Activity patterns in Upper Paleolithic and Neolithic Western Liguria: a diachronic analysis

The long prehistoric record of Liguria (Italy) affords an excellent opportunity to study differences in activity patterns across environmental and subsistence changes. Geometric analysis of long bone structure can yield important information about the effects of mechanical forces applied to the skeleton throughout life. This information can in turn be used to infer habitual subsistence and technological behaviors. This approach was used to track patterns of upper and lower limb robusticity in samples of early (EUP) and late (LUP) Upper Paleolithic and Mesolithic European skeletons, comprising material from all over Europe as well as Liguria. In addition, the analysis included a sample of Neolithic Ligurian skeletons. Between EUP and LUP, patterns of upper limb robusticity show distinct trends: humeral strength and asymmetry increase, particularly in males, while cross-sectional shape becomes more circular. These changes reflect increased levels of stressful manipulative behaviors and unimanual activities, perhaps involving a higher prevalence of throwing, rather than thrusting. When articulated with faunal evidence, these results suggest an increase in diet breadth, based in part on resources associated with higher handling costs. The Ligurian Neolithic sample shows a further increase in male upper limb strength, in particular on the left side, resulting in decreased asymmetry. The decreased lateralization may be tied to activities associated with pastoralism, well documented in the archeological record. Lower limb robusticity decreases between EUP and LUP, suggesting a significant decline in mobility, in keeping with archaeological evidence of increased regionalization and territoriality after the Last Glacial Maximum. Lower limb robusticity decreases further during the Mesolithic. Interestingly, the Neolithic Ligurian males, while less robust overall than Upper Paleolithic and Mesolithic males, exhibit levels of antero-posterior bending strength analogous to that found in LUP males, perhaps reflecting the effects of the mountainous terrain exploited by these pastoralists. This study demonstrates the usefulness of long bone geometric structural analysis, which, when articulated with archaeological evidence of subsistence, provides important information about changing patterns of prehistoric biocultural adaptation.