A diachronic examination of biomechanical changes in skeletal remains from Tombos in ancient Nubia

Using morphometric assessment, we diachronically analyse mechanical stress and limb function at the Tombos (modern Sudan) archaeological site through time and changing socioeconomic circumstances. Based on previous research, we expect that during the Third Intermediate/Napatan (c. 1070-656 BCE) people were larger and more physically active than in the New Kingdom (∼1400-1070 BCE). On the appendicular skeleton of adults 57 measurements were obtained on individuals from 67 discrete burials and 370 commingled skeletal elements. These raw measurements were analysed statistically. Individuals from the discrete burials were used to calculate body mass and estimate mechanical behaviour (torsional and bending rigidity of long bones) modeled using beam theory across several bones of the upper and lower limbs. Body mass estimates for both sexes show people during the Third Intermediate/Napatan period were statistically significantly larger. On the upper limb for both sexes, variation reflects joint stabilisation and actions of flexion and extension at the elbow and/or supination/pronation of the forearm. On the lower limb, females show variation related to weight bearing activities and foot flexion; male variation is related to weight bearing activities, joint movement and stabilisation. These data point to altered habitual behaviour and physical activity for both sexes at Tombos through time. Suggested causes for both sexes include increased agricultural activities, and for males increased granite quarrying and equestrian activities. Using analyses of multiple bones of the upper and lower limbs in conjunction with biomechanical analyses, this study demonstrates the importance of the examination of physical activities in past populations, highlighting changes that can occur with sociopolitical transitions.