Periodic Reporting for period 4 - COMMIOS (Communities and Connectivities: Iron Age Britons and their Continental Neighbours)
Reporting period: 2024-04-01 to 2025-09-30
Recent breakthroughs in ancient DNA and isotope analysis are transforming our understanding of diversity, mobility and social dynamics in the human past. COMMIOS integrates these cutting-edge methods on a scale not previously attempted, to provide a radically new vision of Iron Age communities in Britain (800 BC – AD 100) within their wider European context. At the broad scale, we conducted the first concerted programme of genome-wide ancient DNA analysis on Iron Age populations anywhere in the world, extending our work into the Middle-Late Bronze Age as the project developed. Along with isotope analysis, underpinned by both osteoarchaeological and cultural archaeological approaches, this has enabled us to address issues of population movement and inter-regional connectivity. We have also used these new scientific methods to examine the structure and social dynamics of Iron Age societies.
COMMIOS represents a collaboration between archaeologists, geneticists and the wider heritage sector represented by museums and commercial archaeological organisations. As such, it has formed a powerful vector for the dissemination of knowledge and understanding of cutting-edge scientific approaches to the human past. Our work on long-term population history has generated new insights into the complex inter-relationships between past communities in Europe, prompting fresh perspectives on national identities and new understandings of the fluidity, diversity and mobility of European populations.
Our overall objectives were:
1: To establish the patterning of genetic diversity across Iron Age Britain and to examine the extent to which this corresponds with (a) traditional cultural boundaries, identified through settlement patterns, material culture and linguistic evidence, and (b) genetic clusters identified from analyses of modern DNA.
2: To examine the degree of mobility and connectivity within Iron Age communities in Britain through a suite of isotopic analyses.
3: To characterise the composition of Iron Age cemetery populations in Britain (as a proxy for living communities) in relation to age, sex, diet, health, disability and social inequality.
4: To identify familial relationships within Iron Age funerary contexts in Britain and the degree to which Iron Age communities practiced matrilocal or patrilocal marriage patterns.
COMMIOS represents a collaboration between archaeologists, geneticists and the wider heritage sector represented by museums and commercial archaeological organisations. As such, it has formed a powerful vector for the dissemination of knowledge and understanding of cutting-edge scientific approaches to the human past. Our work on long-term population history has generated new insights into the complex inter-relationships between past communities in Europe, prompting fresh perspectives on national identities and new understandings of the fluidity, diversity and mobility of European populations.
Our overall objectives were:
1: To establish the patterning of genetic diversity across Iron Age Britain and to examine the extent to which this corresponds with (a) traditional cultural boundaries, identified through settlement patterns, material culture and linguistic evidence, and (b) genetic clusters identified from analyses of modern DNA.
2: To examine the degree of mobility and connectivity within Iron Age communities in Britain through a suite of isotopic analyses.
3: To characterise the composition of Iron Age cemetery populations in Britain (as a proxy for living communities) in relation to age, sex, diet, health, disability and social inequality.
4: To identify familial relationships within Iron Age funerary contexts in Britain and the degree to which Iron Age communities practiced matrilocal or patrilocal marriage patterns.
COMMIOS analysed aDNA from c.1200 prehistoric individuals from Britain and adjacent regions, and isotopes from 270 individuals. Around 350 individuals have been directly AMS dated. Analysis focussed on the Iron Age, with a significant Late Bronze Age component, reflecting the growing evidence for the importance of this period as work progressed.
A major achievement has been the discovery of previously unknown population movements into southern Britain during the Middle‒Late Bronze Age (c. 1400‒1000 BCE), followed by relative genetic stability during the Iron Age (c. 800 BCE‒CE 100) (Nature https://www.nature.com/articles/s41586-021-04287-4(opens in new window)). This had a major genetic impact across southern Britain, with a cumulative replacement of c. 50% of the genome. We also demonstrated a previously unanticipated rise in lactase persistence (the ability of adults to digest milk) c. 1000 years earlier in Britain than in Continental Europe. We have pubished major studies into pathogen DNA (Science https://www.science.org/doi/10.1126/science.adr2147(opens in new window)) and chromosomal abnormalities (Communications Biology https://www.nature.com/articles/s42003-023-05642-z(opens in new window)). Raw aDNA data have been made available through the European Nucleotide Archive, and as a curated dataset and web application (https://www.biorxiv.org/content/10.1101/2025.05.30.657009v1(opens in new window)).
We conducted multi-method analysis (aDNA, isotopes, osteoarchaeology and funerary archaeology) of cemetery populations included sites from the far south (e.g. Worlebury Hillfort, Somerset) to the far north (e.g. Loch Borralie, Sutherand) of Britain. At a broader scale, we advanced method development in lead isotope analysis through the analysis of 275 lead isotope samples, substantially increasing the available dataset for archaeological lead isotope analysis.
We published the first aDNA analysis of Iron Age kinship (Antiquity https://doi.org/10.15184/aqy.2023.2(opens in new window)) followed by a larger study of c.400 individuals from Wetwang Slack, East Yorkshire currently being prepared for publication.
We held three international conference sessions at the European Association of Archaeologists Annual Conference and Theoretical Archaeology Group Annual Conference; three international workshops in York and Bolzano; an international conference in York, attended by the public and heritage professionals; delivered 69 presentations to a variety of audiences; and maintained a project website (https://commiosarchaeology.com/(opens in new window)) and social media.
A major achievement has been the discovery of previously unknown population movements into southern Britain during the Middle‒Late Bronze Age (c. 1400‒1000 BCE), followed by relative genetic stability during the Iron Age (c. 800 BCE‒CE 100) (Nature https://www.nature.com/articles/s41586-021-04287-4(opens in new window)). This had a major genetic impact across southern Britain, with a cumulative replacement of c. 50% of the genome. We also demonstrated a previously unanticipated rise in lactase persistence (the ability of adults to digest milk) c. 1000 years earlier in Britain than in Continental Europe. We have pubished major studies into pathogen DNA (Science https://www.science.org/doi/10.1126/science.adr2147(opens in new window)) and chromosomal abnormalities (Communications Biology https://www.nature.com/articles/s42003-023-05642-z(opens in new window)). Raw aDNA data have been made available through the European Nucleotide Archive, and as a curated dataset and web application (https://www.biorxiv.org/content/10.1101/2025.05.30.657009v1(opens in new window)).
We conducted multi-method analysis (aDNA, isotopes, osteoarchaeology and funerary archaeology) of cemetery populations included sites from the far south (e.g. Worlebury Hillfort, Somerset) to the far north (e.g. Loch Borralie, Sutherand) of Britain. At a broader scale, we advanced method development in lead isotope analysis through the analysis of 275 lead isotope samples, substantially increasing the available dataset for archaeological lead isotope analysis.
We published the first aDNA analysis of Iron Age kinship (Antiquity https://doi.org/10.15184/aqy.2023.2(opens in new window)) followed by a larger study of c.400 individuals from Wetwang Slack, East Yorkshire currently being prepared for publication.
We held three international conference sessions at the European Association of Archaeologists Annual Conference and Theoretical Archaeology Group Annual Conference; three international workshops in York and Bolzano; an international conference in York, attended by the public and heritage professionals; delivered 69 presentations to a variety of audiences; and maintained a project website (https://commiosarchaeology.com/(opens in new window)) and social media.
COMMIOS has enabled progress beyond the state of the art in the following ways:
1. Our discovery of previously unknown population movements into southern Britain during the Middle‒Late Bronze Age, followed by relative genetic stability during the Iron Age. This demographic shift resulted in a c. 50% genetic turnover in southern Britain with major implications for future studies of cultural and linguistic change. This was the largest aDNA study published at that time, increasing data from the Middle to the Late Bronze Age and Iron Age in Britain by 12-fold, and western and central Europe by 3.5-fold.
2. We discovered a major rise in the allele conferring lactase persistence a millennium earlier in Britain than in Continental Europe, suggesting different selection regimes related to distinct economic and/or cultural differences in the use of dairy products. This has significant implications for understanding the evolutionary history of prehistoric populations in Britain and for archaeological investigation of economic strategies related to pastoralism.
3. We identified unilineal kinship practices at Britain’s largest Iron Age cemetery, Wetwang Slack, East Yorkshire, based on genome-wide analysis of c.400 inhumations. Exceptional levels of biological relatedness enable us to reconstruct detailed pedigrees spanning ten generations, where the primary principle is matrilineal descent represented within burials clusters across the cemetery. Matrilineal societies have not been previously demonstrated in European prehistory and have major implications for our social and cultural interpretations of the period more broadly.
4. We identified previously unsuspected patterns of mobility and connectedness between communities across different parts of Iron Age Britain. This has derived from a combination of methods including isotope analysis, funerary archaeology, osteoarchaeology and aDNA analysis, the latter specifically relating to our implementation of IBD (Identity by Descent) analysis; a technique that has become available over the course of the project.
1. Our discovery of previously unknown population movements into southern Britain during the Middle‒Late Bronze Age, followed by relative genetic stability during the Iron Age. This demographic shift resulted in a c. 50% genetic turnover in southern Britain with major implications for future studies of cultural and linguistic change. This was the largest aDNA study published at that time, increasing data from the Middle to the Late Bronze Age and Iron Age in Britain by 12-fold, and western and central Europe by 3.5-fold.
2. We discovered a major rise in the allele conferring lactase persistence a millennium earlier in Britain than in Continental Europe, suggesting different selection regimes related to distinct economic and/or cultural differences in the use of dairy products. This has significant implications for understanding the evolutionary history of prehistoric populations in Britain and for archaeological investigation of economic strategies related to pastoralism.
3. We identified unilineal kinship practices at Britain’s largest Iron Age cemetery, Wetwang Slack, East Yorkshire, based on genome-wide analysis of c.400 inhumations. Exceptional levels of biological relatedness enable us to reconstruct detailed pedigrees spanning ten generations, where the primary principle is matrilineal descent represented within burials clusters across the cemetery. Matrilineal societies have not been previously demonstrated in European prehistory and have major implications for our social and cultural interpretations of the period more broadly.
4. We identified previously unsuspected patterns of mobility and connectedness between communities across different parts of Iron Age Britain. This has derived from a combination of methods including isotope analysis, funerary archaeology, osteoarchaeology and aDNA analysis, the latter specifically relating to our implementation of IBD (Identity by Descent) analysis; a technique that has become available over the course of the project.