The Vikings buried on the Danish island of Funen may very well have sailed all the way to Constantinople or Baghdad or Moscow, looting and pillaging with lusty ferocity. And now we've got their DNA.

In a study published today in Public Library of Science ONE, Danish scientists describe the retrieval of genetic material from ten Viking skeletons found in an ancient burial site near the city of Odense. The remains date to 1000 AD, the twilight of Viking civilization.

The scientific team was led by the Institute of Forensic Medicine's Jorgen Dissing, who previously showed that the last Viking king was buried with his daughter-in-law, not his mom.

The discovery of the DNA is not in itself extraordinary (though it certainly is cool to have Viking DNA samples). The significance instead lies in the steps the researchers took to keep the DNA free from contamination.

Recovering ancient DNA is a notoriously tricky task. First scientists must find a decently preserved sample. Then they have to keep it from becoming tainted by other genetic material. This isn't easy. Stray DNA is to researchers what dust is to regular people: inevitable and nearly escapable.

That's what spoiled Cretaceous-era dinosaur DNA and Neolithic remains found in Spain. Academic literature is full of reports on promising samples gone bad, or parsing the techniques needed to be sure that ancient DNA doesn't actually come from a stray flake of lab technician skin.

To recover the Viking samples, the researchers took extra-special care.

Before removing the last layer of dirt from the skeletons, they donned full-body biohazard gear – and this was merely the first step through a gauntlet of sterility that might have been invented by a demented Mr. Clean. Afterwards they compared the recovered DNA to a database of present-day DNA

types, just to make sure it didn't come from anyone born this side of the Dark Ages – and it didn't.

Finally, to quantify what sort of contamination is produced by standard operating procedures, they had eight samples taken according to current (less stringent) handling practices. Four of these picked up stray DNA, underscoring the importance of cleanliness in studying ancient genetic material.

Beyond keeping clean, what else did they learn? In population genetics terms, not much. A few of the samples' genetic signatures don't show up in modern Scandinavians, which is mildly interesting but not terribly surprising. A few others show up throughout western and central Europe – hardly surprising, given the Vikings' longboat-borne migrations.

There is, however, a seriously cool entertainment possibility in the research: just take this story, add the ability to revive ancient DNA, toss in some embryonic genetic modification and – voila! – a ready-made Hollywood schlockbuster plot. I can just see the pitch session now: "It's like Boys From Brazil, but with Harald

Hardrade."

Not that I'm advocating this in reality, nor are the scientists, nor is it scientifically possible. Or is it? Recall some famous advice, coincidentally also set in Denmark: There are more things in heaven and Earth, Horatio, then are dreamt of in your PubMed abstracts....

Evidence of Authentic DNA from Danish Viking Age Skeletons Untouched by Humans for 1,000 Years [PLoS ONE]

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Image: PLoS ONE*

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