The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Regional variation in the cross-sectional geometric properties of southern African Later Stone Age foragers: an examination of humeri from three distinct ecoregions


Department of Anthropology, University of Toronto

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Diaphyseal cross-sectional geometry can be used to infer volitional activity patterns in archaeological populations. This study re-examines the cross-sectional geometric properties of Later Stone Age (LSA) African Cape coast forager humeri from the forest and fynbos ecoregions, previously assessed by Stock and Pfeiffer (2004). The sample size was increased (n=35m,30f), and specimens from the inland succulent karoo ecoregion were added to the analysis (n=4m,13f). Diaphyseal robusticity (J) and circularity (Ix/Iy and Imax/Imin) were quantified at the mid-distal (35%) location of humeri using the periosteal mould technique.

The majority of Stock and Pfeiffer’s (2004) results were replicated. Forest and fynbos females display relative symmetry in J, and increased antero-posterior (AP) relative to medio-lateral (ML) strengthening. Males have higher J values than females, and the fynbos population has higher J values than the forest population. Females likely participated in low intensity activities that create AP loading while males participated in high intensity activities with relatively equivalent AP and ML loading. Unlike the original study, forest and fynbos male bilateral asymmetry values are similar, indicating that males in both ecoregions experienced similar activity regimes, and forest females display increased bilateral symmetry, suggesting that they participated in more bilaterally symmetrical activities than fynbos females. The succulent karoo population has J values similar to the fynbos population, however both sexes display increased AP strengthening, indicating similar loading patterns and activity types in both sexes. These results suggest that regional variation in cross-sectional geometry may be related to the ecological and cultural factors affecting forager populations.

This study was funded by the Social Sciences and Humanities Research Council, grant 766-2012-1085.

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