The complexities of 3rd millennium Steppe-related migrations

Open access paper Mobility and Social Change: Understanding the European Neolithic Period after the Archaeogenetic Revolution, by Martin Furholt, J. Archaeol. Res. (2021).

Content under CC-BY license. Interesting excerpts (emphasis mine, stylistic changes for clarity):

This detailed picture of Caucasian population history shows that the initial assertion in the 2015 papers, namely of a one-way migration from east to west, was a simplification supported by a variant of admixture analyses that featured Yamnaya as one unified genetic element (e.g., Haak et al. 2015, fig. 3), which led to calculations of Corded Ware individuals showing 75% Yamnaya ancestry. This then resulted in historical scenarios of near-total extinction of the native population in central Europe (Haak et al. 2015, p. 210). There is nothing wrong, per se, with the idea to look for the least complex population model, or to try to find the admixture model with the fewest necessary source populations, but when this model is then taken to represent social processes, it is unjustified to assume that the simplest explanation best represents reality. This leads to the resurgence of block-like entities, the narrative of a single-event, unidirectional, massive migration from the steppes into central Europe.

A Critique of the Kristiansen Narrative

However, the narrative developed by Kristiansen et al. also has several problematic aspects. It stands on a number of weak premises, reifying the traditional concept of archaeological cultures: “migrant Yamnaya people” and “expanding Corded Ware groups” are featured as main actors consisting of socially circumscribed groups of people, collectively migrating and fighting with “indigenous Neolithic groups” who are portrayed as largely immobile and passive. Agency is only granted to men; whenever women are found to be mobile, the interpretation is that they were abducted or handed around by men. A reversed case, like the Yamnaya Kurgan Sárrétudvari-Orhalom in eastern Hungary (Gerling et al. 2012), in which a burial sequence started with a local woman, followed later by interments of, among others, nonlocal men, is to my knowledge never even discussed as representing matrilocality and male exogamy (see Furholt 2019a). (…)

chronology-regional-archaeological-europe-neolithic
Sketch of the chronological and regional position of the most important archaeological units mentioned in the text. The two different colors indicate the relevance of these units for the first main part of the text (Neolithic expansion) and the second part (third millennium mobility)

Several of the concrete empirical arguments that back the Kristiansen model also warrant a further discussion.

  • The finding of yersinia pestis on Neolithic individuals is not proof of an epidemic, as nothing is known about the virulence or deadliness of the bacterium during that period. On the contrary, the fact that such bacteria have been found only in a small number of Neolithic individuals, spread out over 1500 years over the whole of Eurasia, points to low rates of transmission and mortality, at least to a scenario very different and less dramatic than the late medieval plague of the 14th century (Fuchs et al. 2019).
  • (…) the male bias in the influx of steppe ancestry (Goldberg et al. 2017) is contentious (Lazaridis and Reich 2017), and an uptick in violence during the third millennium BC cannot be inferred from two mass graves. Such finds have been made throughout prehistory (e.g., Carman and Harding 1999; Ralph 2013; Thorpe 2003), and to make inferences about trends and changing levels of violence from skeletal materials, one has to systematically collect and quantify signs of violence on human bones in the archaeological record. For modern Germany, such an endeavor has been undertaken by Peter-Röcher (2007), who collected and discussed skeletal materials with signs of injuries through the prehistoric periods. She did detect for Corded Ware burials a rate of injuries that is slightly higher than in earlier periods but clearly lower than in the Late Bronze Age or the Iron Age.
  • Finally, the trend of a reduction Y-haplogroups (Zeng et al. 2018) is a worldwide phenomenon, which started around 10,000 BC, and thus cannot be taken to explain anything that would be historically specific for the third millennium BC in Europe. Nevertheless, the dominance of R1a and R1b Y-haplogroups in Europe after the third millennium BC, as opposed to a more diverse Y-haplogroup composition in the preceding period is a point worth investigating. Still, the simple picture of Yamnaya-related male lineages migrating into Europe and killing off all the native males is not consistent with the data.
yamnaya-corded-ware-bell-beakers
Map of Europe showing the spatial distributions of the three most prominent archaeological units during the 3rd millennium BC, Yamnaya, Corded Ware, and Bell Beakers. The newly emerging single burial complex intersects Corded Ware and Bell Beakers

While almost all male individuals from Yamnaya burials share the haplogroups R1b-Z2103 and Q1a2 (Wang et al. 2019), the great majority of all Corded Ware males share a different haplogroup, R1a (Mathieson et al. 2018). R1b, but of a different variant (P312), is the most frequent Y-chromosome haplogroup among male burials from Bell Beaker contexts (Olalde et al. 2018). Thus the core of the Kristiansen et al. narrative—Yamnaya males migrating into central Europe and constituting the new Corded Ware complex—is contradicted by the data. The majority of males buried in Corded Ware graves are not descendants of the Yamnaya males of which we know. The question then is from where did the R1a lineages that are the majority in Corded Ware burials come. We find R1a in Majkop graves, as well as in individuals connected to the so-called eastern European Forest Neolithic and the “Ukrainian Eneolithic” populations (Haak, personal communication 2019). This indicates that Yamnaya is not the only source of “steppe ancestry” in individuals associated with central European Corded Ware. An alternative scenario assumes that Yamnaya burials were reserved for a few selected families in the steppe, while those who migrated belonged to other, disenfranchised lineages from the same region. While such a scenario is thinkable, it is also far from an Occam’s razor-like model usually preferred in the migration debates.

pca-mathieson-2018-yamnaya-corded-ware
Simplified representation of a principal component analysis (adapted and altered after Mathieson et al. 2018, extended data figure 1) displaying the main patterns whole genome samples from late Epipalaeolithic/Mesolithic and Neolithic individuals, projected upon 777 modern samples (gray areas). Clusters commonly used are indicated by colored shading: EAF: early Anatolian farmers; WHG: western hunter-gatherers; EHG: eastern hunter-gatherers; SHG: Scandinavian hunter-gatherers; ANE: ancient north Eurasians/Native Americans; ICHG: Iranian Neolithic and Caucasus hunter-gatherers; LN/EBA: Late Neolithic and Early Bronze Age in central Europe, southern Scandinavia and the Carpathian Basin; steppe ancestry was defined with reference to Yamnaya-related samples. Some individual samples connected to archaeological units discussed in the text are shown for illustrative purposes, without being a representative selection

In addition, the fixation on Yamnaya as the source for Corded Ware formation is not a result, but rather a premise to the earlier aDNA studies that discussed third millennium migrations (Furholt 2018b, p. 168). Other eastern European source populations are possible, and the new genetic element could be connected to the Forest Neolithic or Pitted Ware complexes, all of which connected eastern and central Europe prior to and in the third millennium BC. Indeed, Corded Ware subgroups such as Fatyanovo in western Russia represent in themselves an archaeological link between central and eastern Europe (Ershova and Krenke 2013), a link for which there is as yet very little knowledge about connected biological patterns. More data for the Belorussian and western Russian Corded Ware groups should shed more light on this issue, but already now it is highly unlikely that the influx of steppe ancestry will be explained by one single process or is the result of one group of people migrating. Rather there seem to be more and different processes, and more and different groups of people involved. Whereas the new single grave burial ritual associated with Corded Ware (Furholt 2019a) started around 2900 BC, there is no temporal priority for Yamnaya kurgan graves in the Carpathian Basin over early Corded Ware (as it was long supposed). Thus, it now seems that there might be a first, pre-Yamnaya movement of people from the east into central Europe who were buried in the earliest single graves with Corded Ware. During the same time, Yamnaya graves are found in the Carpathian Basin, and at a later stage some individuals from that source mixed with the first Corded Ware generations. This second, more closely Yamanya-associated influx of people became more dominant in central European single graves only after 2500 BC, when it was predominantly connected to Bell Beaker materials.

single-grave-burial-complex
The main elements of the new, 3rd millennium single burial complex in Europe (after Furholt 2019a): individual aggrandizement (the single burial in a crouched position, under a burial mound), male warriorhood (specialized weapons in male graves), gender differentiation, (reflected by body orientation rules). Drinking vessels of different forms also are prominent: Corded Beakers, Bell Beakers, or Bronze Age cups

Comments

As any of you with experience reading Furholt’s writings will understand, his predominantly anti-migrationist narrative permeates yet again all accounts of potential Neolithic and Bronze Age population movements. There is thus a constant look for models much more complex than warranted by genetic data, with the general aim of avoiding simplistic ideas.

That leads occasionally to an apparent defiance of some of the most straightforward inferences that can be made from the samples we currently have.

Nevertheless, an interesting interpretation can be found in his recently developed framework (e.g. 2018, 2019) of the “single grave burial complex” (SGBC), with commonalities shared and transferred during the European Bronze Age (such as among CWC, BBC, or Únětice), revealing intense contacts despite the obvious cultural and genetic differences between groups.

Still, the most relevant piece of information from the paper comes from what can be read between the lines about upcoming population genomic papers, even though most of it is already expected (or, in some cases, already leaked) if you follow this blog.

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