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


Sexual dimorphism in the lower vertebral column: a discriminant function analysis using contemporary skeletal series

ROBERT F. PASTOR.

Department of Anthropology, University of Oregon

Thursday All day, Plaza Level Add to calendar

This presentation expands on an earlier (2005) study that developed methods for sex assessment from twelfth thoracic (T12) and first lumbar (L1) vertebrae. Two contemporary skeletal collections (Dart, Maxwell) were used to evaluate population variation in vertebral dimorphism shown originally for older samples (Spitalfields, Terry).

A suite of metric characters consisting of fourteen diameters and dimensions was examined, including height and diameters of the vertebral body, and dimensions of facets and processes. The Dart sample (University of Witwatersrand) of 20th century South African Blacks consisted of T12/L1 vertebral pairs from 51 male and 51 female skeletons, while a smaller sample (24 males, 15 females) of contemporary European/Americans was measured from the Donated Forensic Collection of the Maxwell Museum (University of New Mexico). Significant sex differences were determined for 13 traits in T12s and 12 traits in L1s from the Dart sample (p < 0.05 to 0.001); and for 9 variables from Maxwell T12 vertebrae.

Not unexpectedly, equations developed in the original study performed poorly for sex attribution when tested on the more modern samples. Consequently, new discriminant functions were developed and evaluated. The results showed significant sex differences for both vertebrae in the Dart and Maxwell samples. Using T12 for example, Black males and females from the Dart collection were correctly sexed approximately 90% of the time using one to three measurements. Discriminant analyses of the Maxwell male and female sample yielded similar results although at slightly lower accuracies. These results confirm high dimorphism in the lower vertebral column.

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