Landscapes, climate change & forager mobility in the Upper Paleolithic of northern Spain

Numerous studies have shown that the relative frequency of retouched pieces can help to distinguish forager mobility strategies amongst individual layers at a single site and, potentially, at multiple sites across regions (Riel-Salvatore & Barton, 2004; Riel-Salvatore et al., 2008; Barton & Riel-Salvatore, 2014). We use this proxy measure and other lines of evidence to evaluate Late Pleistocene human land-use practices from 47 Upper Paleolithic and Mesolithic sites in northern coastal Spain. To monitor mobility strategies we examine the proportion of retouched pieces to total lithics, focusing on backed pieces which probably served mostly as replaceable inserts in organic armatures for hunting weapons. Kuhn (1995) argued that foragers at some distance from a residential base would have had to rely on replaceable elements for the tools and weapons they carried with them. Assemblages with low total lithic densities but a high proportion of backed pieces would most likely represent the remains of short-term camps where hunting weapons were repaired in the field, whereas those with high lithic densities and relatively few backed pieces would likely represent residential bases where hunting weapons were manufactured. The analysis also links variation in lithic assemblages to paleoclimate and topography and uses 951 radiocarbon dates to identify demographic ‘pulses’ under the assumption that – ceteris paribus – the density of dates and the density of population are at least roughly linearly correlated with one another (French & Collins, 2015). Increases and decreases in regional population density can be detected and compared to episodes of climate change measured by the GISP2 and NGRIP2 ice cores over the Pleniglacial, Tardiglacial (MIS 2) and the early Holocene. Data insufficiencies, incomparable typologies, and adequacy of reporting are also discussed.