Masters Theses

Date of Award

5-2000

Degree Type

Thesis

Degree Name

Master of Arts

Major

Anthropology

Major Professor

Murray K. Marks

Committee Members

Lyle W. Konigsberg, Walter Klippel

Abstract

Sex estimation has long been of interest to researchers in the fields of physical and forensic anthropology. Over time, sexing methods have evolved from a strict reliance on morphological traits to the emergence of metric and statistical analyses. After years of focusing exclusively on the cranium and pelvis for the sexing of human skeletal remains, anthropologists have recently begun basing their sex predictions on indicators seen in bones of the postcranial skeleton, such as the femur, sternum, and sternal ends of the ribs.

The goals of this study include: 1. examining of the relationship between sex and the dimensions of the forearm bones, 2. developing a method for estimating the sex of an unidentified case from measurements of the radius and ulna, and 3. statistically assessing the usefulness of these bones for sex estimation in a modem population.

Sex estimating ability of the forearm bones was investigated in a skeletal sample (N=165) of modern U.S. whites and blacks of known sex. The research involved the collection of various measurements from the left and right radii and ulnae of each skeleton. The metric data was then analyzed using the S AS program. Statistical analyses identified the greatest discriminating variables for each side and calculated the linear discriminant functions for sex estimation. A crossvalidation procedure was employed to test the accuracy of the functions for sex classification.

Results indicate that different measurements have stronger sex discriminating capacities for the left and right sides. This difference may be due to the effects of handedness on the population. Left handedness is seen in only a small percentage of the world population (approximately 10%) and occurs more often in males. The role of handedness remains a point of interest for this study. However, the factors that determine handedness are far from understood. Although several theories have been proposed to explain handedness, none have been conclusively proven. Obviously, additional research is necessary to examine any definite correlation between handedness and the sexing potential of the upper limb bones.

Based on the statistically significant crossvalidation results, this research contends that this sexing method could be beneficial to physical and forensic anthropologists. The sexing function for each side shows a high degree of accuracy indicating usefulness for an investigator faced with the daunting task of identifying an unknown case's sex from only the left or right arm bones. A more accurate sex estimation can be obtained by applying a discriminant function for a particular side to a bone from the same side. In addition, the use of only the radius and ulna for this study shows that this method could be extremely significant for sex identification in fragmentary or dismembered skeletal remains, in which more traditional indicators (i.e. pelvis, cranium) are absent. unidentified case from measurements of the radius and ulna, and 3. statistically assessing the usefulness of these bones for sex estimation in a modem population.

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