A Dynastic Elite in Monumental Neolithic Society
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A dynastic elite in monumental Neolithic society Cassidy, L., Dublin, T., Kador, T., Lynch, A., Jones, C., Woodman, P. C., Murphy, E., Ramsey, G., Dowd, M., Dublin, T., Campbell, C., Jones, E. R., Dublin, T., & Bradley, D. G. (2020). A dynastic elite in monumental Neolithic society. Nature, 582, 384. https://doi.org/10.1038/s41586-020-2378-6 Published in: Nature Document Version: Peer reviewed version Queen's University Belfast - Research Portal: Link to publication record in Queen's University Belfast Research Portal Publisher rights Copyright 2020 Nature Research. This work is made available online in accordance with the publisher’s policies. Please refer to any applicable terms of use of the publisher. 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Cassidy1, Ros Ó Maoldúin1,2,3, Thomas Kador4, Ann Lynch5, Carleton Jones6, Peter C. 5 Woodman†,7, Eileen Murphy8, Greer Ramsey9, Marion Dowd10, Alice Noonan1, Ciarán Campbell1, 6 Eppie R. Jones1,11, Valeria Mattiangeli1 and Daniel G. Bradley1 7 8 Affiliations: 9 1 Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland 10 2 The Irish Fieldschool of Prehistoric Archaeology, National University of Ireland, Galway, Ireland 11 3 Archaeological Management Solutions, Consultancy, Kilrush, Clare, Ireland 12 4 UCL Arts and Sciences, University College London, London, WC1E 6BT, UK 13 5 Former Chief Archaeologist, National Monuments Service, Department of Culture, Heritage and the 14 Gaeltacht, Custom House, Dublin 15 6 School of Geography and Archaeology, National University of Ireland Galway, Galway, Ireland 16 7 Department of Archaeology, University College Cork, Cork, Ireland 17 8 Archaeology & Palaeoecology, School of Natural & Built Environment, Queen’s University Belfast, 18 Belfast BT7 1NN, Northern Ireland 19 9 National Museums NI, Cultra, Holywood BT18 0EU, Northern Ireland 20 10CERIS, School of Science, Institute of Technology Sligo, Sligo, Ireland 21 11 Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK 22 † Deceased 1 23 24 The nature and distribution of political power in Neolithic Europe remains poorly understood1. 25 During the period, many societies began to invest heavily in monument-building, suggesting an 26 increase in social organisation. The scale and sophistication of megalithic architecture along the 27 Atlantic seaboard is particularly impressive, culminating in the great passage tomb complexes2. 28 While megalith builders have often been proposed as co-operative networks of independent 29 communities, the human expenditure required for the largest monuments has led some to 30 emphasize hierarchy3, the most extreme case being a small elite marshalling the labour of 31 masses. Here we present evidence that such a social stratum was established during the Irish 32 Neolithic period. In a sampling of 44 whole genomes, we identify the adult son of a first-degree 33 incestuous union discovered within the most elaborate recess of the imposing Newgrange 34 passage tomb. Socially sanctioned matings of this nature are highly rare and occur almost 35 exclusively among politico-religious elites4, specifically within polygynous and patrilineal royal 36 families headed by god-kings5,6. We identify relatives of this individual within two other major 37 passage tomb complexes 150km to the west, as well as dietary differences and unprecedented 38 fine-scale haplotypic structure between passage tomb samples and the larger population, 39 implying hierarchy. This system emerged against a backdrop of rapid maritime colonisation 40 that displaced a unique Mesolithic isolate, although Irish hunter-gatherer introgression is 41 detected within the Neolithic population. 2 42 Ancient genomes have demonstrated common ancestry between the societies of the Atlantic 43 Neolithic7–9, while recent modelling has defined repeat expansions of megalithic architecture from 44 northwest France, at a pace implying more advanced maritime technology than previously assumed in 45 these regions10. This includes the spread of passage tombs along the Atlantic façade during the 4th 46 millennium BC, a period which also saw the arrival of agriculture to Ireland alongside other distinct 47 megalithic traditions. These structures reached one of their highest known concentrations and 48 diversities on the island. However the political systems underlying these societies remain obscure, as 49 does the genetic input from indigenous Mesolithic hunter-gatherers. 50 To investigate, we shotgun sequenced individuals from the Irish Mesolithic (n=2) and 51 Neolithic (n=42) to a median 1.14X coverage (Fig. 1a, Supplementary Tables 1, 2). We imputed 43 of 52 these alongside relevant ancient genomes (Supplementary Table 3), including an additional 20 British 53 and Irish individuals7,9,11. These were merged with a published imputed ancient dataset12 to allow for 54 finescale haplotypic inference of population structure13 and estimation of inbreeding. Four key 55 individuals were subsequently sequenced to higher (13-20X) coverage. 56 All major Irish Neolithic funerary traditions were sampled: court tombs, portal tombs, 57 passage tombs, Linkardstown-type burials and natural sites (Fig. 1a, c; Supplementary Information 58 section 1). Within this, the earliest Neolithic human remains from the island, interred at Poulnabrone 59 portal tomb14, are of majority Early_Farmer ancestry and show no evidence of inbreeding (Extended 60 Data Fig. 1; Fig. 1a), implying that from the very outset agriculture was accompanied by large-scale 61 maritime colonisations. ADMIXTURE and ChromoPainter analyses do not distinguish between the 62 Irish and British Neolithic populations and confirm7,8 the Spanish Early Neolithic as the best proxy 63 source of their Early_Farmer ancestry (Fig. 1d, Extended Data Figs. 1, 2), emphasising the 64 importance of Atlantic and Mediterranean waterways in their forebearers' expansions. 65 Overall, no increase in inbreeding is seen through time in Neolithic Ireland, indicating that 66 communities maintained sufficient size and communication to avoid matings of 5th degree relatives or 67 closer (Fig. 1a). However, we report a single extreme outlier interred within Newgrange passage 68 tomb, a focal point of the UNESCO monumental landscape of Brú na Bóinne (Fig. 2a). Incorporating 69 over 200,000 tonnes of earth and stone, this megalithic mound is one of the most spectacular of its 3 70 kind in Europe15. While externally designed for public consumption, internally, the tomb consists of a 71 single narrow passage with a specialised ritual inventory, whose winter solstice solar alignment would 72 have been viewed only by a select few. Unburnt, disarticulated human bone was found concentrated 73 within the most elaborately decorated recess of the terminal cruciform chamber, including the cranial 74 remains of an adult male (NG10; Fig. 2b; Supplementary Information 1.4.1). This exceptional 75 location is matched by an unprecedented genomic heritage. He possessed multiple long runs of 76 homozygosity (ROH), each comprising large fractions of individual chromosomes (Fig. 2e; Extended 77 Data Fig. 3a), and totalling to a quarter of the genome (Inbreeding Coefficient = 0.25). This marks 78 him as the offspring of a first order incestuous union, a near universal taboo for entwined biological 79 and cultural reasons4. However, given the auspicious nature of the interment, his parentage was very 80 likely socially sanctioned. 81 While simulations cannot distinguish whether his parents were full siblings or parent and 82 offspring (Extended Data Fig. 3), the only definitive acceptances of such matings occur among 83 siblings, specifically within polygynous elites, as part of a rarely observed phenomenon known as 84 “royal” or “dynastic” incest4,6,16. In all documented cases (e.g. Hawaii, Inca Empire, Ancient Egypt), 85 this behaviour co-occurs with the deification of political leaders and is typically limited to ruling 86 families, whose perceived divinity exempts them from social convention. Both full and half-sibling 87 marriages are found most commonly in complex chiefdoms and early states, being generally viewed 88 as a means to intensify hierarchy and legitimise power in the absence of more advanced bureaucratic 89 systems, alongside tactics such as extravagant monumentalism and public ritual17,18,19. We propose a 90 comparable set of social dynamics was in operation in Ireland by the Middle Neolithic, and, given the 91 construction of solstice-aligned passage tombs similar to Newgrange in Wales, Orkney and Brittany20, 92 may have occurred outside the island as well. Notably, levels of consanguinity are consistently low 93 and decrease through time across our wider ancient dataset (Extended Data Fig. 4), with only