An initial study of the ¹³ C values for human bone collagen of 27 Norse Greenlanders in the late 1990s suggested a change in the Norse diet from predominantly terrestrial to predominantly marine food. This shift may well indicate a change in diet; the question left open by the limited initial isotope study was, however, whether the change in diet was a reflection of altered subsistence strategies or altered farming practices. Furthermore, the first study did not convincingly answer the question of whether the dietary change occurred gradually over time or within the space of a few years—and, if the latter case, when? Neither did it answer questions concerning dietary differences between the two Norse settlements, between individual farms and between the sexes, or the nature of the marine food that was consumed. Distinguishing locally born people from foreigners is yet another matter for investigation in order to leave out of account persons that grew up outside of Greenland. This new study includes 437 samples: 183 from humans—118 Norse and 65 Inuit—and 254 from animals. The samples are from 19 Norse sites (farms): 13 from the Eastern Settlement and 6 are from the Western Settlement. For comparison, we have also included samples from both humans and animals from 22 Inuit sites. This paper sets the scene for the new study and the following papers in this Special Volume. Former studies in Norse diet and Norse resource utilization are recapitulated, and all the Norse sites represented in the study are presented, as are all the samples included in the study. Chronology is a recurrent problem in Norse archaeology, and our focus, in particular, is on the attempt to date the samples included in the study that have not been radiocarbon dated.

Isotopic measurements of the terrestrial and marine wild animal species of greatest importance to Greenlandic Norse and Neo-Eskimo people were obtained to provide a solid basis for undertaking isotopic dietary analyses of these two human groups. The samples studied were animal bones from archaeological excavations of Norse and Neo-Eskimo middens. As expected, the values for the terrestrial and marine species were found to have characteristic isotopic composition, but there is sufficient variation within each group to require detailed consideration in interpreting isotopic information on the humans.

The isotopic dietary method has been applied to samples of some 65 Thule Culture individuals from existing archaeological collections of Greenlandic human skeletal material. The aim was to use the Greenlandic Thule Culture as a test of the isotopic method, in that we know they were heavily dependent on marine resources, and should thus provide a direct measure of the isotopic values for humans consuming almost entirely marine protein. The sites from which the material was originally obtained encompass almost the entire periphery of Greenland. Isotopic data from a study of animals of Greenland was used as the basis for analysis. As expected, the results indicate that these people were almost entirely dependent on the marine biosphere for their protein. An exception is those from Northeast Greenland, whose isotopic signatures show evidence for consumption of terrestrial protein as well. Not expected were the observed differences at the regional and local levels.

An archaeological commentary is given on the results of the first isotopic study of the Greenland Thule culture. To test the isotopic data derived from human remains from the graves, comparative archaeological data of the faunal and artifactual material from the sites are presented. To make the two data sets comparable, the faunal material are presented in NISP and the artifactual material are presented as technounits. The three data sets given, i.e., the isotopic, the faunal, and the artifactual, confirm that the Inuit were heavily reliant on marine protein and resources. Exceptions are those from Northeast Greenland, whose isotopic signatures show evidence of consumption of terrestrial protein as well, a statement confirmed by the archaeological material, faunal as well as artifactual, showing that ca. 20% and 40% of bones as well as technounits found on coastal and inland sites, respectively, are related to terrestrial resources. The conclusion made is that the isotopic analyses are valid in archaeological contexts and support the archaeological material. Concerning the substantial use of inland resources in Northeast Greenland compared with the ethnographically documented intensive caribou hunting in West Greenland, the former region still remains most enigmatic from a cultural point of view.

To provide a basis for the isotopic dietary study of the Greenland Norse, and as an interesting study in itself, measures of the stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios were obtained for 118 samples of archaeological bone from 6 species of the Norse domestic animals. These samples were obtained from museum faunal collections representing archaeological excavations of 10 Norse sites, five in each of the two Norse settlements in Greenland. In general, the carbon isotope values for the herbivores of dietary importance (cattle, sheep, and goats) were as expected for animals living in a C₃ environment. The nitrogen isotope data hint at differing field management practices between the two settlements. There is no isotopic evidence for any unusual pastoral adaptation to conditions in Greenland, or for any change in animal management over the lifetime of the settlements. A few pigs form an exception to this statement, but they are peripheral to the Norse dietary economy. These data provide a solid first data set on which to base isotopic dietary analyses of the Norse settlers themselves.

Our understanding of the Norse dietary adaptations to their Greenlandic home comes primarily from sparse historical records, from what is known of the Norse dietary economy in other North Atlantic lands, and from zooarchaeological examinations of the animal bones found in the various excavations of Norse Greenlandic sites which have taken place over the past century. To obtain more detailed information on the diets of the Norse settlers in Greenland, measures of the stable carbon (δ¹³C) and nitrogen (δ¹⁵N) values of human bone collagen have been made for 80 individuals from an existing collection of Norse skeletal material. The material is from five churchyards in the Norse Eastern Settlement and two churchyards in the Western Settlement. These data are interpreted with the aid of similar data obtained for the wild fauna of Greenland, for the Norse domestic animals and for a number of Thule Culture individuals of about the same time period. It is clear that application of the isotopic dietary method to Greenland is complex, but even so, it can provide very useful information. It is also clear that the isotopic method provides reliable information on Greenlandic diet even at the level of the individual. For the two Norse settlements taken as a whole, the basic dietary economy was based about as much on hunting as it was on their domestic animals. We see no evidence for real differences between the diets of men and women or between individuals of different ages. The large individual differences are then likely connected to status or circumstance, but not to sex or age.

In this concluding paper of the JONA special volume on the Norse Greenland isotope study, we summarize the archaeological interpretations of the previous, technical papers. The study supports the conclusions and widens the results of our earlier limited study, i.e., that the diet of the Norse Greenlanders became more dependent on marine resources over time. The isotope data provide information at the level of the individual, and the study indicates that the Norse Greenlanders had an isotopically varied diet; there is no evidence that these differences were linked to sex or age. The shift in diet seems to have happened gradually, perhaps beginning during the initial settlement. The swiftness of the change, however, depended on where the immigrants settled; settlers in the southern part of the Eastern Settlement and in the Western Settlement may have adapted to the marine resources more rapidly than those in the central Eastern Settlement region. Social differences may partly explain the isotopically varied diet within Norse society; this explanation is, however, not without its reservations. Despite the changes in the dietary economy, and the increasing dependence on the marine resources, farming strategies remained unchanged. Climate change and unsustainable land-use practices have been proposed as two of the main reasons for the depopulation of the Norse Greenland settlements in the late 1400s, and it is obvious to draw attention to these factors when trying to explain the changes in the dietary economy. It is, however, more doubtful whether the environmental changes were, after all, the sole cause of the depopulation of the Norse Greenland settlement. The Norse Greenlanders apparently adapted well to their physical environment, and they could survive on the marine resources in as far as they were available.

The protocol for collagen extract used in the Greenland Isotope Project as discussed in the papers comprising the Journal of North Atlantic Special Volume 3, Greenland Isotope Project: Diet in Norse Greenland AD 1000–AD 1450, is described here in detail.