A Curious Statistical Anomaly

I know this is a bit old for news but I finally found the original research article and got a chance to read it and then follow up with some encyclopedia entries on haplotypes and haplogroups.

Basically, getting DNA from archaeological sites isn’t that difficult. What is difficult is getting a sample that hasn’t been contaminated by modern DNA. Think of all the people that work on archaeological sites, and that just the tip of the iceberg for counting the people that may have handled the material or touched something that was on them when they handled the material (food, drink, the last person they shook hands with, and on and on). This group was trying to see if they left a layer of dirt over the object (skull in this case) and then that last layer would be removed by scientists in clean suits (shown in the image) and placed in a sterile environment for transport to their clean lab for extraction and further testing.

This is what they found:

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.

Personally, I find this work fascinating. Imagine being able to gather information about our ancestors and telling who they may have met, fell in love (that’s guess work of course — I’m being romantic here), married and had children with. Of course, in the case of Vikings, with their reputation as fighters and pillagers it’s was probably wasn’t as nice and light as I make it out to be.

But the fact is, these scientist did managed to get clean samples and learn from the DNA samples that they got. This sample size of ten adult Viking villagers (3 males, four females for sure and two males and 1 female possibly) is too small a size to determine absolutes but it is a start.

Also, I very much appreciate that these scientists (Linea Melchior, Toomas Kivisild, Niels Lynnerup, Jørgen Dissing) released their research paper under Creative Commons licensing. I’m a science news junkie but I really, really, really, appreciate being able to return to the source of the article whenever I can. Things are much more likely to be misunderstood when the original article isn’t available. Even so any problems with interpretation of these results are mine alone. Check out the paper and think of the possibilities. Yeah, science!