New data on Late Upper Paleolithic upper limb cross-sectional geometry from Arene Candide: implications for Tardiglacial hunting practices

European Late Upper Paleolithic people display levels of bilateral asymmetry in humeral mechanical strength comparable to professional tennis players. This highly-characteristic trait has been associated with the use of throwing weapons to “kill at a distance”, an activity that likely required extensive training that began at a young age. Previous studies have pooled European samples to increase sample size. This pooling may have masked regional behavioral variation associated with the fragmentation of populations during the Tardiglacial period (ca. 16-10,000 BP). We collected new data on upper limb (humerus and ulna) bilateral asymmetry for torsional robusticity (via cross-sectional geometry) on four adult males (AC 2, 3, 4, 12) and one adolescent (13 y.o., AC 16) from Arene Candide (northwestern Italy). Results indicate that all adult individuals show high levels of mid-distal humeral bilateral asymmetry (40% to 110%). Ulnar asymmetry was less pronounced (50% in two individuals, 5% in the remaining two). Despite the expectations of an early onset of throwing behavior, the adolescent individual displayed low humeral (12%) and ulnar (16.5%) asymmetry. Conversely, an adult with congenital x-linked ypophosphatemic rickets displayed high humeral asymmetry (40%). The genetic disorder affecting this individual resulted in low stature, diffused enthesopathies, and bowing deformities, which likely affected his ability to perform high-mobility tasks. Yet, results are suggestive of highly-asymmetrical upper limb torsional loadings, which may indicate participation in throwing behavior. The study of functional adaptations of physically-impaired prehistoric individuals may contribute to the understanding of how they integrated into the subsistence practices of their group.