28 May 2008

Viking DNA Retrieved

by Kate Melville

As well as raping and pillaging, Vikings are usually remembered for their horned helmets, but in a new study published in the journal PLoS ONE researchers have now begun investigating what went on under the helmet. To help understand these fearsome Norsemen, J�rgen Dissing and colleagues from the University of Copenhagen have managed to extract what they believe is authentic DNA from ancient Viking skeletons, and importantly, have avoided many of the problems of contamination faced by past researchers.

DNA analysis from the remains of ancient humans can provide valuable insights into such important questions as the origin of genetic diseases, migration patterns and tribal movements. But problems connected with the retrieval and analysis of DNA from ancient organisms (like the scarcity of intact molecules) are further aggravated in the case of ancient humans. This is because of the great risk of contamination with DNA from modern humans. Because humans are involved at all steps, from excavation to laboratory analyses, past DNA extractions have been dogged by contamination controversies. Some researchers even claim that it is impossible to obtain reliable results with ancient human DNA.

But Dissing believes that his samples, from a one-thousand year old burial site on the Danish island of Funen, are indeed authentic DNA from ancient humans. Wearing protective suits, the researchers removed the teeth from the jaw at the moment the skeletons were unearthed when they had been untouched for 1,000 years. The subsequent laboratory procedures were also carefully controlled in order to avoid contamination.

Analysis of the Viking DNA showed no evidence of contamination with extraneous DNA, and typing of the endogenous DNA gave reproducible results and showed that these individuals were just as diverse as contemporary humans. Dissing's work is important, as a truly reliable retrieval of DNA opens the way for a valuable use of prehistoric human remains to illuminate the genetic history of past and extant populations.

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Source: Public Library of Science