Direct dating fossils


20-Jun-2017 17:10

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We applied zooarchaeology by mass spectrometry (Zoo MS) to find additional hominin remains.We identified one bone that is Neanderthal, based on its mitochondrial DNA, and dated it directly to 46,200 ± 1,500 B. We also attempted to date six early Upper Paleolithic bone points from stratigraphic units G. in Europe witnessed the so-called biocultural transition from the Middle to early Upper Paleolithic, when incoming anatomically modern humans displaced Neanderthal groups across the continent (1, 2).Radiocarbon dating of Neanderthal remains recovered from Vindija Cave (Croatia) initially revealed surprisingly recent results: 28,000–29,000 B. This implied the remains could represent a late-surviving, refugial Neanderthal population and suggested they could have been responsible for producing some of the early Upper Paleolithic artefacts more usually produced by anatomically modern humans.This article presents revised radiocarbon dates of the human bones from this site obtained using a more robust purification method targeting the amino acid hydroxyproline.All dates obtained on the four Neanderthal specimens at the ORAU are reported in Table 2.We also list the dates obtained on two other hominin samples: Vi-75-G3/h-203, analyzed at the Uppsala Radiocarbon Laboratory (Sweden) (23), and Vi-2291-18 (level G, sublayer unknown), prepared at the Max Planck Institute, Leipzig, and dated at the ORAU (24).Because of lower endogenous DNA content in Vi-208, a full mitochondrial genome could not be reconstructed for the sample.However, from the limited amounts of mitochondrial sequences, we were able to trace most of the observed variants to variations found in previously sequenced Neanderthal mitochondrial genomes (Nine of the samples selected produced enough collagen (or hydroxyproline) to be dated by AMS.

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Full mitochondrial genomes of Vi-207 and Vi-*28 were reconstructed with an average coverage of 103-fold and 257-fold, respectively.We also included the sample from a split-based bone point (Vi-3437) that had been analyzed in the laboratory previously, producing only a small collagen yield.We decided to attempt to redate it, using a larger starting mass of bone powder.The initial radiocarbon results were 29,080 ± 400 B. In addition to the Neanderthal remains, level G has yielded a small archaeological assemblage that contains techno-typologically Middle and Upper Paleolithic lithic artifacts plus several distinctively early Upper Paleolithic osseous points (12).

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It has been argued that the mix of Neanderthals, Middle Paleolithic tools, and Upper Paleolithic technology was the result of cryoturbation and lithic assemblage has parallels with the Szeletian technocomplex, and further, that there is a mixture of elements of Szeletian and Aurignacian I and II within the level [see also Svoboda (18)].

The latest data, both radiometric and genetic, suggest Neanderthals and modern humans coexisted or overlapped for up to several thousand years in Europe until Neanderthal disappearance at around 40,000 cal B. Our understanding of the biocultural processes involved in the transition have been greatly influenced by improved accelerator mass spectrometry (AMS) dating methods and their application to directly dating the remains of late Neanderthals and early modern humans, as well as artifacts recovered from the sites they occupied. (10) showed that, when redated using ultrafiltration methods, the bones that produced ages of ∼33,000 B. were in fact beyond the radiocarbon limit, suggesting the Neanderthal remains were unlikely to be as young as previously thought. For sample Vi-208, after ultrafiltration, the C/N atomic ratio was 3.4, which indicates collagen of acceptable quality.