Via The Atlantic

Seven thousand years ago, in a valley that is today central Germany, a young man laid down to die. He was 25 or 30, and a farmer most likely. It is not known why he died young. But powerful genetic tools have now pulled out a tantalizing clue: the fragmented DNA of a virus that infected his liver all those millennia ago.

It is the oldest virus ever directly sequenced, opening up a new window onto prehistory. For the past decade or so, ancient human DNA from millennia-old teeth and bones has been revolutionizing the study of the past. More recently, DNA from ancient bacteria—such as leprosy and plague—in those same teeth and bones has done the same for the study of past epidemics. Viruses were always the next logical step. But their genomes are small and sometimes structured in a way that does not hold up well over time.

Until this week, no one had directly sequenced a virus more than a few hundred years old. And now—as a testament to how quickly the field of ancient DNA is moving—not one but two separate research groups report finding hepatitis B viruses in teeth several millennia old in Eurasia.

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