Amino acid radiocarbon dating

Amino acid racemization dates on bone have been reported for 36 sites throughout the world (14-18,80-32). At 25 of these localities, ages derived from independent evidence such as radiocarbon dating, geological interpretation, and historical records were available for comparison and agreed well with the racemization ages. Some of these comparisons are listed in Table I. 

Hassan, A. A., Hare, P. E., Amino Acid Analysis in Radiocarbon Dating of Bone Collagen, In Archaeological Chemistry II, p. 109-116, Washington, D.C., American Chemical Society, 1978. 

Bada, J. L., Master, P. M., Hoopes, E., Darling, The Dating of Fossil Bones Using Amino Acid Racemization, In Radiocarbon Dating, pp. 740-756, Berkeley, University of California Press, 1979. 

This work demonstrated that AAR could give reasonable dates from smaller samples of bone than were necessary for radiocarbon, and had a time depth of at least 70 000 years, and possibly more if one of the more slowly racemizing amino acids such as alanine was used. The key paper came in 1974 (Bada et al., 1974), which published dates of between 6000 and 48 000 BP for various samples of human bone from the Californian coast (Table 8.1). The SDM (San Diego Museum) samples from site W-2 were from a shell midden near La Jolla excavated in 1926. Subsequently, it appears that 19 individual burials were recovered in a rescue operation from this site, known as La Jolla Shores SDM-16755 is thought to refer to more than one individual (La Jolla Shores I and II), with a third (La Jolla Shores III) identified as SDM-16740 (Taylor et al., 1985 Table 8.1). Site W-34 was located between Del Mar and Solano Beach, from a shell midden which had been largely destroyed by coastal... 

As a result of these inconsistencies, the very same amino acid extracts that had been used to produce the contentious AAR dates were independently dated by the AMS method at the Oxford Radiocarbon Accelerator Unit of the Research Laboratory for Archaeology and the History of Art, University of Oxford (OxA numbers Bada et al., 1984) and the NSF Accelerator Facility for Radioisotope Analysis, University of Arizona, Tucson (AA numbers). 

Tripp, J.A., McCuUagh, J.S.O., and Hedges, R.E.M. Preparative separation of underiva-tized amino acids for compound-specific stable isotope analysis and radiocarbon dating of hydrolyzed bone collagen. J. Sep. Sci. 2006, 29, 41-48. 

Amino Acid Analysis in Radiocarbon Dating of Bone Collagen... 

In this study, the modern and fossil bone collagen separated by dialysis is analyzed quantitatively for amino acids and the nitrogen/car-bon ratio to determine if the separated material is pure collagen or if it contains impurities which might aflEect radiocarbon dating. The fossil bone specimens with associated ages are Bison antiquus (10,000-11,000... 

In conclusion, nitrogen/carbon ratios combined with quantitative amino acid analyses could determine the level of impurities that may co-exist with fossil bone collagen and could help in selecting the optimum method of collagen separation. An extraction method may be successful in some cases but could fail to remove the impurities from bone collagen in other samples. Chemical analysis of the impurities and their radiocarbon dates also should be obtained. 

These various comparisons demonstrate that the Laguna skull radiocarbon date of 17,150 years is correct, that the dated Laguna material is indeed the original skull, and that the kasp value derived from the racemization and radiocarbon analyses of the Laguna skull can be used to calibrate the amino acid racemization reaction for the southern California coast. 

Radiocarbon Dating of Amino Acids Extracted from Chione Shell. We attempted to resolve the question of which dating method produced more accurate shell dates by submitting amino acids extracted from Chione shell for a radiocarbon analysis (20). Because of the possibility of exchange with groundwater carbonates, the inorganic carbon in mollusc shell can be contaminated easily. We reasoned that the carbon in the amino acids would provide a more reliable age estimate than the carbon-... 

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