STABLE ISOTOPIC INSIGHTS INTO THE SUBSISTENCE PATTERNS OF PREHISTORIC DOGS (CANIS FAMILIARIS) AND THEIR HUMAN COUNTERPARTS IN NORTHEASTERN NORTH AMERICA

Abstract

There are four goals to this study. The first is to investigate the diet of prehistoric dogs (Canis familiaris) in the Northeast region of North America using stable isotope analysis. The second goal of this study is to generate independent data concerning the presence or absence of C4 resources, such as maize, in the diets of dogs. Third, this study investigates the use of dog bone as a proxy for human bone in studies assessing the presence of C4 resources at archaeological sites. The fourth goal of this study is to provide a check on existing interpretations of the material, macro- and micro-botanical records as it concerns the presence or absence of C4 resources at the sites involved in this study. Stable isotope analysis is a science that allows the measuring of the abundance ratio of two stable isotopes of a particular element. Stable isotope analysis can differentiate C4 and C3 plants, as well as terrestrial and marine resources in material such as bone where the chemistry of diet becomes recorded. Given the importance of C4 plants to many prehistoric populations, in the absence of direct evidence identifying their presence at archaeological sites, an alternate method for identification is needed. Maize played an important role in changing human behaviors during prehistory including: decisions to increase sedentism, abuse of power structures, and stratification of gender roles within human populations. Additionally, an overall decrease in health is seen in prehistoric populations who focused their subsistence practices on maize. Dogs were chosen as the focus of this study because related research suggests that their diet tends to mimic human diet. Prehistoric dogs were scavengers, but they were also intentionally fed companions. The suggestion that dog diet in some way mimics human diet means that stable isotope ratios from their bone will reflect the type of resources available for consumption by their human counterparts. As such, this investigation may also indirectly inform on the diets of the American Indian inhabitants of the settlements in which these dog remains originate. Thirty samples of dog bone, dating from the Early Ceramic Period, ca. 3000 B.P. to the Late Woodland and Early Historic Period, were obtained from museum and personal collections, and from ongoing archaeological excavations throughout the Northeast region of North America. Stable isotope analysis was conducted at Notre Dame's Center for Environmental Science and Technology. The results of this analysis indicates that these prehistoric dogs consumed the types of resources represented in the archaeological record with one important exception: consumption of C4 resources, possibly maize, was occurring at several sites where no other evidence of C4 exploitation exists. Of the dogs sampled ten were from pre-agricultural sites in Maine and their stable isotope ratios indicated a diet of marine and terrestrial resources. Nineteen dogs were excavated from components dating to the Late Woodland or Historic Period. During the Late Woodland and Historic Period the C4 plant maize was exploited by many human groups in the study region. Interpretation based on stable isotopes from bone collagen indicates that six of these dogs had isotopic signatures within the range of significant C4 resource consumption. Stable isotope ratios from the remaining dogs indicate a smaller contribution of C4 resources to diet. According to 13C ratios from carbonate three dogs, two from New Jersey (DB2, DB8) and one from Maryland (DB11), had a significant C4 plant component to their diet. The remaining Late Woodland and Historic period dogs most likely consumed minor amounts of C4 resources. In addition to identifying C4 resources in the diet of dogs, the value of assessing isotope data from both collagen and carbonate is investigated. The sample size for this study was small in comparison to the size of the region assessed. Despite the small sample size, this analysis contributes to our knowledge of past dog and human subsistence patterns. Our understanding of the utility of stable isotope studies of human companion species has also expanded. In addition to investigating the presence of C4 resources in the diet of prehistoric dogs, this research provides an alternate line of inquiry to re-assess current interpretations, especially in areas where direct evidence of isotopically identifiable C4 plants, such as maize are currently lacking. The results of this study are applicable first and foremost to the consumption patterns of the individual animals sampled. However, that these dogs were consuming particular resources provides at least a clue of what was under consideration by their human counterparts.