The movie Gladiator depicted the story of gladiators who fought in the Colosseum during the golden age of the Roman Empire. Gladiators were selected from various regions conquered by the Roman Empire, including York in present-day England, where slave gladiators competed in the 2nd to 4th centuries. Among the gladiators and Roman soldiers who fought at that time, one in four were from the Scandinavian Peninsula. This means that Scandinavian immigrants had already settled in the region before the Anglo-Saxons and Vikings settled in present-day England. Centuries later, during the Viking Age, Scandinavian immigrants raided across Europe and expanded in various directions. Some ventured far beyond Western and Southern Europe into Russia and Ukraine.
Scientists and historians have succeeded in tracing the origins of historical migrations in Europe during the first millennium of human history (1-1000 A.D.) by analyzing genetic changes that occurred over a short period. A research team from the Francis Crick Institute in the United Kingdom, University College London, RIKEN in Japan, and Uppsala University and Stockholm University in Sweden announced on the 1st (local time) that they confirmed concrete evidence supporting historical events of human movement in Europe from 500 B.C. to 1000 A.D. by analyzing genomic samples obtained from the graves of ancient Europeans in the international journal Nature.
◇Reconstruction of historical details of genetic changes over centuries
Europe experienced a tumultuous period during the first millennium of human history. The Roman Empire, which ruled extensive territories from the Iberian Peninsula to Central Europe, and from Mesopotamia to North Africa, fell, leading to invasions by barbarians and Islam, resulting in the establishment of numerous feudal kingdoms. The Byzantine Empire rose in Eastern Europe, while the Holy Roman Empire emerged in Western Europe. During this period, a massive wave of migration occurred across Europe.
Humans tend to be closer the more genetic mutations they share. Groups with the same ancestors inherit the same mutated DNA. Scientists have utilized this point to track significant changes in DNA that occur over thousands or millions of years. Through this process, they have been able to determine how humans evolved differently from monkeys. Scientists say that by following DNA, they can also trace the path of human migration.
However, identifying genetic changes that occurred over shorter periods is very challenging. Tracking through shared haplotypes and rare mutations has limitations in reconstructing events that took place over centuries. In cases like Europe, where ancestors are genetically close, tracing migration routes becomes very difficult.
Human genetic data is extremely vast. The human genome consists of 3 billion base pairs that were completed over a long period. Finding small genetic changes that occurred over just a few generations after a migrant arrived at a new settlement and mingled with natives is like finding a needle in a haystack.
The research team solved the problem by ignoring previously identified genetic changes and focusing only on the most recent changes. This method, called Twigstats, is akin to clearing away the sand and leaving only the needle.
The researchers explored thousands of genomic materials in databases to see how closely related they were genetically. They identified which genes came from which groups and when. In this way, the research team constructed family trees of groups that exhibited new genetic changes during the first millennium. They explained that this method allows for a tenfold clearer distinction even among groups that are genetically very close.
Using this method, the research team examined 1,556 genomes obtained from the graves of ancient Europeans who lived from 500 B.C. to 1000 A.D. According to historical records, this period is divided into the Iron Age (300-800 A.D.), the fall of the Roman Empire, and the 'Great Migration' of the early Middle Ages and the Viking Age. During the first half of the millennium, the Germanic tribes constantly caused disturbances at the northern borders of the Roman Empire. The researchers found genetic traces of groups that migrated southward from northern Germany and Scandinavia during this period. Genes from ancestors of the Germanic peoples were found in southern Germany, Italy, Poland, Slovakia, and southern England.
In Southern Europe, 100% Scandinavian migrants were also found. As the latter part of the millennium progressed, most Scandinavian immigrants who moved into Europe vanished. This indicates that many of the migrants mixed with the natives living in the area. Separately, it has also been newly revealed that around 800 A.D., residents of Scandinavian descent from Central Europe lived in the Scandinavian Peninsula.
◇Vikings already active in England ruled by the Roman Empire
The origins of gladiators active in the outskirts of the Roman Empire have also been revealed. The Roman Empire conquered the island of Britain, now present-day England, around the 1st century and ruled until the 4th century. The researchers confirmed that 25% of the Roman soldiers and slave gladiators active in York during this time were from Scandinavia.
Traces of Europeans who migrated to Scandinavia just before the Viking Age were also discovered. The researchers confirmed that the owners of graves buried on Öland Island in the Baltic Sea had ancestors from Central Europe. This suggests that Central European immigrants had already settled in Scandinavia before the Vikings invaded Europe, according to the researchers.
The researchers speculate that the unstable environment in Scandinavia may have facilitated people's migrations. However, they believe that more archaeological, genetic, and environmental data are needed to clarify the reasons why ancestors of Europeans migrated to Scandinavia.
The researchers also discovered Viking-era DNA in Russia and Ukraine that shares common ancestry with present-day Swedes. Remains found in British graves showed signs of violent deaths along with evidence of genetic connections to Scandinavia. Historians speculate that the owners of these graves might have been Viking raiders who were executed.
◇Adding genetic evidence to historical records
By around 1000, when the full-fledged Middle Ages began, Europe entered a period of stability after invasions and wars ended. Scientists evaluate that this study provides a very sophisticated insight into the genetic history of Northern and Central Europe, from the Iron Age to the later Viking Age.
Leo Späidel, the first author of the study and a researcher at the Francis Crick Institute, noted, “Analysis of human migration and population changes over time has generally been ambiguous,” adding, “The new analytical method will help find more pieces of the puzzle that have been missing from history.” Pontus Skoglund, the corresponding author and group leader at the ancient genomics laboratory of the Francis Crick Institute, stated, “This new analytical method provides a sharper lens for small-scale history and aims to uncover historical facts that were previously unanswered by expanding the records of ancient whole-genome sequences.”
The scientific community believes the new analytical method can provide scientific evidence for historically ambiguous events. Records of what happened around the time when the ruling power in Britain changed from the Romans to the Anglo-Saxons are unclear. Historians also have varying assessments of this period. Similarly, the reason why power shifted from the Slavic people in Central and Eastern Europe during the same period remains a mystery.
Historians believe the new analytical method will be useful for confirming whether historical records align with the facts. They also assert that when historical records and discovered results do not match, it can provide scientific and concrete grounds for establishing new historical theories. Scientists evaluate that historians now have an innovative tool that will intricately support the specific events they research.
Peter Heather, a medieval history professor at King's College London and a co-author of the study, stated, “Despite historical records indicating that migrations in Europe around A.D. 1000 restructured the population of Eurasia and shaped political and cultural identities in Europe, there has always been intense debate over details such as the scale and trajectory of these migrations.” He added, “The new analytical method has opened up possibilities for resolving these issues.”
References
Nature (2025), DOI: https://doi.org/10.1038/s41586-024-08275-2