This is the 2nd blog post in this Quick Tips series on estimating the biological sex of human skeletal remains. If you haven’t read the first post on the basics of sexing skeletal remains, click here to start at the beginning.
One of the most widely used methods of sexing skeletal remains is by examining the skull. The skull has five different features that are observed and scored. The five features are the:
Each of these markers is given a numerical score from 1 to 5 relating to the level of expression, with 1 being minimal expression and 5 being maximal expression. Each feature should be scored independently, and without influence from the other identifying features. It has been generally found that female skulls are more likely to have a lower level of expression in all features, whereas male skulls are more likely to have higher levels of expression.
To observe the nuchal crest, one should view the skull from its lateral profile and feel for the smoothness (1-minimal expression) or ruggedness (5-maximal expression) of the occipital surface, and compare it with the scoring system of that feature (Figure 1).
Figure 1: The scoring system for expression levels in the nuchal crest.
To observe the mastoid process, one should view the skull from its lateral profile and compare its size and volume, not its length, with other features of the skull such as the zygomatic process of the temporal lobe and external auditory meatus. Visually compare its size with the scoring system of that feature (Figure 2). If the mastoid process only descend or projects only a small distance then it should be scored a 1 (minimal expression), where as if it is several times the width and length of the external auditory meatus, then it should be scored as a 5 (maximal expression).
Figure 2: The scoring system for the expression levels of the mastoid process.
To observe the supraorbital margin, one should view the skull at it’s lateral profile and place their finger against the margin of the orbit and hold the edge to determine it’s thickness. If the edge feels ‘extremely sharp’ then it would score a 1, minimal expression, if it felt rounded and thick as a pencil it would score a 5, maximal expression (Figure 3).
Figure 3: The scoring system for the expression levels of the supraorbital margin.
To observe the supraorbital ridge, one should view the skull from it’s profile and view the prominence of the supraorbital ridge. If the ridge is smooth with little or no projection, then it would score a 1, minimal expression, if it is pronounced and forms a rounded ‘loaf-shaped’ ridge then it would score a 5, maximal expression (Figure 4).
Figure 4: The scoring system for the expression levels of the supraorbital ridge.
To observe the mental eminence, one should view the skull front facing, and hold the mandible between the thumbs and index fingers, with the thumbs placed either side of the mental eminence. If there is little or no projection of the mental eminence, then it would score a 1, minimal expression, if it is pronounced it would score a 5, maximal expression (Figure 5).
Figure 5: The scoring system for the expression levels of the mental eminence.
Buikstra, J.E., Ubelaker, D.H. 1994. Standards for Data Collection From Human Skeletal Remains. Fayetteville, Arkansas: Arkansas Archaeological Survey Report Number 44.
Ubelaker, D.H. 1989. Human Skeletal Remains: Excavation, Analysis, Interpretation (2nd Ed.). Washington, DC: Taraxacum.
White, T.D., Folkens, P.A. 2005. The Human Bone Manual. San Diego, CA: Academic Press. Pg 360-385.
This is the second post of the Quick Tips series on sex determination of skeletal remains. The next post in this series will focus on the use of the pelvis and parturition scars to determine biological sex. To read more Quick Tips in the meantime, click here!