J Archaeol Sci 32 (11)

The authors argue that, despite the significant strides made in archaeological understanding of the potential biases of the ``old wood'' effect in radiocarbon dating charcoal and wood samples (whereby the age of the wood may be significantly older than its use by humans), little emphasis has been placed on the possible impacts of dating old shell in archaeological deposits. Marine shell is commonly used for 14C dating in coastal areas around the world, including a growing emphasis on the dating of individual shell artefacts via Accelerator Mass Spectrometry (AMS). In dating shell artefacts, the authors have obtained several dates older than associated 14C dates for short-lived subsistence remains from the same deposits, including great disparities (>10,000 years) and more subtle differences (14C dates on a variety of materials, and proper calibration procedures.

Three databases (2,961 georeferenced archaeological sites, simulated climatic variables simulating a typical ``warm'' phase of the isotopic stage 3 (IOS3 project), and ethnographic of hunter--gatherers (HG)) were used to estimate the size, growth rate and kinetics of the metapopulation of HG during four periods of the Upper Palaeolithic in Europe. The size of the metapopulation was obtained by multiplying a demographic density (per 100 km2) by the size of the population territory of HG. Demographic density for each period was calculated by successively backprojecting a reference density obtained for the Late Glacial with inter-period growth rate of the archaeological sites. From the Aurignacian to the Glacial Maximum, the metapopulation remained in a positive quasi-stationary state, with about 4,400--5,900 inhabitants (95% confidence interval (CI95%): 1,700--37,700 inhabitants). During the Glacial Maximum, the metapopulation responded to the cold by moving the northern limits of its maximum expansion zone towards the low latitudes by 150--500 km from west to east; by concentrating in few refuge zones (mainly Périgord, Cantabria and the Ibérian coasts); and by becoming perhaps distributed in smaller groups than during the pre- and post-Glacial Maximum. The metapopulation reached 28,800 inhabitants (CI95%: 11,300--72,600) during the mid-Late Glacial recolonisation.