Problems associated with the AMS dating of small bone samples: the question of the arrival of Polynesian rats to New Zealand
Date
2004
Authors
Higham, Thomas F. G.
Hedges, Robert E M
Anderson, Atholl
Ramsey, Christopher Bronk
Fankhauser, Barry L
Journal Title
Journal ISSN
Volume Title
Publisher
University of Arizona
Abstract
We have AMS dated samples of Pacific rat (Rattus exulans) bone "collagen" and filtered gelatin samples from the prehistoric site of Shag River Mouth, New Zealand. The age of occupation of this site has previously been determined based on 50 radiocarbon measurements. The site dates to the late Archaic phase of southern New Zealand prehistory (about 650-500 BP; 14th-15th century AD). The results of rat bones which we have dated produce a range in ages, from about 980-480 BP, a difference we attribute to a combination of effects. Pretreatment appears to be an important variable, with results showing differences in 14C age between the progressive "collagen" and filtered gelatin chemical treatment stages. Amino acid profiles suggest there is a proteinaceous but non-collagenous contaminant which is removed by the more rigorous pretreatment. Stable isotopes vary between pretreatments, supporting the removal of a contaminant, or contaminants. Variation in δ15N values imply a range in uptake of dietary protein, and might suggest a potential influence from the local aquatic environment or the consumption of marine-derived protein. Rats are opportunistic, omnivorous mammals, and, therefore, obtain carbon from a variety of reservoirs and so we ought to expect that in environments where there is a variety of reservoirs, these will be exploited. Taken together, the results show that rat bone AMS 14C determinations vary in comparison with the established age of the site, but are in notably better agreement with non-collagenous data than in previously published determinations (Anderson 1996).
Description
Keywords
Keywords: amino acid; carbon 14; collagen; gelatin; nitrogen 15; protein; stable isotope; accelerator mass spectrometry; accuracy assessment; bone; migration; radiocarbon dating; rodent; accelerator mass spectrometry; age determination; animal tissue; aquatic envir
Citation
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Source
Radiocarbon
Type
Journal article