well imaginable. The find of a NW Italian Jadeite axe 2km north of the Bätterhöhle indicates connection to MN long-distance exchange networks.
However, one may equally think of a Blätterhöhle-like scenario, i.e. EEF from the low mountain ranges and the adjacent loess belt mixing with WHG from the North German plain, having occured along the whole northern loess border, including locally in Sorsum. Additional aDNA from comparable sites, e.g. the Belgian interaction zone between Michelsberg and Swifterband, or the Hellweg between Sorsum and Magdeburg, could provide further clarification whether Blätterhöhle is singular, or marks a general pattern of the 4th millennium BC.
Thirdly, the Sorsum sample in the PCA seems to display a slight pull towards SHG/ EHG, or maybe even the Steppe. Whether such influence is real and not just a projection artefact, and – if real – which admixture components were in play, of course requires further analysis of the whole genome. Considering that Bernburg posessed domesticated Botai horses, and there is some archeological indication of Bernburg – late Maykop contact, I wouldn’t in principle rule out some (individual) Steppe immigration into Central Europe already during the second half of the 4th millennium. More plausible, however, is a sizeable SHG element picked up in the SW Baltic Sea area, from where the Tiefstich expansion originated (and from where we unfortunately don’t have any aDNA, neither Erteboelle nor TRB, so far).
Whichever influence(s) differentiated TRB-Sorsum from TRB-Gökhem, and even more from TRB-Quedlinburg (Baalberge/ early TRB S; 110 km and ~400 years away) – he clearly represents a substantial intrusive element into this traditional EEF settlement chamber.
Another interesting observation is that Unetice in the PCA plots about half-way between Yamnaya and the Sorsum sample. CWC, in comparison, drifts towards SHG (or Narva ?). Of course, this observation requires confirmation by formal testing of the full genome. If it stands such test, this would indicate that the Sorsum sample isn’t an outlier, but quite representative of the population in the Dutch-German plain and adjacent areas, which admixed with incoming Yamnaya-like populations during the LN to ultimately form Unetice, and to a lesser extent also participated in the formation of CWC. This population may plausibly be labelled as TRB-Tiefstich, including Bernburg as late offspring, maybe plus a Blätterhöhle-like element in Wartberg.
Let me finally remark that according to the study’s figure supplements 8/9, TRB-Sorsum is projected in-between modern non-Basque Spanyards, and a cluster of modern Tuscans, Albanians and Bulgarians. Of course, this shouldn’t be over-interpreted (“Gothic motive“, etc.), but is probably owed to the fact that the Sorsum sample, as most South European populations, comprises very little Steppe ancestry. Nevertheless, it is noteworthy that – in contrast to EEF, Yamnaya, and also most CWC samples – TRB-Sorsum is projected inside the genetic variation of modern Europeans.
Let’s take that final remark a bit further: TRB is generally understood to have emerged from the interaction of the Michelsberg Culture with the Epi-Lengyel horizon (Gatersleben in Middle Elbe-Saale, Jordanow in Bohemia and Silesia, late Lengyel in Kujawy). Re-phrasing an intentionally simplifying remark by J. Müller: If you combine flat-based epi-Lengyel pottery with Michelsberg tulip beakers, you get Funnelbeakers. While the Michelsberg expansion was long believed to have stopped somewhere west of the former Iron Curtain, early MK presence (ca. 4000 BC) in Thuringia, Saxony and Bohemia, plus tulip-beaker inspired forms in Silesia, are now archeologically well attested; recent finds suggest that MK may also have reached the lower Oder. This yields a quite large zone of epi-Lengyel – MK interaction that stretches between Prague and Stettin, and possibly extends to W. Sweden.
Michelsberg is believed to have emerged from the Paris basin, w. backward linkage to Brittany, incorporating epi-Cardial and pastoralist HG (La Hoguette) elements. Lengyel had a Danubian origin and built on the Vinca metalurgical tradition. The Sorsum sample additionally suggests a sizeable WHG/SHG component in the TRB Tiefstichkeramik sphere that isn’t fully represented by the Gökhem samples, and most likely represents Swifterband-Erteboelle adstrate. In summary, TRB-Tiefstichkeramik may represent the fusion of both of the EEF streams (Mediterranean/Cardial, and Danubian/LBK, including their differing HG substrate), with North European post-Kongemose HG traditions. Even though it took to the LN to complete the mix with a fourth element, namely Steppe-like ancestry from Eastern Europe, the three a/m components should already have combined sufficient ancestry sources to yield a “modern European” – like result. And, there is hardly a better place imaginable for such a fusion to materialise than Hildesheim (-Sorsum), at the junction of the European main East – West (Moscow – Paris) and North – South (Norway – Sicily, modern E 45) communication axes.