Say what you like about all the fighting and pillaging and invading and stuff, Vikings were really good when it came to eating a healthy diet.
Being a seafaring and coastal people, it isn’t surprising that the great warrior hordes from the north ate a lot of fish – but that fact has proven to be troublesome for modern day archaeologists trying to tease out the history of Britain in the first millennium CE.
Indeed, accounting for a cuisine high in seafood has now enabled a team of researchers to finally resolve a particularly puzzling question regarding a mass grave unearthed in the English county of Derbyshire.
The grave was discovered by archaeologists Martin Biddle and Birthe Kjølbye-Biddle, in the grounds of St Wystan’s Church in the town Repton.
Conducting a series of excavations in 1970s and 80s, the pair found a collection of bones belonging to 264 people buried beneath a mound above the remains of a partially demolished chamber of what is thought to have been an Anglo-Saxon royal mausoleum.
In among the remains, Biddle and Kjølbye-Biddle found a number of trademark Viking artefacts, including axes, knives and silver pennies. The currency dated to a very narrow period – 872 to 875 CE.
Evidence from previous research showed that the Great Viking Army wintered at Repton in 873 CE, having driven out the resident Mercian king.
Reconstructing the skeletons, the researchers found that 80% belonged to men and the rest to women. Most were aged between 18 and 45 and a great many bore marks of severe injury. The assumption, then, that the grave contained the remains of Viking war dead was perfectly rational.
Follow-up carbon dating, however, confounded the idea. Dating results returned a wide range of indicative ages, suggesting that the bones had been deposited at the site over several centuries.
The archaeological evidence, therefore, was incompatible with the dating evidence, leaving an apparently insoluble mystery.
Now a team led by Cat Jarman from the University of Bristol’s Department of Anthropology and Archaeology seems to have resolved the issue once and for all. And the key, it turns out, was fish.
In a paper published in the journal Antiquity, Jarman and her colleagues report a new round of carbon dating. The results indicate that all the bones were deposited in the mass grave during a “single event” that took place between 779 and 887 CE.
This range can be considerably narrowed once dating on single and double graves unearthed nearby are taken into account. These yielded a possible range of 872 to 885 CE.
Jarman’s team suggest the true age of the mass grave is thus likely to be 873 CE – consistent with historical records.
The centuries-wide range of the first attempt at dating the bones, Jarman explains, arose because the original researchers failed to take into account a phenomenon known as the marine reservoir effect.
“When we eat fish or other marine foods, we incorporate carbon into our bones that is much older than in terrestrial foods,” Jarman explains.
“This confuses radiocarbon dates from archaeological bone material, and we need to correct for it by estimating how much seafood each individual ate.”
Over decades, numerous researchers have analysed skeletons and settlements, using several methods, including stable isotope analysis, to determine the make-up of the Viking diets. And while, naturally, this changed according geological location, fish was generally a big component.
Indeed, one study of Viking settlement in northern Scotland found that Vikings settling on the islands of Orkney and Shetland boosted the amount of fish they ate by increasing the amount of time they spent deep-sea fishing.
Although pleased with the new results, Jarman is quick to point out that the dating, however accurate, and the artefacts, however unquestionably Viking in origin, do not prove beyond all doubt that Repton’s corpses are war dead.
That said, she’d be ready to take a bet on it.
“The date of the Repton charnel bones is important because we know very little about the first Viking raiders that went on to become part of considerable Scandinavian settlement of England,” she says.
“Although these new radiocarbon dates don’t prove that these were Viking army members it now seems very likely. It also shows how new techniques can be used to reassess and finally solve centuries old mysteries.”