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


Sternal Rib End Age Estimation: Asymmetry and Proxy Ribs

KEVIN B. HUFNAGL and DONNA M. MCCARTHY.

Department of Anthropology, University of Tennessee

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Skeletal age estimation is a common procedure in archaeology and forensic anthropology. Sternal rib ends are used in conjunction with the pubic symphysis and the auricular surface for age estimation. This presentation examines the similarities between the left and right rib ends and between the third, fourth, and fifth ribs. We hypothesize that all six ribs ends being investigated will be in general agreement with respect to their morphologies.

In this study, 176 sets of ribs from the William M. Bass Donated Collection were scored. The third, fourth, and fifth ribs of both sides were scored using both male and female nine-phase methods as well as three components of rib morphology. All observations were recorded by the first author.

Seven comparisons were made for each of the five variables for a total of 35. These comparisons were analyzed using simple mathematical calculations and Wilcoxon Rank Sum tests for directionality of the differences. All comparisons show a moderate amount of disagreement between ribs ranging in frequency from 10 to 40%. The variable “pit depth” performs the worst. The fifth rib surpasses the others in terms of symmetry and agrees with the fourth more often than the third.

This study shows that not all sternal rib ends have the same morphological expression. Based on our results the fifth rib is better than the third as a proxy for the fourth. It may even be a more stable age indicator than the fourth rib.

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