Who brought down Rome? Few questions vex historians as much as the identity of the invaders who transformed the last vestiges of the great empire into a series of warring medieval territories. Was it long-distance migrants, the infamous barbarian hordes? Or was it diverse, local militias who moved to fill the power vacuums left by the diminished capital? Both?
This is not a question typically asked in these pages — historians have their own meetings and journals, after all. But as scholars continue to discuss the past, a new breed of scientists is trying to muscle in on the work of the present. These researchers want to use modern genetic techniques to answer historical questions, and as they do so, they are firmly treading on the toes of their colleagues in the humanities. These geneticists promise answers: using analysis of DNA to discover what ‘really’ happened during the Bronze Age and the Viking sagas and replace ‘biased’ histories with cold, hard data.
Not all historians are embracing this new world. Many such studies, they complain, take a ‘sequence first, historicize later’ approach, in which researchers discover some shift in the genetic make-up in the inhabitants of a region, for example, and then postulate a historical event that might be responsible for the demographic change.
Some historians and linguists felt uneasy about papers published in this journal last year that found similarities between the genomes of people living on the Russian steppe 5,000 years ago and in Western Europe 4,500 years ago. The studies speculated that this correlation was the result of a massive migration to Europe of steppe people who also imported Indo-European languages, a family that includes nearly every dialect spoken on the continent (see Nature 522, 140–141; 2015).
So, one might expect historians to be hostile to the latest sequencing effort. It aims to analyse DNA from 1,100 sets of ancient remains from across Italy, Austria, Hungary and the Czech Republic, to work out who filled the void left by the fall of the Roman Empire — or at least how the empire turned into the Lombard kingdom, which ruled parts of Italy between the sixth and eighth centuries ad.
Yet among the project leaders is a card-carrying medieval historian. Patrick Geary at the Institute for Advanced Study in Princeton, New Jersey, has shaped the questions that the project will tackle and how they will be asked. His colleagues must fight for the soul of their field before it is cannibalized, Geary argues. “If historians do not get involved and engage with this technology seriously, we’re going to see more and more studies that are done by geneticists with very little input from historians, or from frankly second-rate historians,” he says.
“Historians will be left behind if they fail to incorporate genetics into their research.”
This week, he will lead a workshop that will gather 20 or so early-career historians and archaeologists at the Max Planck Institute for the Science of Human History in Jena, Germany, to learn about ancient DNA and other quantitative tools that are disrupting how scholars probe the past.
Among the issues niggling at historians is the concern that an individual’s genetic make-up might be used interchangeably with his or her ethnic identity. Historians prefer to see ethnic groups, such as Anglo-Saxons or Franks, as fluid categories that involve identifying with one group while rejecting others. As such, the Lombard sequencing effort will not use DNA to define a genetic profile of the kingdom’s founders, but to ask nuanced questions about migration, continuity between earlier and later inhabitants, and whether their ancestry relates to how and where they were buried.
Other efforts to get geneticists and historians speaking the same language are under way. A consortium led by ancient-DNA researcher Hannes Schroeder, at the University of Copenhagen, recently won a €1.2-million (US$1.3-million) grant for a collaborative research project called CITIGEN to make his field more accessible to historians and other humanities scholars. Like Geary, Schroeder worries that historians will be left behind if they fail to incorporate genetics into their research. “The train is running, and you jump on it or you miss it,” says Schroeder, who is also involved with an effort using ancient DNA to study the transatlantic slave trade.
The young historians and archaeologists who will get their first taste of molecular genetics this week will hopefully come away with a new tool to bring to their research. But they should be prepared — not just to understand genetics enough to read a paper, but to challenge insights gleaned with ancient DNA and to shape how the technology is used to interpret the past. After all, there are barbarians at the gates.
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