Quantifying Dominance: An analysis of humeral bilateral asymmetry and implications for behavioral reconstruction
A commonly cited characteristic of the human species, the concept of handedness represents a persistently enigmatic notion in modern society. Although important because the genesis of both handedness and language can be attributed to cerebral hemispheric lateralization in our evolutionary past, this feature remains ill defined and consequently defies analysis. Emerging CT technology, however, enables the application of morphometric techniques to human long bones, facilitating the quantification of bone’s internal mechanical properties as a possible way to improve the assay of bilateral asymmetry in the humerus. This capacity was applied to the population of Hasanlu, a Bronze Age site in which archaeologists posited a sexual division of labor among inhabitants as the result of artistic and botanical evidence. This division would have had males engaging in lateralized activities such as engaging in battle with spears or farming occupations while the females dedicated their time to the rigorous bimanual task of wheat processing. Because of this, internal mechanical properties within the humeri of males and females were postulated to exhibit differences in the distribution of mechanical loading. Indeed, analysis found a significant degree of lateralization only in the midshaft of the male humerus, supporting the idea that the inhabitants of Hasanlu did engage in division of labor based on sex.