The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

Human ribs six through nine: sexual dimorphism and seriation using geometric morphometrics


Anthropology, University of California, Santa Barbara

Thursday All day, Plaza Level Add to calendar

Though human ribs present a challenging case in terms of identifying sex and position in the ribcage, both are essential for thorough forensic investigations. The latter aspect is especially important for determining if trauma occurred to the chest and the sequence in which it occurred. In order to accurately do so, it is imperative to be able to seriate the ribs. This study presents an investigation of ribs six through nine, which are notoriously difficult to differentiate.

Semilandmarks were collected across the superior border of each rib (n = 42) with a Microscribe, producing a three-dimensional curve. Each curve was resampled in Rhinoceros to have the same number of semilandmarks, which were then submitted to generalized Procrustes analysis. In order to reduce the number of variables prior to canonical variates analysis (CVA), a principal components analysis was conducted and a reduced number of variables (principal components) were submitted to CVA. Cross-validation results for sex returned an accuracy of 82% correct reclassification, while for rib position results of 75% correct reclassification were returned.

Thus, a new method is available to not only sex human remains using ribs, but also an way in which to seriate ribs six through nine, which will allow for more accurate reconstructions of trauma and improve estimation of age based on ribs.

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