Evidence of Authentic DNA from Danish Viking Age Skeletons

[Breogan]

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

Linea Melchior1, Toomas Kivisild2, Niels Lynnerup3, Jørgen Dissing1*
1 Research Laboratory, Institute of Forensic Medicine, University of Copenhagen, Copenhagen, Denmark2 Leverhulme Center for Human Evolutionary Studies, The Henry Wellcome Building, University of Cambridge, Cambridge, United Kingdom3 Laboratory of Biological Anthropology, Institute of Forensic Medicine, University of Copenhagen, Copenhagen, Denmark


Abstract

Background
Given the relative abundance of modern human DNA and the inherent impossibility for incontestable proof of authenticity, results obtained on ancient human DNA have often been questioned. The widely accepted rules regarding ancient DNA work mainly affect laboratory procedures, however, pre-laboratory contamination occurring during excavation and archaeological-/anthropological handling of human remains as well as rapid degradation of authentic DNA after excavation are major obstacles.

Methodology/Principal Findings
We avoided some of these obstacles by analyzing DNA from ten Viking Age subjects that at the time of sampling were untouched by humans for 1,000 years. We removed teeth from the subjects prior to handling by archaeologists and anthropologists using protective equipment. An additional tooth was removed after standard archaeological and anthropological handling. All pre-PCR work was carried out in a “clean- laboratory” dedicated solely to ancient DNA work. Mitochondrial DNA was extracted and overlapping fragments spanning the HVR-1 region as well as diagnostic sites in the coding region were PCR amplified, cloned and sequenced. Consistent results were obtained with the “unhandled” teeth and there was no indication of contamination, while the latter was the case with half of the “handled” teeth. The results allowed the unequivocal assignment of a specific haplotype to each of the subjects, all haplotypes being compatible in their character states with a phylogenetic tree drawn from present day European populations. Several of the haplotypes are either infrequent or have not been observed in modern Scandinavians. The observation of haplogroup I in the present study (<2% in modern Scandinavians) supports our previous findings of a pronounced frequency of this haplogroup in Viking and Iron Age Danes.

Conclusion
The present work provides further evidence that retrieval of ancient human DNA is a possible task provided adequate precautions are taken and well-considered sampling is applied.

Citation: Melchior L, Kivisild T, Lynnerup N, Dissing J (2008) Evidence of Authentic DNA from Danish Viking Age Skeletons Untouched by Humans for 1,000 Years. PLoS ONE 3(5): e2214. doi:10.1371/journal.pone.0002214
Editor: Niyaz Ahmed, Centre for DNA Fingerprinting and Diagnostics, India
Received: February 7, 2008; Accepted: April 2, 2008; Published: May 28, 2008
Copyright: © 2008 Melchior et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported by external funding from the VELUX FOUNDATION. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: joergen.dissing@forensic.ku.dk


more on PLoS ONE: Evidence of Authentic DNA from Danish Viking Age Skeletons Untouched by Humans for 1,000 Years

[Menydh]

This is interesting

Rare mtDNA haplogroups

Given the small sample sizes the Viking population sample from Galgedil does not differ significantly from other Viking and Iron Age population samples from the Danish past by the haplogroup frequency distribution, however, it is noted that five of the ten subjects harbour mtDNA haplotypes which have either not been observed or are infrequent in modern Scandinavians (Table 1). In particular the observation of haplotype X2c is interesting (subject G7). Haplogroup X is itself rare (0.9% in Scandinavians [51]) but has a very wide geographic range, and X2c is a rare subgroup of X accounting for only 5% of 175 Hg X samples surveyed in 2003 [52]. A possible European (Viking?) origin of haplotype X2a identified among Native Americans has been suggested [53], [54], but X2a has not been detected in Europe and the present observation of X2c amongst the Vikings does not support this proposal.


Among present day Scandinavians Hg I constitutes <2% [55], [56], however, we have previously observed a markedly higher frequency (10–20%) of Hg I in Danish Iron Age and Viking Age population samples (Table S3) [16], [21]. With the observation of Hg I for subject G6 this trend is also seen for the Viking population sample from Galgedil. Interestingly, Hg I shows a low frequency (1 out of 114 subjects) among other ancient populations in Italy, Spain, Great Britain, and early central European farmers [11], [12], [43], [57].