It is still unusual when the Catholic church allows a scientific study of one of their relics. So I was surprised to find the manuscript describing the study of the DNA of the remains of one of Europe's patron saints, St. Birgitta (Bridget of Sweden) in my PLoS One inbox one fine day in May, 2008. I'm a neurogeneticist by training, so I felt competent to take this manuscript on as academic editor. The manuscript stated that they had found through both DNA analysis and carbon dating that not only were the remains of St. Birgitta most likely not from the relevant time period, but that the remains stored with her, once thought to be her daughter, could not possibly have been from any of her relatives, let alone her daughter.

Such claims, sure to stir some public attention, needed a thorough peer-review process. I selected a team of four high-caliber international experts in both the field of ancient DNA analysis and radiometric dating. I also used a scheduled visit to Uppsala, where the work had been done, to meet the last and corresponding author of the manuscript, Marie Allen, and have a good look at the laboratories where the experiments had been made. Marie was the most gracious host and took a lot of time out of her busy schedule to show me around her lab and explain how professionally she had handled the relics according to the latest techniques.

The review-process was a lot more bumpy and time-consuming. The reviewers all liked the way she had handled and analyzed the DNA and only had minor suggestions for improvement in this respect. The radiocarbon dating itself was also ok, but two of the reviewers brought up the "reservoir effect". This could lead to a deviation in radiocarbon dating from the correct age if the two people had been on a high-seafood diet. To measure this reservoir effect, additional Nitrogen-dating techniques had to be applied. These proved difficult and time consuming, but after more than one year, the results were finally coming in. Indeed, there had been a measurable reservoir effect for both tested skulls, albeit not to a degree that would change the main conclusions of the study. Yesterday, almost 2 years after the initial manuscript had been submitted, the paper was finally published and I think both DNA and dating measurements are as accurate as they can possibly be, given today's technology. These measurements show that it is highly unlikely that the two skulls kept as relics by the Catholic church are the ones from St. Birgitta and her daughter. Most likely, not even one of the skulls comes from the person claimed by the church.

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Nilsson, M., Possnert, G., Edlund, H., Budowle, B., Kjellström, A., & Allen, M. (2010). Analysis of the Putative Remains of a European Patron Saint–St. Birgitta PLoS ONE, 5 (2) DOI: 10.1371/journal.pone.0008986