There are no signs of a massacre—no mass graves, no piles of bones. Yet more than a million men vanished without a trace. They left no descendants. Historians know that something dramatic happened in England just as the Roman empire was collapsing. When the Anglo-Saxons first arrived in that northern outpost in the fourth century a.d.—whether as immigrants or invaders is debated—they encountered an existing Romano-Celtic population estimated at between 2 million and 3.7 million people. Latin and Celtic were the dominant languages. Yet the ensuing cultural transformation was so complete, says Goelet professor of medieval history Michael McCormick, that by the eighth century, English civilization considered itself completely Anglo-Saxon, spoke only Anglo-Saxon, and thought that everyone had “come over on the Mayflower, as it were.” This extraordinary change has had ramifications down to the present, and is why so many people speak English rather than Latin or Celtic today. But how English culture was completely remade, the historical record does not say.
Then, in 2002, scientists found a genetic signature in the DNA of living British men that hinted at an untold story of Anglo-Saxon conquest. The researchers were sampling Y-chromosomes, the sex chromosome passed down only in males, from men living in market towns named in the Domesday Book of 1086. Working along an east-west transect through central England and Wales, the scientists discovered that the mix of Y-chromosomes characteristic of men in the English towns was very different from that of men in the Welsh towns: Wales was the primary Celtic holdout in Western Britannia during the ascendance of the Anglo-Saxons. Using computer analysis, the researchers explored how such a pattern could have arisen and concluded that a massive replacement of the native fourth-century male Britons had taken place. Between 50 percent and 100 percent of indigenous English men today, the researchers estimate, are descended from Anglo-Saxons who arrived on England’s eastern coast 16 centuries ago. So what happened? Mass killing, or “population replacement,” is one possible explanation. Mass migration of Anglo-Saxons, so that they swamped the native gene pool, is another.
Yet no archaeological or historical evidence from the fifth and sixth centuries hints at the immense scale of violence or migration that would be necessary to explain this genetic legacy. The science hinted at an untold story.
Not only in this instance, but across entire fields of inquiry, the traditional boundaries between history and prehistory have been melting away as the study of the human past based on the written record increasingly incorporates the material record of the natural and physical sciences. Recognizing this shift, and seeking to establish fruitful collaborations, a group of Harvard and MIT scholars have begun working together as part of a new initiative for the study of the human past. Organized by McCormick, who studies the fall of the Roman empire, the aim is to bring together researchers from the physical, life, and computer sciences and the humanities to explore the kinds of new data that will advance our understanding of human history.
In the Anglo-Saxon example, genomic archaeology—a new approach to genetics, demography, and mathematical simulation that uses genomic data from living people to illuminate major events in the past—eventually led to an explanation of how the males in Roman England might have been wiped out. Another study has traced the geographic spread of a gene variant that allows adults to digest the sugar in milk; possessing that allele appears to have conferred a tremendous evolutionary advantage during the last 10,000 years. Isotopic studies of human bone have revealed prehistoric dietary shifts, and shown that Neanderthals were more like us than previously imagined. Reconstructions of ancient mammalian DNA have led to new, climate-related theories about the extinction of megafauna (such as wooly mammoths) in which humans appear less to blame than previously supposed. And innovative technologies allow the identification of hearths and buildings in layers of soil, revealing the presence of entire villages at sites long thought to have been abandoned. The study of the human past, in other words, has entered a new phase in which science has begun to tell stories that were once the sole domain of humanists.
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Irish Tory 
I apologise for the vagueness of the following.
Perhaps a couple of years ago I watched a TV programme on a burial site which had been found on the East coast of England (Suffolk/Norfolk), the area of maximum Saxon and later Danish invasion. The site was PRE SAXON. Enough DNA was recovered to make comparisons with volunteers from today’s local population. The similarity was overwhelming – of the order 80% plus, if I recall aright..
This suggests that Saxon and later invasions were of relatively small scale and that the incomers established overlordship rather as the Normans did later.
Other DNA studies which I have read (but whose titles I have forgotten) suggest that post ice age settlement of Britain came from two main sources. The West (Celtic) side was settled by people from Spain and the South of France who strolled across and up the coast. The Eastern side was settled in a similar way by people originating from Eastern/Central Europe.
I have also read a persuasive case that the people in South Eastern England in Roman times were of the tribe called Belgae by the Romans. Caesar noted that Gaul was divided into three parts but did not mention the language spoken in the Belgic bit. The author pointed out that Anglo Saxon is not very closely related to modern English and thought it was probably only the language of the incomers, just as Norman French became the official language after 1066. Because Anglo Saxon was written, it survived. Nobody ever wrote down Belgic. Latin served as the language of record in the Roman occupation. The Belgae-living-in England during Roman times , he believed, were speaking a sort of proto-English which explains the linguistic affinity with the Friesians. A Flemish newspaper with the title “Het Laatste Nieuws”) demonstrates a close kinship.
The idea of the Anglo Saxons slaughtering their way across to the Welsh border hardened into the received theory in Victorian times and is still very strongly entrenched in people’s minds. It may be due for a rethink.
Thanks for the comment, I seem to remember reading something similar in Blood of the Isles, by Brian Sykes, in it he states that the Mitochondrial DNA in throughout the British Isles has remained largley unchanged since the Neolithic period. Although mitochondrial DNA is from the female side, so it does not preclude invasion by men from different areas, although according to the Seven Daughters of Eve by the same author, most Europeans are intimately related throught both through the female mitochondrial DNA and the Y chromosome.
Apparently DNA studies show Anglo Saxon DNA in England is in the region of about 20%, although it varies by region, in East Anglia it rises to about 50% if I remember correctly!
It is a facinating subject and one not properly understood, which makes it all the more interesting!
I love this topic as well. I’m American, but heavily Irish and Welsh by blood, so I tend to sympathize with the Celts.
It was my understanding, although not widely informed, that the Anglo-Saxon entry was more of a Colonization. Versus the Norman entry which was Conquest.
Stumbled here via tagsurfer at wordpress and zapjens blog. Thankyou for the synopsis and link to a fascinating article. I do not understand all the science involved but the human tale implied is to me compelling stuff.
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