Biology Reference
In-Depth Information
dimorphism are found in the femur across all populations with vastly different activity
patterns, then confidence increases that the dimorphic traits are the result of universal sex
differences in the shape of the pelvis and not the result of population-specific activity
patterns.
The entire skeleton is under varying amounts of intrinsic and extrinsic influences. According
to Ruff (1987), biological anthropologists have focused on statistical techniques for differenti-
ating sexes, without considering these functional aspects. If we are able to recognize not only
biological differences but biomechanical differences as well, we may learn to better understand
sexual dimorphism in humans and improve sex discrimination from the skeleton. I explain the
functional adaptations of the skeleton in greater detail in the later chapter on functional
morphology in this volume (Chapter 14). The following discussion of the various methods of
sex estimation and sex assessment is not meant to be exhaustive, but intended to be a starting
point for young researchers to develop interest in sexing from the human skeleton.
SEX ASSESSMENT
Sex Assessment: Pelvis
The anatomical illustration by Edward Mitchell published in 1819
4
demonstrates an early
understanding of sexual dimorphism in the human pelvis (
Figure 4.1
). Several aspects of the
female pelvis begin to change shape at puberty to accommodate the birth of a human infant's
relatively large skull. For example, the pubic bone broadens, the pubic ramus thins and
lengthens, and the auricular surface becomes slightly raised. The angle of the sciatic notch
and the subpubic angle become obtuse. While these traits are difficult to quantify metrically,
the visual observations are immediate and require no equipment, only knowledge and expe-
rience. Many texts offer descriptions and diagrams for sex assessment from the pelvis (
Broth-
well, 1963; Stewart, 1979; Krogman and I¸can, 1986; Bass, 1987; Rogers, 1987; Buikstra and
Ubelaker, 1994; White et al., 2012
).
In general, the female pelvis develops at puberty to have a broader inlet, whereas the male
pelvis follows the preadolescent pattern, as shown in
Figure 4.2
. Thus, if sexing a subadult
pelvis (possibly as young as 12 or 13), if there are female traits present, the researcher can
be confident that it is in fact female. If, however, the traits seemmasculine, the juvenile could
be either female or male (
Buikstra and Ubelaker, 1994
). In Standards for Data Collection From
Human Skeletal Remains (
Buikstra and Ubelaker, 1994
), only three methods for sex assessment
from the pelvis are recommended: (1) the Phenice method of subpubic morphology, (2) the
morphology of the greater sciatic notch, and (3) the presence of the preauricular sulcus, all of
which are combined into the study by
Bruzek (2002)
, yielding high classification accuracy
rates, as discussed below.
The Phenice method is a visual sex assessment method of the anterior os coxa that exam-
ines the traits of the subpubic concavity, the medial ischiopubic ramus and the ventral arc, with
sexing accuracy rates in excess of 95% according to the author (
Phenice, 1969
).
Phenice
4
The Mitchell engraving is based on illustrations done by the early skeletal biologist and anatomist Jean
Joseph Sue (1710
e
1792).
