Ancient DNA and the European Neolithic: Relations and Descent

Chapter 1

Introduction: questions of descent, relationships and identity

Alasdair Whittle and Joshua Pollard

THE AIM OF THIS VOLUME

This volume, coming out of the annual Neolithic Studies Group day conference (held online in November 2021), explores the impact of recent archaeogenetic work focused on the Neolithic and Copper Age in Europe. Its temporal and geographic scope runs broadly from the 7th to the 3rd millennia cal BC, with a particular but by no means exclusive interest in Britain and Ireland, and with one paper that examines evidence from the Near East, going back to the 10th millennium cal BC (and even earlier). Our aim is to bring a range of colleagues from the disciplines of archaeogenetics and archaeology under the same cover, and to foster extended dialogue, critique and discussion in a way that is routinely not possible in the normal medium of short papers in scientific journals.

THE aDNA REVOLUTION

There has been a fundamentally important aDNA revolution in recent years. This development offers a series of key insights not available by other means into central questions within archaeology relating to population histories, descent and relationships, and by implication also identity, at many scales and of many different kinds. These are all complex matters, which raise a host of challenges for both geneticists and archaeologists.

The idea of revolution can often be exaggerated, but the term certainly seems to fit in the case of archaeogenetics, especially over the last decade (Rutherford 2016; Reich 2018; Jones and Bösl 2021). As a viable science its beginnings were precarious (see Richards, this volume), but enhanced method and widespread application now offer remarkable insight into key population dynamics in human history. One recent characterisation by an archaeologist refers to ‘Next Generation Sequencing (NGS), the recovery of dense concentrations of endogenous DNA from the petrous bone of the human skull, and the sequencing of entire human genomes (the complete set of genetic information for a given organism)’ (Thomas 2022, 1); it is increasingly worthwhile to keep an eye out for the distinction between genome-wide and genuinely whole genome analyses. These innovations and improvements have come to expand radically the amounts of information available, compared to the situation just a decade and more ago when the main emphasis was on mitochondrial and Y-chromosome data (e.g. Sykes 1999; Bramanti et al. 2009; Brandt et al. 2013; 2015; but see also Richards, this volume, for the continuing value of those datasets). Adam Rutherford (2016, 4) has referred to ‘an epic poem in your cells…an incomparable, sprawling, unique, meandering saga’. The ability now of archaeogeneticists to trace the descent of populations and detailed relationships among groups and individuals is astonishing, especially if one is old enough to remember the research days of, say, the 1970s and 1980s (e.g. Whittle 1977), when big questions like the nature of the Mesolithic–Neolithic transition in Britain had to be addressed with archaeological evidence and assumptions alone, and when the closest DNA came to making a contribution was the suggestion of the relevance of modern blood-group patterning across Europe to earlier population histories (Ammerman and Cavalli-Sforza 1984; Reich 2018, xv–xvii).

Since about 2015, there has been a veritable flood of publications rolling out this aDNA revolution (Reich 2018, xviii), with a global reach and stretching far back in time into the Palaeolithic (Rutherford 2016, 26–7). It is hard to think now of an archaeological question not affected by the aDNA revolution.

One of the greatest impacts of recent archaeogenetic work has been felt in the study of the European Neolithic and Copper Age. That area and that timespan have been centrally involved in the great flow of recent papers. There are several important headlines. Three major ones involve arrivals of new population, at the start and end of the European Neolithic/Copper Age, underlining older archaeological opinion about colonisation and population movement (e.g. Ammerman and Cavalli-Sforza 1984; Gimbutas 1989; Sheridan 2010; Rowley-Conwy 2011). First, at the start of the Neolithic, paper after paper seems to demonstrate the reality of the arrival of new people of Aegean and ultimately Near Eastern genetic ancestry, in dominant numbers, now across nearly every region of Europe, though not always in exactly the same proportions and of course appearing across a shifting timescale from the 7th to the early part of the 4th millennium cal BC (e.g., selectively, Skoglund et al. 2014; Mathieson et al. 2015; 2018; Szécsényi-Nagy et al. 2015; 2017; Cassidy et al. 2016; 2020; Hofmanová et al. 2016; González-Fortes et al. 2017; Lipson et al. 2017; Olalde et al. 2018; Brace et al. 2019; Rivollat et al. 2020; Allentoft et al. 2022; Ariano et al. 2022; Marchi et al. 2022).

The next startling headline, without doubt also the most controversial, figures the appearance in central and parts of western Europe of people of steppe-related genetic ancestry, manifested archaeologically in the Corded Ware-Single Grave phenomenon of the early 3rd millennium cal BC, and very probably linked to the slightly earlier Globular Amphorae culture and beyond that to the Yamnaya culture and related groups far to the east (Anthony 2007; Allentoft et al. 2015; 2022; Haak et al. 2015; Scorrano et al. 2021). This shift in genetic signatures has been seen as the consequence of a ‘massive’ or ‘mass’ migration (Haak et al. 2015, 207; Reich 2018, 110), spurred on in one account especially by horse-riding male warrior bands, the forerunners of a new and much more mobile, pastoral population (Kristiansen et al. 2017).

The third arrival has been seen as on a more restricted scale. Bell Beaker people across central Europe from broadly the middle of the 3rd millennium cal BC onwards also had steppe-related ancestry, but counter to the suggestions of the long-established archaeological literature, there is no clear support for significant Beaker-using population movements within continental western and central Europe as a whole, because sampled Beaker people in Iberia showed significant continuity with preceding populations and Beaker people in central Europe had significant steppe-related ancestry (Olalde et al. 2018; Reich 2018, 115). However, seemingly resolving another long-standing debate, it seems clear that Beaker-using people did come into Britain and Ireland in significant numbers, in Britain from around 2400 cal BC and perhaps predominantly from the area of the Lower Rhine and the Low Countries (Olalde et al. 2018; Parker Pearson et al. 2019; see also Armit and Reich 2021; Brace and Booth, this volume), echoing the models of much earlier studies based on material culture and funerary rite (Clarke 1970).

There have been other stories of great significance. Following early Neolithic arrivals in central Europe, there is genetic evidence for the surprisingly long survival in certain contexts of people of Mesolithic or hunter-gatherer descent (Bollongino et al. 2013) and in the Carpathian basin for the gradually increasing representation of characteristically hunter-gatherer haplotypes (Szécsényi-Nagy et al. 2015; 2017). We are also probably witnessing a shift to more detailed studies of particular contexts, whose results offer important insights into the relatedness of smaller social groups (Sánchez-Quinto et al. 2019). There have been stunning recent results at this more intimate scale, from the brothers at Trumpington Meadows, Cambridgeshire (Scheib et al. 2019; cf. Fowler 2022), or the very close, incestuous interbreeding at Newgrange, Co. Meath (Cassidy et al. 2020; see also Cassidy, this volume), to the five-generation patriline within the long cairn at Hazleton, Gloucestershire (Fowler et al. 2022). Add to these investigations a welter of other information – from details of personal appearance including skin, eye and hair colour (Rutherford 2016, 64) and even stature, to aspects of diet, including lactose tolerance (Anguita-Ruiz et al. 2020; Evershed et al. 2022), disease, including evidence now for plague as far back as the 3rd millennium cal BC (Rasmussen et al. 2015), and the histories of a spectrum of species of domesticated crops and animals (e.g., selectively, Brown et al. 2015; Scheu 2018; Librado et al. 2021) – and it is plain, despite the risk of hype (Jones and Bösl 2021) on the one hand and of undue pessimism (Furholt 2019a) on the other, that the idea of a revolution in understanding having taken place is well justified.

QUESTIONS TO BE ASKING

All these developments raise a series of important questions, which it is the aim of this volume to debate. When as archaeologists without scientific training or technical expertise in either genetic procedures or increasingly sophisticated statistical analyses we read paper after archaeogenetic paper, we come across recurrent questions and matters that involve interpretation. We want to be assured that the most precise chronologies possible are being applied (Whittle 2018); at times in the short space routinely available in leading scientific journals rather compressed or fuzzy chronologies are often deployed. For example, the development of both the LBK in central and western Europe, and the appearance and spread of the Neolithic in Britain and Ireland, may have played out over several centuries, but some of the accounts of the genetics involved seem to rely on a kind of frozen, generalised snapshot. We would like to know more about scales, from varying kinds of population movement to the effects of indigenous involvement (e.g. Mithen 2022), from respectively hunter-gatherers at the start of the Neolithic to the already established communities living across central and western Europe by the early 3rd millennium cal BC. There can be all manner of conditions of and reasons for colonisation, migration and movement (Anthony 1990); these can be part of varying social strategies as much as a response to external push or pull factors (e.g. Hofmann 2015; 2016; 2020), and so scale can vary enormously. Likewise, we are interested in the effect of local, existing knowledge. If, as is repeatedly suggested in the literature, the contribution of hunter-gatherers to initial early Neolithic genetic signatures was real but small (e.g. Brandt et al. 2014; Nikitin et al. 2019), how did that translate in terms of the transmission of knowledge, for example of the lie of the land and of lithic resources (Mateiciucová 2008)? The question is pertinent, too, when considering later migration events, such as that of Beaker groups into Britain and Ireland, where early co-presence in areas around major Late Neolithic monument complexes suggests landscape knowledge transmitted through close contact with local communities. We are interested, for the same sorts of reasons, in whether processes of population arrival and replacement, and of small-group composition, were uniform or diverse; we want to resist the universal application of single models. Two brief examples would be the uneven and varying archaeological evidence for the Corded Ware presence in central and western Europe, with novel pottery alone perhaps the sole indicator of change in the Alpine foreland (Ebersbach et al. 2017), and the nature of family and lineage groups in cemeteries and collective burial deposits. We will have to see whether these all represent closed and tightly defined social groupings (e.g. Haak et al. 2008), or whether more open access and more fluid arrangements can also be found in future investigations (cf. Fowler et al. 2022, 1); we will briefly discuss the case of Hazleton further below.

Related to questions of uniformity and diversity, we are interested in sampling density. We acknowledge that whole genome analysis and statistical tools (Speidel, this volume) now open up for analysis a multiplicity of relationships and genetic histories even from small numbers of analysed individuals (Booth 2019, 3), but acceptance of that important point does not remove the general desirability of increasing the density of sampling across Europe, not least if possible for Mesolithic populations. Like many others, we are concerned that interpretation of aDNA results should not be confined within restrictive and rigid definitions of culture and identity (a worry voiced by many commentators, including Frieman and Hofmann 2019; Crellin and Harris 2020). The obvious main target here has been the notion of a bounded, self-defining and uniform Corded Ware culture, which may be quite inadequate to catch the varying range of innovations across central and western Europe in the late 4th and early part of the 3rd millennium cal BC (Furholt 2014; 2017; 2019a; 2019b; see also Kristiansen, this volume). Finally, we are interested in how aDNA results can help us to do better archaeology. Take the Beaker phenomenon, for which neither conventional culture-historical accounts of repeated movements and migrations nor the processual emphasis on a package of cultural ideas and practices have turned out adequately to capture the complexities of the situation across continental Europe and Britain. What are the subtler clues that archaeologists could revisit, in the light of aDNA results?

There is space here, by way of introduction to the kinds of interpretive challenges that recurrently face us, only to take three of these examples a little further. Above, we have raised questions mainly for the archaeogeneticists, but there are questions too for archaeologists.

First, we reflect briefly on the debate about the end of the Neolithic (in the broad sense, without going into details here of regional Copper Age schemes). We have outlined above the principal genetic findings of recent years, and noted interpretations of massive or mass migration, with the further refinement in one model of male warrior bands with horses and wheeled vehicles leading this major incursion from the east. The most persistent and fierce critic of this view has been Martin Furholt (2014; 2017; 2019a; 2019b). He has underlined the case for Corded Ware and indeed Yamnaya variability (Furholt 2014; 2019b, 119, 121; cf. Heyd 2017; 2021; Preda-Bălănică et al. 2020; and see Preda-Bălănică and Diekmann, this volume), supporting the empirical cases with a repeated emphasis on the generally if not universally polythetic nature of culture. In explicit response to Kristiansen et al. (2017), he proposes instead the spread of a network of related but regionally and chronologically varying mortuary practices, which he dubs the Single Grave Burial Ritual Complex (SGBR: Furholt 2019b). So far, however, despite fierce criticism of what he sees as conventional and out-dated aDNA-based narratives (Furholt 2019a), he has not sought to explain how such a network of practice might be conceptualised in detailed social terms, other than by reference to rather general notions of social integration on the one hand and of local histories on the other (Furholt 2019b, 123, 125) nor how its operation might have affected the very considerable increase in steppe-related ancestry revealed by the geneticists (even accepting the valid point that indigenous population might well be under-represented in such a mortuary shift; cf. Booth et al. 2021). We reflect that it is hardly necessary to accept either of the two visions of culture proposed, since culture can be seen as performance and varies accordingly (Carrithers 1992), and that archaeologists have become unaccustomed to specific and particularising historical narratives, often seeming to prefer generalised models, routinely imported from other disciplines (Whittle 2018). There is plenty at stake here beyond the specifics of Yamnaya and Corded Ware aDNA.

In contrast, there seems to be much greater consensus about the general impact of aDNA studies on our view of the processes of change at the start of the Neolithic across Europe; colonisation by new people seems the undisputed major driving force. Lest we become in turn complacent about this horizon, we see all this as shifting and resetting the terms of debate rather than ending it. There are still many questions to be addressed anew, in terms of timing, variability, directionality and sources (see Bánffy, this volume). There are, as raised above, important matters of how to quantify the contribution of indigenous people to early Neolithic genetic signatures and how to evaluate this in wider social and cultural perspectives. It is worth noting that a recent paper has attempted to make the case for a larger Mesolithic input in the case of Britain (Thomas 2022), even though it seems to us to require too much special pleading (cf. Thomas 2013). And if the latest picture from aDNA for Denmark is of an almost complete replacement of hunter-gatherers (Allentoft et al. 2022), what happens to older archaeological arguments for continuity there in terms of lithic traditions and knowledge of the landscape?

Finally, the need for continuing interrogation and interpretation seems to us equally vital as attention shifts to the close encounters of mortuary and other deposits. The analysis of the Hazleton collective deposit offers an interesting case in point (Fowler et al. 2022). A prominent feature of the remarkable array of relationships within the two chambers of the monument was the finding that one man had reproduced with four women, though the investigations could not demonstrate whether that represented ‘serial monogamy or polygyny’ (Fowler et al. 2022, 3). The study goes on to suggest the enduring importance of maternal sub-lineages and the inclusion of biologically unrelated people, within a dominant patriline. One commentator, in contrast, has expressed ‘deep suspicion that an alpha male was able to impregnate several women and that he was considered to be more important to the community than the women’, referring further to ‘the hippy trap’ of assuming that the community had any say in the selection (Catling 2022, 62). This is perhaps unhelpful, and not for the first time (cf. Frieman and Hofmann 2019) modern assumptions collide with complex evidence from the past. One way to take things further may be more Bayesian chronological modelling, using genetic relationships as informative priors, and a recurrent awareness of, and willingness to explore, the potentially varied constitution of kinship and other forms of social relatedness in settings remote from our own (cf. Brück 2021; see also Kristiansen, this volume)

HISTORIES OF DESCENT, RELATIONSHIPS AND IDENTITY: THIS VOLUME

There is therefore no shortage of things to think about in relation to descent and relationships, and to the implications of the new and still accumulating aDNA results for how we should consider individual and group identities.

In the papers presented here, Martin Richards offers a timely, critical overview of the development of aDNA studies and emphasises the continuing contribution of the analysis of uniparental markers. Kristian Kristiansen defines a series of challenges in aDNA research, ranging from matters of sampling, research ethics, terminology, open access to data, and a shift from interdisciplinarity to transdisciplinarity (‘a unity of intellectual frameworks’). He outlines, too, interpretive challenges that include the investigation of how genetic admixture processes relate to cultural admixture processes, and the translation of biological mating processes into rules of kinship and marriage. Bruno Ariano and Daniel Bradley address the question of whether Neolithic seascapes were accelerants or retardants of genomic exchange. Given that agriculture was spread via migration rather than acculturation, for the examination of subsequent networks among genomically similar Neolithic populations a more in-depth interrogation of genomic diversity is needed. This is provided by a next generation of analyses that consider similarity within and between genomes based on shared chunks of chromosomes. The detailed data required for these methods can be obtained by genome-wide imputation in a cost-effective leveraging of partially sequenced genomes. These genealogical approaches parse fine structure among European Neolithic genomes and unveil the retarding effects of seascapes for genetic relations, rather than their connectivities. Such analyses highlight how limited reproductive networks were on some island communities, such as those on Malta, Orkney and Gotland, an observation that might be balanced against material evidence for varying maritime connection. Leo Speidel considers new statistical tools that we can use to infer the joint history of hunter-gatherers and farmers in Europe, extrapolating their genealogical relationships to times where data are comparatively sparse.

The bulk of the other papers give case studies relating in the first place to particular times and places, but engaging consistently with the sorts of broader issues already discussed. Eva Fernández-Domínguez uses genome-wide ancient human DNA data to show that a strong genetic substructure existed among the first farming populations of the Fertile Crescent (c. 8000 cal BC). This suggests multiple origins of farming and a local evolution of farmer groups from preceding hunter-gatherer populations with limited gene flow at the onset of the Neolithic. To date, the available Neolithic palaeogenomic data indicate a mainly Anatolian origin for the continental route of the Neolithic expansion, punctuated by local episodes of admixture with local hunter-gatherer groups. According to other lines of evidence, however, an earlier parallel, sea-mediated expansion from the Levantine and Anatolian coasts cannot be discarded. She strongly advocates the integration of multi-disciplinary approaches, including aDNA, in the search for a more nuanced understanding of the population changes associated with the emergence of farming in the Near East. Maxime Brami and Yoan Diekmann consider whether foragers became farmers in south-east Europe, hinging on the interpretation of the famous site of Lepenski Vir; armed with aDNA results, they challenge many previously accepted readings of the evidence, arguing for a much more active and dominant role for incoming farmers of Aegean ancestry. Eszter Bánffy ranges across south-east and central Europe, with special reference to the Carpathian basin, in a further effort to reconcile aDNA data with the archaeological record, as well as some contradictions, and to underline the diversity of the Neolithic transition. By bringing together information about the genetic ancestry of individuals and the mortuary archaeology of burial practices, Bianca Preda-Bălănică and Yoan Diekmann investigate the relationship between descent and identity in the kurgans and flat cemeteries of the region, from the 5th to the 3rd millennium cal BC. While many individuals with no steppe-related ancestry are buried according to Balkan-Carpathian basin burial practices, they find that a significant number of them were also buried according to Pontic-Caspian steppe practices. Their results suggest that operating with the prevalent dichotomy only obscures the complexity of processes taking place in the region, indicating that ancestry is at most one factor amongst others contributing to social identity.

Three papers then consider aspects of the Neolithic in Britain and Ireland. Selina Brace and Tom Booth combine to provide an updated and authoritative review of ancestry change in Neolithic Britain, incorporating new results, adding greater detail than presented by Brace et al. (2019) and giving some contrast with the later ancestry shift that occurs in Britain from c. 2500 cal BC. They note that initial EEF (Early European Farmer) migrations into Britain probably took place over several hundred years, followed by little further intermarriage with groups from continental Europe. A complex picture is presented of matters of origins, admixture with local Mesolithic groups and genetic relatedness in varied 4th millennium cal BC contexts. There is evidence of substantial population continuity into the first half of the 3rd millennium cal BC, but of surprisingly low population sizes during this period; while the persistence of Neolithic-descended populations through the second half of the 3rd millennium cal BC alongside new continental migrants carrying steppe-related ancestries is emphasised.

In her genomic survey of the Mesolithic–Neolithic transition in Ireland, Lara Cassidy reviews analyses so far of both Mesolithic and Neolithic people. She suggests that relative population sizes were key factors in the process; the Mesolithic population was probably both small and isolated by the 5th millennium cal BC, and probably vastly out-numbered by Neolithic newcomers, who may well have arrived from points of origin shared with migrants into Britain. Alison Sheridan and Alasdair Whittle then reflect on how aDNA results have impacted on their differing models of the processes involved in the Neolithisation of Britain and Ireland, and seek to identify remaining and future challenges for both geneticists and archaeologists.

To round things off and to look to the future, Susan Greaney argues for a ‘slow science’ approach to collaborative aDNA research that makes room for nuanced and reflexive interpretation drawing on the humanities, particularly anthropological and archaeological theory. Genetic change and relatedness need to be considered in the light of the partial nature of the archaeological record and the samples available to researchers, couched using careful terminologies, interpreted alongside other strands of archaeological evidence and grounded in critical approaches to social identity and kinship beyond the biological and indeed, beyond the human.

As in the wake of most revolutions, there is still much to do.

ACKNOWLEDGEMENTS

We are very grateful to both Tim Darvill and Kenny Brophy of the Neolithic Studies Group and our co-editor Susan Greaney for their help and advice throughout the processes of organising and running the online meeting, and then achieving this volume; Alison Sheridan also gave invaluable editorial help. We thank Eske Willerslev, Volker Heyd, Chris Fowler and Neil Carlin, who gave excellent talks on the day but were unable to contribute here because of other commitments; Volker gave us up-to-date references for recent Yamnaya research. Martin Richards, Maxime Brami, Bianca Preda-Bălănică and Yoan Diekmann have bravely stepped in to provide papers and maintain the breadth of our coverage. Finally, we thank Julie Gardiner and Jessica Hawxwell of Oxbow Books for their patient guidance.

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