Ancient mtDNA from 22 individuals from two sites in Southern Denmark have been isolated, sequenced and analyzed. The two sites are Bøgebjerggård and Skovgaarde. On the map to your right, they are marked as B for Bøgebjerggård and S for Skovgaarde. They date to the Danish Roman Iron-Age period, or approximately 2000 to 1600 years ago. Bøgebjerggård yielded the remains 15 individuals, but only 8 were analyzed in this paper: 4 males, 3 females, and 1 individual whose sex could not be determined. Skovgaarde yielded the remains of 19 individuals, but only 14 were analyzed for this paper: 1 male, 9 females, and 4 individuals whose sex could not be determined.
The report of the ancient mtDNA analysis has been published in the American Journal of Physical Anthropology. In the paper, “Rare mtDNA Haplogroups and Genetic Differences in Rich and Poor Danish Iron-Age Villages,” I did not read about any discussion of a sterile excavation. It seems as if the remains were removed and curated at the Institute of Forensic Medicine, in the University of Copenhagen for several decades. Owen Lovejoy and other notable phyiscal anthropologists have analyzed the remains to determine sex and the age at death.
The fact that a sterile excavation was not done and at least a half dozen analysts touched the remains, presumably with non-sterile technique, is troublesome for any accurate ancient DNA analysis. One way the authors of this paper compensated was to sample mtDNA from within teeth that were still sitting snug in the alveolus.
DNA isolation and amplification was done in a clean laboratory with the highest grade reagents. The authors mention all the precautions they took to avoid contamination. I would not expect anything otherwise! The products of the PCR were further amplified using Topo TA cloning. I do not know why.
Approximately, 340 bases of the Hyper Variable Region 1 (HVR-1) of the mitochondrial genome was amplified of from 22 individuals. In some cases isolations from three teeth were used per individual, but I can’t tell if they were combined because there was not enough DNA or if they were keep seperately as part of a validation control layer.
Once the sequences were acquired, the authors performed a haplogroup comparison of the samples to a ‘private’ mtDNA database they maintain. There was not a discussion about how robust their private database is and that is very concerning. If their database was relatively small, i.e. not many samples, that would seriously hinder their ability to resolve fine differences. What is just as curious is that there was no discussion about why the authors decided to use their own database! There are large, accurate datasets out there that many people use. The authors could have also compared their sequences to these public datasets to validate their results!
Either way, the big headline find from this sequence comparison is that one individual, a male, from Bøgebjerggård carried the haplogroup R0a in his mitochondrial genome. This haplogroup is rarely found in modern Danish populations and not found in any of the other ancient Danish remains. This haplogroup is, however, found in sporadically in South Eastern Europe populations but predominately found in populations of Arab ancestry — Bedouins in the Arabian Peninsula, Yemenites and Ethiopian Jews, and Somalis.
Ask yourself is this surprising? No it is not. In April we read of archaeological evidence of Middle Eastern coins from the 7th century in Sweden. This indicates people were actively migrating back and forth between the Near East and Northern Europe, exchanging goods and probably exchanging genes.
Does this finding warrant headlines like, “Adolf Hitler’s Aryan theory rubbished by science” appearing in the newspaper the Telegraph? No, it does not. Like I said, this finding isn’t surprising nor does it mean that 1 individual in Iron-Age Denmark throws off the whole genetic composition of an entire population. The overwhelming majority of Danes do not carry this haplogroup. So, the presence of the remains of male with with the haplogroup R in his mtDNA simply suggests he is of Near Eastern descent.
- Melchior, L., Gilbert, M., Kivisild, T., Lynnerup, N., Dissing, J. (2008). Rare mtDNA haplogroups and genetic differences in rich and poor Danish Iron-Age villages. American Journal of Physical Anthropology, 135(2), 206-215. DOI: 10.1002/ajpa.20721