The weapons in two Viking-style graves on Orkney suggested a familiar Norse setting. Their DNA complicated that picture. In the 2020 study of Viking Age genomes, these men, buried off the northern Scottish coast, showed closer genetic affinities to people in the British Isles than to the Scandinavian populations used for comparison. Swords and other burial customs placed them within a Norse cultural world, although their ancestry did not match what archaeologists once might have assumed from those objects. The contrast warns against inferring ancestry directly from burial objects.
The Viking Age is usually placed around 750 to 1050 CE. During those centuries people travelling from what are now Denmark, Norway and Sweden raided, traded, established settlements and entered military service around Europe and the North Atlantic. They did not form one people with identical ancestry, livelihoods or political loyalties. Many Scandinavians never took part in the maritime expeditions for which the period is named. Genetic evidence becomes easier to interpret when the Viking Age is understood through those activities and connections, rather than as the history of one biological population.
Written chronicles, place names and grave goods can trace parts of that history, but ancient DNA brings different information. Researchers can identify biological relatives, compare people interred at distant sites and examine ancestry entering or leaving a region. A genome cannot tell us what someone called themselves, which language they spoke, or why a weapon accompanied them into a grave. Nor can it make an archaeological interpretation unnecessary. The strongest interpretations test the genetic findings against surviving objects and written accounts.
The 442 genomes that changed the picture
An international team led by Ashot Margaryan published Population genomics of the Viking world in Nature in September 2020. Eske Willerslev was among the senior researchers, and the project involved geneticists working with historians and archaeologists. They sequenced material from 442 ancient people discovered in Europe and Greenland. Most belonged to the Viking Age, but individuals from before and after that period allowed the team to compare populations over time. The breadth of the samples across places and centuries allowed comparisons beyond individual cemeteries.
The genomes revealed differences within Scandinavia long before any simple picture of a united population could hold. They also indicated the arrival of ancestry from other parts of Europe before and during the Viking Age. Among people who travelled outwards, the researchers found broad regional patterns: Danish-related ancestry in England, Swedish-related connections toward the eastern Baltic, and Norwegian-related connections toward Ireland, Iceland and Greenland. These geographical patterns describe statistical similarities among the ancient people sampled. Such results cannot give every person a birthplace, a nationality or a straightforward record of their travels.
Those regional labels require historical context. Denmark, Sweden and Norway were not bounded nation-states with stable modern identities in the ninth century. Their rulers held shifting territories, while relatives and trading partners maintained links far beyond any ruler’s control. In genetic papers, ‘Danish-related’ refers to a resemblance to genomes sampled from part of ancient Scandinavia. It is possible for someone with that resemblance to have grown up elsewhere and never to have thought of themselves as Danish. The genetic comparison cannot establish an individual’s birthplace or sense of identity.
The Orkney burials show how easily these categories become confused. Their weapons and funeral arrangements were recognisably Norse, while the DNA resembled ancestry found among nearby British populations. The men might have spoken Norse or belonged to families integrated into a Norse community; the burial customs might also have been chosen by those who commemorated them. No grave can settle all of those possibilities. What the evidence does establish is that Scandinavian-style material culture and Scandinavian ancestry should not be treated as interchangeable categories.
Ancestry can mislead in the opposite direction as well. A person with ancestry linked to Scandinavia may never have raided a monastery, traded furs or sailed to England. The label ‘Viking’ refers in many contexts to an activity, or to the wider society in which such activities occurred. A genome is evidence about biological descent. Genetic evidence lets historians investigate descent separately from the occupations, cultural affiliations and social roles they must reconstruct through other sources.
How scientists recover DNA from Viking Age skeletons
Ancient DNA rarely survives intact. Centuries of moisture, heat, microbial action and burial chemistry leave it broken into short pieces, sometimes too damaged for useful analysis. Scientists often take samples from teeth or the petrous portion of the temporal bone, the exceptionally dense bone surrounding the inner ear. That area can protect concentrations of human DNA better than other parts of a skeleton. Even a bone that appears well preserved may contain too little ancient DNA for analysis.
Modern DNA is an immediate danger during excavation and analysis: anyone handling a skeleton can contaminate the sample. Ancient-DNA laboratories therefore employ controlled workspaces, clean equipment and surfaces, and extraction controls that help identify contamination. After carefully powdering a little tooth or bone, researchers recover fragments, prepare sequencing libraries and compare the resulting sequences with a reference genome. Laboratories may choose different treatments to remove contamination or prepare libraries, so there is no single cleaning procedure common to every study. The safeguards used to authenticate and process samples matter when assessing a published result.
Researchers look for several signs that the recovered material is genuinely ancient. Fragments are generally short, and their ends can show characteristic chemical damage, notably apparent cytosine-to-thymine changes. They also consider contamination estimates, the distribution of fragment lengths, agreement between independent extractions and the archaeological setting. A recent review of ancient-DNA methods explains the methods and their limits. Weak damage patterns do not necessarily invalidate a sample: laboratory treatment may have removed damaged bases, and unusually good preservation can produce different results.
After authentication, researchers analyse patterns of similarity across genomes. Analysts compare thousands of positions across ancient and reference genomes to assess genetic similarity and test models of shared ancestry. Principal component analysis can display clusters of resemblance, though those clusters shift with the comparison groups selected. Another tool, qpAdm, assesses proposed ancestry mixtures under defined source choices and assumptions. These methods help reconstruct population movement, but cannot establish where a particular person was born.
Close family relationships can sometimes be established more directly. Brothers, for example, share lengthy stretches of DNA inherited through recent ancestors. The same approach can identify relatives in one cemetery or link people buried hundreds of miles apart. The relationship established by DNA is biological. Knowing two people were closely related says nothing by itself about their feelings, whether they shared a household, what position either held or what circumstances separated their graves.
The routes from Scandinavia were different from one another
Viking Age journeys followed different routes, shaped by geography and existing trading networks. Across the North Sea, communities in the Danish region were connected with English settlements and kingdoms. Western routes linked the Norwegian coast with Scotland, Ireland and islands farther into the North Atlantic. In the east, seafarers, traders and armed groups travelled through the Baltic and the rivers of eastern Europe toward the Black Sea and Byzantine territories. Written testimony, objects and place names already revealed these connections. The 2020 genomic study added evidence about which movements left traces in the ancestry of buried populations.
Scandinavian activity in England unfolded over several generations. Raids began in the late eighth century, larger armies campaigned and wintered there in the ninth, and Scandinavian political authority and settlement subsequently developed at different rates across areas later known as the Danelaw. Some ancient English burials show affinities with southern Scandinavia, consistent with movement across the sea. But those graves cannot tell us how many people joined an army, how quickly a family adopted English, or whom individual settlers married.
Eastern routes brought Scandinavian-associated travellers into regions where trade and politics already involved many peoples. The Rus, known from later written accounts, participated in river commerce, warfare and the formation of states. Scandinavian-related ancestry in an eastern European grave provides evidence of population movement. The identity of the Rus and their political development must also be studied through written and archaeological sources. Settlers in Iceland and Greenland likewise included people with connections to Scandinavia without thereby forming populations of uniform ancestry.
Scandinavia was itself receiving newcomers. The 2020 study found ancestry moving in from the south and east, while a 2025 study by Leo Speidel and colleagues examined the longer pattern using Twigstats, a finer-scale method applied to 1,556 previously published ancient genomes. The team identified a substantial contribution related to Iron Age central European populations among Viking Age inhabitants of southern Scandinavia, with important differences between regions. The ancient comparison groups remain too limited to name a precise homeland for every contribution. An ancestry shift visible by about 800 CE cannot automatically be assigned to a particular invasion mentioned in chronicles.
The 2025 analysis also revised estimates of ancestry entering Scandinavia from Britain. Earlier models had probably overstated some proportions because British and continental populations were closely related and difficult to distinguish statistically. The new method suggested a more discriminating reading of the data, though movement across the North Sea remained evident from other sources. These changes to estimated ancestry proportions do not overturn the independent archaeological evidence for voyages and contact.
Iceland’s founders and the people who crossed the North Atlantic
Iceland’s settlement brought together people with different ancestral backgrounds. Conventionally, its settlement begins in the late ninth century. Medieval Icelandic narratives emphasise settlers from Scandinavia, but genetic findings and archaeological evidence also point to ancestors from Ireland and Britain. Their journeys did not necessarily happen under the same circumstances. Some people travelled freely, while others may have been moved through coercion or enslavement. No individual’s genome records which of those experiences brought them to the island.
In 2018, S. Sunna Ebenesersdóttir and colleagues published a study of 27 ancient Icelanders in Science. Their analysis identified people with Norse ancestry, Gaelic ancestry and combinations of the two. Ancient Icelanders were often genetically closer to the source populations of their ancestors than living Icelanders are today. Subsequent genetic drift and the unequal survival of different ancestral lines help account for that difference. Drift is the random change in the frequency of inherited variants, an effect that can be particularly pronounced in a comparatively small founding population.
Studies of the Y chromosome and mitochondrial DNA have also suggested different contributions from Scandinavian men and women with ancestry in the British and Irish Isles. The Y chromosome tracks one paternal line, while mitochondrial DNA generally tracks one maternal line. Each marker follows one ancestral line among many. Chance, the samples selected and later changes in population size can all affect their distribution. Neither marker provides a full account of marriages, migrations or personal circumstances across the settlement generations.
The combined evidence points to mixed communities from Iceland’s early settlement period. It gives no grounds for declaring every woman with Gaelic ancestry a slave, or every man of Scandinavian ancestry a conqueror. Arguments about enslavement and status need evidence from history and archaeology as well. Ancestry also did not predetermine the settlers’ descendants’ language. Iceland developed an Old Norse literary tradition among people whose ancestors came from several parts of the North Atlantic.
Norse Atlantic journeys reached as far as Newfoundland. Excavations at L’Anse aux Meadows have revealed Norse-style buildings and work that included woodworking and iron production. A 2021 dendrochronological and radiocarbon study established that wood was worked there in 1021 CE, using a radiocarbon anomaly in conjunction with tree-ring counting. The dated wood provides unusually precise evidence of a Norse presence in North America. The date was established through wood and radiocarbon science, not by finding a Viking genome on the continent. The settlement and its precise date are established through material and chronological evidence, independently of genetic analysis.
Birka Bj 581: DNA, a weapon burial and a long argument
In Sweden, the trading centre of Birka stood on Björkö in Lake Mälaren. In 1878, Hjalmar Stolpe excavated a furnished grave beside a fortified area that came to be known as Bj 581. It contained horses, gaming pieces and an extensive collection of weapons: a sword, spear, axe, arrows and shields. The occupant was long assumed to have been a male warrior because of those grave goods, despite later osteological work suggesting the skeleton was female. That interpretation rested largely on the expectation that a weapon-filled grave belonged to a man.
Charlotte Hedenstierna-Jonson and fellow researchers published genomic results from a tooth and an arm bone in 2017. Sequences from X and Y chromosomes supported the identification of the buried individual as biologically female. The team also analysed strontium isotopes in teeth, a separate line of evidence relevant to movement during childhood. Local geological signatures pass into food and drinking water and into teeth as they form. Comparing those signatures with the burial region can suggest whether someone grew up elsewhere, although different areas may produce similar measurements and cannot always be distinguished.
Identifying a biological female in the Birka grave did not determine what she did during life. Weapons and gaming pieces formed an exceptional martial assemblage, but the grave can support several interpretations: active fighter, leader, member of a military household or someone honoured through symbolic objects. Gaming pieces could signify strategy but cannot prove command; the presence of weapons likewise does not establish whether the occupant used them. These questions concern the social meaning of the burial rather than the genetic identification of its occupant.
A 2019 Antiquity reassessment considered objections to the earlier findings and returned to the grave’s archaeological setting. The authors supported the warrior interpretation by considering the burial assemblage, its position and the results from the bones and DNA together. There is still room to debate the precise role of the dead person. Yet the traditional assumption that the occupant must have been male because weapons lay in the chamber cannot survive the independent biological evidence. Neither category of evidence alone settles the deceased person’s role.
Brothers buried in Estonia and relatives separated by the North Sea
At Salme on Estonia’s island of Saaremaa, archaeologists uncovered eighth-century ship burials containing men killed violently. The 2020 genetic study identified four brothers buried in one vessel. Their biological kinship is a firm result, while the wider assemblage suggests an expedition connected with armed conflict. The shared burial makes a common violent episode likely. But DNA cannot reveal whether the brothers died on one day, joined willingly, followed a particular leader or lived together before the voyage.
The same study connected a burial in Denmark with one at Oxford in England through a second-degree biological relationship. That degree of kinship covers more than one family arrangement, including some cousins, uncles and nephews, and other relatives separated by two meioses in a pedigree. Without additional evidence the individuals cannot be assigned a precise family label. The result places closely related people in graves on opposite shores of the North Sea.
The Salme brothers and the Denmark-Oxford relatives suggest that kin could move within military and trading routes. They do not establish that every expedition was made up of family members. Ships needed crews, merchants relied on contacts and leaders recruited followers who might be relatives or strangers. Genetic analysis reveals connections among the people whose remains survive. To understand how those ties functioned in life, historians still need graves, written accounts and comparisons with other communities.
Ports and market towns such as Ribe, Hedeby, Birka and Kaupang drew people and goods from distant regions. Some sampled populations in those centres are genetically varied, which fits the archaeological picture of trade and movement. But a particular ancestry estimate cannot identify an individual’s trade or tell whether they personally migrated. A distinctive genetic profile could belong to a newcomer or to someone born locally whose parents or grandparents moved. Finds from workshops, dwellings and burials are needed to distinguish those histories.
Conversion to Christianity did not leave a simple genetic signature
Christianisation changed Scandinavian society during the tenth and eleventh centuries, although it unfolded differently from region to region. Kings and missionaries promoted Christianity, churches and churchyards became more common, and ecclesiastical institutions increasingly affected marriage, inheritance and relations among kin. The larger Jelling runestone preserves Harald Bluetooth’s claim that he made the Danes Christian. These records document changes in religious practice and institutions. They provide no direct measure of simultaneous changes in ancestry.
The 2020 Viking genome paper cannot be used as proof that Christian marriage rules produced a specific genetic transition. Its questions concerned ancestry, mobility, relatedness and particular variants over long periods. It did not compare pre-Christian and church burial groups under conditions that could isolate the effects of conversion on partner choice. Changes in funerary practice also alter which remains are available for sampling. A dataset may therefore look different because a new kind of cemetery survives, even when the composition of the living population changed far less.
Christianisation shaped community institutions and changed what entered the archaeological record. The Jelling stones, legal texts and excavated churchyards help historians place genetic patterns in their social setting. For the cases discussed here, however, connecting a particular church rule directly to a measured change in ancestry would require evidence that has yet to be shown. Correlation across a period of conversion is not enough to establish that cause.
What Viking DNA can and cannot tell us today
Commercial DNA tests sometimes describe Scandinavian ancestry as proof of a Viking ancestor, although their estimates cannot support that conclusion. Modern reference populations define the categories used by consumer ancestry companies, whereas Scandinavians lived both before and long after the Viking Age. Even a demonstrable biological link to a Viking Age inhabitant would not tell us whether that ancestor joined an expedition, spoke Old Norse or practised a particular religion. Over a thousand years, people acquire enormous numbers of genealogical ancestors, only a fraction of whom leave recognisable DNA segments in a descendant.
Genes can sometimes help researchers estimate the probability of particular pigmentation traits in an ancient individual. The 2020 study examined variants associated with pigmentation as well as immunity and lactase persistence. The results do not justify a single physical portrait of Viking Age populations. Ancestry categories likewise reveal nothing reliable on their own about an individual’s rank, character, behaviour or presumed fixed biological qualities.
The published 442 genomes greatly expanded the evidence, but their distribution is shaped by what survived and what scholars could sample. Soil conditions, burial rites, excavation history, conservation requirements, consent and preservation policy all influence the available graves. Cemeteries serving warriors, elites or religious communities may contribute disproportionately. No map of sequenced Viking Age skeletons can be assumed to show an unbiased cross-section of everybody then alive.
The burial at Repton in Derbyshire illustrates another distinction between methods. A mass burial has been associated with the Viking Great Army, and a 2018 radiocarbon reassessment addressed problems in its chronology. People who ate marine foods can appear artificially old in radiocarbon tests because of the marine reservoir effect. After correcting for that influence, the dates were consistent with a late ninth-century event connected with the army’s wintering in 873–874. Radiocarbon established a stronger chronology, but did not identify every individual’s ancestry or prove that all those buried there belonged to the army.
New statistical tools can change the interpretation of genetic results from the same skeletons. The 2025 Twigstats research revised finer-scale comparisons between closely related European populations and could help future work distinguish continuity from migration in smaller regions. Combined with isotope measurements, dietary evidence and settlement archaeology, more genomes may reveal additional family networks. Such advances also confront the destructive nature of bone sampling, obligations toward descendant communities and the unequal chances that different people’s remains were preserved.
Viking Age genomes give historians evidence for kinship and movement that surviving chronicles and burial objects alone cannot supply. They show people of varied backgrounds sharing settlements, households, towns and routes across the sea. Their results cannot recover why an individual left home, how they understood belonging or how neighbours regarded them. Those remain historical questions requiring the combined testimony of material culture, language, documents and genetics. Together, these sources recover a more detailed history than genetic ancestry alone can provide.
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