In the Roman era of Britain, the island was inhabited by Celtic-speaking Britons. By the 7th century, a huge portion of Britain was inhabited by Germanic-speaking Anglo-Saxons. How did this massive shift happen? While the traditional narrative explains that the Anglo-Saxons invaded from the continent en masse, scholars in recent decades have generally favored a less dramatic explanation. It has been popular to argue that relatively few Germanics actually arrived in Britain and that the Britons willingly adopted the culture and language of the Anglo-Saxons. What does new genetic research reveal about this controversy?Traditional vs Revised Review of the MigrationAnglo-Saxon Homelands and Settlements. Source: Wikimedia CommonsTo understand the significance of this new genetic research, we need to understand the controversy about the Anglo-Saxon migration. According to medieval sources, the Britons sought help from Germanic mercenaries after the end of the Roman era. This arrangement soon broke down, leading to the Anglo-Saxons to begin invading en masse. This large-scale invasion from the continent took place over generations, continuing well into the 6th century. They slaughtered innumerable Britons, driving them out of their home territory. The Britons were pushed to the west, eventually becoming confined to Wales and the West Country.However, due to a lack of clear archaeological evidence for extensive violence and destruction in this era, many scholars throughout the 20th century turned away from this traditional narrative. They began viewing the emergence of the Anglo-Saxons in Britain as a case of semi-peaceful migration and an exchange of culture. Some extreme minimalists essentially denied that any Anglo-Saxon migration occurred at all.Previous Genetic StudiesMap of the population of Britain divided by DNA, from Leslie et al, The Fine Scale Genetic Structure of the British Population, Nature, 2015. Source: National Library of MedicineWith the advent of new technology, it was thought that genetic studies could settle the matter. By looking at the DNA of the population of England and comparing it with the population of Wales and Germany, this would supposedly reveal how significant the Anglo-Saxon migration was. If the DNA of the English only had a small amount of German DNA, being predominantly similar to Welsh DNA, then this would prove that the Anglo-Saxon migration was a very small event. In contrast, if the DNA of the English was more similar to the Germans than to the Welsh, then this would demonstrate that a sizable number of Anglo-Saxons must have replaced the natives. At least, this was the theory. As scientists performed such studies, what did they find?A notable study from 2015 by Leslie et al found that the percentage of Germanic ancestry, attributable to the Anglo-Saxons, among the modern English was between 10 and 40 percent. This suggested that the Anglo-Saxon migration was not nearly as large as the medieval sources implied.Photo of a large Anglo-Saxon burial ground in Buckinghamshire. Source: BBCThe results of this study emboldened those who were driven by the apparent lack of archaeological evidence for violence to argue that the Anglo-Saxon migration was a very limited event. This seemed to support the viewpoint that the emergence of Anglo-Saxon England was predominantly the result of native Britons adopting the culture and language of a small number of Germanic arrivals.However, a big problem with studies of this nature is that they are, of course, based on modern populations. The following year, a study was performed that looked at evidence from early medieval burials. They sequenced the genomes of individuals whom they believed to be Anglo-Saxons and used that as a basis for comparison with modern populations. Interestingly, the evidence found in this 2016 study largely corroborated that of the earlier one. The researchers found that the modern population of eastern England had a range of 25-50 percent Saxon DNA. This, again, suggested that the Anglo-Saxons were always the minority in their territory.A Landmark Genetic StudyThe temporal and geographic origin of the individuals included in the study, in Gretzinger et al The Anglo-Saxon Migration and the Formation of the Early English Gene Pool, Nature, 2022. Source: NatureThis same trend continued in 2020, with another study comparing medieval DNA to modern populations. This study found that only 31 percent of the DNA of the modern English comes from the Anglo-Saxons.However, this all changed in 2022. This study, led by J. Gretzinger, D. Sayer, and P. Justeau and published in Nature, analyzed thousands of ancient and medieval samples from Europe and England, covering the period from 200 to 1300 CE. This enabled the researchers to see clearly how many Anglo-Saxons migrated to Britain in the post-Roman era. They did not have to rely on studying modern populations and hoping that these populations preserved the medieval percentage of Germanic DNA.The results of the study were striking. The researchers found that there was evidence of substantial migration from across the North Sea, the continental home of the Anglo-Saxons, into Britain. With this new evidence, there is no doubt at all that the Anglo-Saxon migration was a major event.Re-enactment group as Anglo-Saxon warriorsAccording to the researchers:We identify a substantial increase of continental northern European ancestry in early medieval England, which is closely related to the early medieval and present-day inhabitants of Germany and Denmark, implying large-scale substantial migration across the North Sea into Britain during the Early Middle Ages. As a result, the individuals who we analysed from eastern England derived up to 76% of their ancestry from the continental North Sea zone.Of course, not all regions of England showed such high percentages. Nevertheless, the researchers note the following:Our results overwhelmingly support the view that the formation of early medieval society in England was not simply the result of a small elite migration, but that mass migration from afar must also have had a substantial role.The significance of this genetic study on the controversy surrounding the Anglo-Saxon migration is immense. It has demonstrated that the minimalist viewpoint is wrong, and even the more centralist viewpoint is no longer tenable.What Does This Genetic Evidence Mean for the Anglo-Saxons?Anglo-Saxon grave containing a woman cradling a baby, Lincolnshire Wolds, c. 5th or 6th century. Source: BBCHowever, this genetic study does not necessarily mean that the traditional description of the Anglo-Saxon migration is accurate. According to the traditional view, not only was there a mass migration, but the Anglo-Saxons violently invaded and conquered the land of the native Britons. The two peoples did not peacefully integrate with each other.What does the evidence from the genetic study reveal about this aspect of the Anglo-Saxon migration? Is there any evidence that it was a violent invasion, or was it a semi-peaceful migration?One key finding of this study was that there were just as many women who migrated to Britain as men. Some news outlets attempted to portray such a finding as evidence that this was not a violent invasion. According to their logic, only a male-dominated immigrant population would indicate such a thing. However, when we look at the evidence from medieval sources more closely, we can see why this argument is not in harmony with the facts.A depiction of Bede, one of the medieval historians who fought about the Anglo-Saxon invasion, Gloucester Cathedral. Source: Wikimedia CommonsThe medieval sources always portrayed the Anglo-Saxons as invading for the purpose of conquering new land for their families to live in. It was not the case that they were conquering new territory to impose tribute on subject peoples, like the Romans. Rather, they had every intention of actually living in the new land that they were conquering. This is what the medieval sources tell us. Hence, the fact that we find just as many women as men migrating over to Britain in the post-Roman era is not in any way inconsistent with the tradition of violent migration.Nevertheless, what the study does prove is that the Anglo-Saxons did not entirely replace the local population. Even within individual settlements, the researchers often found that both entirely foreign and entirely local individuals were present together. In some places, there is evidence for social separation, whereas in others, there is not.Yet this, too, does not in the slightest suggest that there was not a violent invasion. After all, the Romans violently invaded Britain yet never even came close to wiping out the local population in any area.What Genetic Studies Show About the Anglo-Saxon MigrationInvaders crossing the sea to Britain, Pierpont Morgan Library MS M.736, folio 9v, c. 12th century. Source: Morgan Library and MuseumIn conclusion, what do modern genetic studies show about the Anglo-Saxon migration? Over the past ten years, there have been a variety of studies primarily using modern DNA. These studies suggested that the Anglo-Saxons only ever comprised a minority of the population inhabiting England. However, the most recent major study on the matter, from 2022, has completely overturned this viewpoint. This study has demonstrated that there was indeed a mass migration of Germanics from across the North Sea. In eastern England, the percentage of Germanic DNA on average was as high as 76 percent.Of course, there are some things that this study cannot reveal. For example, it cannot reveal how violent this process was. Nevertheless, it seems unlikely that such a large population displacement could have occurred without violence, given the inevitable struggle over resources. This study reveals that there was plenty of integration between the locals and the new arrivals, but it does not reveal whether this was forced or by choice.Despite the unanswered questions, this study has provided profoundly important information regarding the true nature of the Anglo-Saxon migration.