Directional Asymmetry and Hand Dominance in Colonial Mexico City

Abstract

This project explores the under-studied phenomenon of directional asymmetry with regard to hand dominance, using radiographs of left and right metacarpals from the burial population at the colonial Hospital Real San Jose de los Naturales, in present day Mexico City. Bilateral asymmetry has recently become a more popular area of research within bioarchaeology, but is still relatively new and includes a small number of studies. There has also been very little bioarchaeological research using populations in the Americas, relative to the amount of research using European populations. Using radiographs of the second metacarpals of 73 individuals from Colonial Mexico, the percent of directional asymmetry was calculated and analyzed in order to determine rates of hand dominance and potential differences between the sexes. The results of this study show distinct right-left asymmetry for several measures across the entire sample, namely total length and head width. The data also show that while most of the sample was likely right-hand dominant, there is a portion of the population with clear left-bias, suggesting that the second metacarpal will be larger on the right or left side depending on hand dominance and biomechanical stress.