J Archaeol Sci 31 (9)

Molecular analysis of DNA preserved in archaeological bone allows bypassing of certain palaeontological biases. Studies of DNA in fossils are based on the PCR amplification of the small number of molecules that have not been destroyed over time by diagenetic processes. The sensitivity of the method, the presence of polymerase inhibitors in the fossil extracts, the small number of authentic ancient DNA molecules, and their numerous chemical modifications render this powerful approach unreliable and have led to many controversies. The authors argue that real-time PCR is the method of choice to assess the initial number of genuine ancient DNA molecules in the extracts, the effect of inhibitors and the presence of low concentrations of contaminating modern target molecules, and suggest that this methodology will help to identify contaminations, to better interpret PCR results and to render ancient DNA studies more reliable.

The 14C community has undertaken a programme of inter-comparisons, for the benefit of laboratories and users alike, the most recent being completed in 2001. The information arising from the studies is important for the appropriate interpretation of the scientific evidence provided by 14C analyses in calibration and construction of chronologies where assemblages of dates are frequently assessed. In this paper, some preliminary findings from the Fourth International Radiocarbon Inter-comparison, completed in 2001, are reviewed and some conclusions drawn with regard to accuracy and precision of 14C dates.

The formation of authigenic minerals in cave sediments can be used to reconstruct the paleochemical conditions that prevailed in the past. The authors investigated contemporary bat guano deposits in caves and the sediments directly below such deposits. The emerging patterns show that the formation of authigenic minerals occurs under acidic conditions within tens of years. Periods of cave abandonment can be inferred from the presence of authigenic minerals in the sediments as it is during these times that bats mainly occupy the cave.

Although a small number of studies have attempted to introduce automatic grouping procedures into thin section petrography of archaeological ceramics, the majority of studies continue to be carried out by non-automatic means. Although such an approach with the single observer grouping samples has a number of advantages, it is problematic when dealing with large numbers of samples. This paper aims to explore different coding systems and statistical analyses for grouping ceramic thin sections. In the example discussed a number of variables are defined, codified and analysed by correspondence analysis, classical multidimensional scaling, non-metric isotonic multidimensional scaling and Sammon mapping. The group separation is compared between methods and with previous non-automatic grouping of the same material. The results are promising for this approach, which can be adapted for different studies by the redefinition of the variables recorded and analysed. Includes