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.