12 research outputs found
14C dateringer af menneskeknogler: Med de gr酶nlandske nordboer som eksempel
14C Dating of human bones. Using the Greenland Norse as an example By Jette Arneborg, Jan Heinemeier, Niels Lynnerup, Niels Rud and 脕rny E. Sveinbj枚rnsd贸ttir
The article gives an overview of the difficulties encountered in interpreting 14C dating of human bone, which may lead to erroneous results. Human food intake often has a considerable marine component, which leads to an increase in the apparent 14C age of human bones due to the so-called marine reservoir effect, i.e. the apparent 14C age difference between contemporaneous marine and terrestrial organisms. The marine reservoir age typically amounts to about 400 14C years, which is therefore the expected 14C age excess in humans with 100% marine food intake. Measured values of the carbon stable-isotope ratio 13C/12C in bone collagen, expressed in terms of its fractional deviation from a standard, 未13C, may be used to assess the fraction of marine food in a mixed diet. Typical sources of error, which, particularly in the past, have lead to misinterpretation of 14C dates of bones of humans or animals with mixed marine/terrestrial diet, are 1) Under-estimation of the required 14C reservoir correction based on measured 未13C values 2) The marine food component originates partly from fjord or estuarine environments, for which reservoir ages of more than 900 years have been found in some parts of Denmark 3) Intake of freshwater fish from lakes and rivers, which, in areas of Denmark with calcareous underground, may have very high reservoir effects that unfortunately will not be revealed by 未13C measurements. We use our 14C and 未13C investigation of about 30 Greenland Norse bone and textile samples as an example of how human bone may be successfully 14C dated under favourable conditions where the difficulties 2) and 3) do not apply. With the use of reservoir corrections based on a calculated marine food component varying from 20 to 80%, the corrected 14C ages ranged from about AD 980 to 1430, i.e. most of the time span of the Norse colonisation of Greenland. We used comparative dating of textiles (terrestrial origin) and skeletons with a high marine content (80%), which had been wrapped in the textiles for burial, to calibrate the reservoir correction. Finally we point to the possibility of using the nitrogen isotope 15N in bone collagen as an indicator of a dietary component of freshwater fish
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Change of Diet of the Greenland Vikings Determined from Stable Carbon Isotope Analysis and 14C Dating of Their Bones
Bone samples from the Greenland Viking colony provide us with a unique opportunity to test and use 14C dating of remains of humans who depended upon food of mixed marine and terrestrial origin. We investigated the skeletons of 27 Greenland Norse people excavated from churchyard burials from the late 10th to the middle 15th century. The stable carbon isotopic composition (delta-13C) of the bone collagen reveals that the diet of the Greenland Norse changed dramatically from predominantly terrestrial food at the time of Eric the Red around AD 1000 to predominantly marine food toward the end of the settlement period around AD 1450. We find that it is possible to 14C-date these bones of mixed marine and terrestrial origin precisely when proper correction for the marine reservoir effect (the 14C age difference between terrestrial and marine organisms) is taken into account. From the dietary information obtained via the delta-13C values of the bones we have calculated individual reservoir age corrections for the measured 14C ages of each skeleton. The reservoir age corrections were calibrated by comparing the 14C dates of 3 highly marine skeletons with the 14C dates of their terrestrial grave clothes. The calibrated ages of all 27 skeletons from different parts of the Norse settlement obtained by this method are found to be consistent with available historical and archaeological chronology. The evidence for a change in subsistence from terrestrial to marine food is an important clue to the old puzzle of the disappearance of the Greenland Norse, obtained here for the first time by measurements on the remains of the people themselves instead of by more indirect methods like kitchen-midden analysis.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202