Stable Isotopes and the Medieval Cod Trade

Have you noticed what an enormous role stable isotopes are taking in archaeological research these days?

Cod Drying on a Rack Near Lofoten, Norway
Photo Credit: Andrea Raviglione

The reason that stable isotopes are so useful, not to go into any great detail, is that they are geographic markers for anything organic. See, heavy and light metals are found in varying concentrations all over the planet. People and plants and animals all absorb those chemical combinations in one way or another all their lives, and they store that information in different places---their bones and muscles and teeth and, uh, plant wall cells. So, for example, somebody raised in one part of the world who spends their adult life in another part of the world has both the isotope signature of their birth stored in them, and the isotope signature of their adulthood. (For more detail see the Stable Isotope for Dummies article.) The whole process of discovery is actually quite interesting, if a bit technical, and the applications are myriad these days.

One application just got published in the Journal of Archaeological Science this month: determining the provenance of medieval codfish bones. There are medieval documents that mention codfish as a commercial product of Arctic Norway by the 12th century; but those aren't particularly detailed documents. We don't really know how and when codfish trade got started, or how widespread the practice was.

But, discovering an Arctic Norway codfish bone in a 9th-11th century Viking site in what is now Poland is pretty darn interesting, wouldn't you say? Me, too.

Sources and Further Info

Barrett, James, et al. 2008 Detecting the medieval cod trade: a new method and first results. Journal of Archaeological Science 35(4):850-861.

Stable Isotope for Dummies, somewhat more detailed explanation of the concept.

Recent applications of stable isotope research