Ten previously unexcavated graves were chosen to test if applying modern forensic method to thousand-year old remains would provide genetic researchers with guaranteed uncontaminated DNA. Having ascertained that the samples were indeed uncontaminated, their analysis corroberated hypotheses formed from other information gathered by archaeologists and anthropologists.
The research team have previously obtained mitochondrial DNA sequence results on subjects from:
- an early Christian cemetery (AD 1000–1250)
- two Roman Iron Age settlements (AD 0–400)
- Greenland Inuit (AD 1450)
Altogether, the comparative data used comes from a database of 15,854 examples available to the team.
When the complexity of the genetic origins of the individuals suggested by the range of markers is considered, the high value of the forensic precautionary measures and provision of exclusive laboratory conditions in this case is justified. Confidence may be placed in the authenticity of the data where accidental contribution of modern DNA during the archaeological recovery process is eliminated.
mtDNA Haplogroups and Genetic Origins of Vikings
A possible European, perhaps Viking, origin of the X2a haplotype identified among Native Americans has been suggested but has not been detected in Europe and the present observation of X2c amongst the Vikings does not support this.
Among present day Scandinavians a marker known as Hg I constitutes less than 2%, but researchers have previously observed a frequency of 10–20% of it in Danish Iron Age and Viking Age population samples. With the observation of Hg I for one subject of the ten tested, this trend (10%) is therefore assumed for the Viking sample from Galgedil. This marker enjoys a low frequency among other ancient populations in:
- Italy
- Spain
- Great Britain
- early central European farmers
Loosely translated, this means that a phylogenetic line (genetic tree branch) drawn from contemporary European populations connects to each of the ten individuals, yet half do not connect in the same way with modern Scandinavians. They do connect through previous findings of a pronounced frequency of this haplogroup in Viking and Iron Age Danes.
Therefore, the Viking population sample from Galgedil does not differ significantly from other Viking and Iron Age population samples from the Danish past.
Forensic Method Highly Effective
The proven presence of ten different haplotypes from ten individuals is taken as evidence that the forensic precautions actually worked, because contaminated samples would have demonstrated commonalities with modern DNA (and positive matches with samples from individuals handling the samples).
Forensic caution to prevent cross-contamination of ancient tissue collected archaeologically is continued in other genetic analyses, noteably the attention given to cleaning hair samples analysed for mtDNA and full genome sequencing for an Ancient Human originating from Greenland permafrost at Saqqaq.
The retrieval of uncontaminated DNA from the remains of ancient humans is important because it provides opportunity for further understanding of migration patterns, tribal and family structure, as well as the hope of discovering the origin of certain genetic diseases.
Source
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
The authors thanked Camilla Friis, Marianne Olesen and Margrét Kristiansdottir for skilful technical assistance, Hans Sigismund for performing the permutation analyses, Pia Bennike and Kirsten Prangsgaard for information regarding the ten subjects, the history of Galgedil and assistance with obtaining DNA samples from all the archaeologists involved in the exhumation.
Valerie Williamson - Dr. Val Williamson is a freelance journalist and academic specialising in historical and popular culture topics.
