Long bone robusticity and subsistence behaviour among Later Stone Age foragers of the forest and fynbos biomes of South Africa

The robusticity of human long bone diaphyses can provide information about habitual behaviour among humans in the past. Mechanically relevant morphological variables include the strength of the diaphysis relative to body size, asymmetry between antimeres, diaphyseal shape, and sexual dimorphism in mechanical properties. This study compares the long bone robusticity of humeri, ulnae, femora and tibiae of Later Stone Age foragers from the forest and fynbos biomes of the southern African Cape region (n = 65:32m,33f) dated primarily to between 8000 and 2000 BP. Ecological differences between these biomes dictate variation in the terrestrial resource base, although marine contributions to diet are significant throughout the Cape. Female robusticity remains relatively homogenous between the forest and fynbos biomes, and is characterized by relative symmetry in strength characteristics between paired upper limb elements with antero-posteriorly strengthened diaphyses. This morphology is consistent with shellfish harvesting and the use of digging sticks throughout the Later Stone Age in these regions. Male lower limb robusticity is consistently high in both biomes, suggesting that high levels of terrestrial mobility were characteristic of male subsistence strategies. The forest biome males have higher levels of bilateral asymmetry in upper-limb robusticity than males of the fynbos biome. This morphology may correspond with increased unilateral loading resulting from a higher frequency of use of spear projectiles relative to bows and arrows, and greater exploitation of medium to large sized bovids. (C) 2004 Elsevier Ltd. All rights reserved.