Isolation of proline and hydroxyproline from fossil bone.

We describe a simple and rapid procedure for the isolation of proline and hydroxyproline from fossil bone based on the isolation of gelatin, hydrolysis, purification with XAD-2, deamination of primary amino acids with aqua regia, and separation of the imino acids by cation exchange chromatography. This procedure will provide material for accurate bone carbon dating, and stable carbon isotope ratio determinations for the evaluation of paleodiets.

Radiocarbon dates on bones of extinct birds from Hawaii.

Bones from a stratified sedimentary deposit in the Puu Naio Cave site on Maui, Hawaiian Islands, reveal the late Holocene extinction of 19 species of birds. The age of the sediment and associated fauna was determined by direct radiocarbon dating (tandem particle accelerator-mass spectrometer; TAMS) of amino acids extracted from bones weighing as little as 450 mg. The 14C dates indicate that sediment has been accumulating in the lava tube for at least the last 7750 years, a suitable time frame for testing the hypothesis that Holocene extinction on islands began after human colonization. Despite growing evidence that a worldwide wave of extinctions coincided with human colonization of oceanic islands, little radiometric data have been available to date the extinction of most small fossil vertebrates on islands. The TAMS technique of dating purified collagen from the bones of small vertebrates could lead to vastly improved chronologies of extinction for oceanic islands where catastrophic mid- to late-Holocene extinction is expected or known to have occurred. Chronologies derived from nonarcheological sites that show continuous sedimentation, such as the Puu Naio Cave deposit, may also yield key evidence on the timing of earliest human settlement of Oceania.

Holocene age of the Yuha burial: direct radiocarbon determinations by accelerator mass spectrometry.

The view that human populations may not have arrived in the Western Hemisphere before about 12,000 radiocarbon yr BP has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples. One such site is the Homo sapiens sapiens cairn burial excavated in 1971 from the Yuha desert, Imperial County, California. Radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21,500 +/- 1,000 yr BP, while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22,125 +/- 400 and 19,000 +/- 3,000 yr BP, respectively. The late Pleistocene age assignment to the Yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region, on the basis of the site's geomorphological context and from radiocarbon analyses of soil caliches. In rebuttal, arguments in defence of the original age assignment have been presented as well as an amino acid recemization analysis on the Yuha skeleton indicating an age of 23,600 +/- 2,600 yr BP. The tandem accelerator mass spectrometer at the University of Arizona has now been used to measure the ratio of 14C/13C in several organic and inorganic fractions of post-cranial bone from the Yuha H. sapiens sapiens skeleton. Isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4,000 yr BP. These results indicate that the Yuha skeleton is of Holocene age, in agreement with the cultural context of the burial, and in disagreement with the previously assigned Pleistocene age of 19,000-23,000 yr.