TY - JOUR
T1 - Problems associated with the AMS dating of small bone samples
T2 - The question of the arrival of Polynesian rats to New Zealand
AU - Higham, T. F.G.
AU - Hedges, R. E.M.
AU - Anderson, A. J.
AU - Ramsey, C. Bronk
AU - Fankhauser, B.
PY - 2004
Y1 - 2004
N2 - 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).
AB - 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).
UR - http://www.scopus.com/inward/record.url?scp=3543140159&partnerID=8YFLogxK
U2 - 10.1017/S0033822200039539
DO - 10.1017/S0033822200039539
M3 - Article
SN - 0033-8222
VL - 46
SP - 207
EP - 218
JO - Radiocarbon
JF - Radiocarbon
IS - 1
ER -