Monday, October 25, 2010

Sexing Skeletons

This is a short overview of the problems related to telling the sex of skeletons, written by Christie Ward and posted originally to Norsefolk. (This relates back to the last posting here.)

Christie has a well earned reputation for clear analysis and careful referencing of her articles and comments. Any question she fields most usually is backed up with an extensive set of links and book references. She has gathered together years of short articles related to the Viking Age on her web site 'The Viking Answer Lady'. A highly recommended resource for my readers!

Sexing a skeleton is not simple, even if you have a pretty intact example. the pelvis, based on the need for women to have babies, gives the best sexing information. However, on skulls, it really comes down to "how butch does this skull look to me?"

If you have the whole pelvis, then visual inspection can determine the sex about 90% of the time. But when you have less than a whole pelvis, the identification can be a
lot more difficult. It's almost impossible to determine the sex from the bones of a prepubertal child.

http://tinyurl.com/PelvisByGender
A pelvis is determined to be male if: the subpubic angle is less than 90°; the pubic shape is triangular; the shape of the subpubic angle is convex; the greater sciatic notch is less than 68°, and the sacrum is small and more curved.
A pelvis is determined to be female if: the subpubic angle is greater than 90°; the pubic shape is rectangular; the shape of the subpubic angle is concave; the greater sciatic notch is greater than 68°, and the sacrum is larger and straighter.
Forensic anthropologists can accurately identify sex from a complete skull between 85% and 90% of the time. The success rate goes down if you are missing pieces. As I mentioned above, skull sexing is really more subjective than pelvic sexing, because it assumes that men are square-jawed, beetle-browed, and muscular -- and that women aren't -- which is not always the case. Notice too that the pelvic criteria have some firm mathematical tests, while the skull criteria are more subjective.

A skull is determined to be male if: the chin is square; the angle of the ascending ramus is close to 90°; the root of the zygomatic arch is likely to extend beyond the auditory meatus; the mastoid process is large; the external occipital protuberance is prominent; there is a rough, robust skull; there are marked muscle lines; the forehead is receding; the brow ridges are prominent; there are rounded orbital margins.
A skull is determined to be female if: the chin is rounded; the angle of the ascending ramus is obtuse; the root of the zygomatic arch is not likely to extend beyond the auditory meatus; the mastoid process is small; the occipital protuberances are poorly developed; there is a smooth, gracile skull; the muscle lines are not prominent; there is a vertical forehead; the 'brow ridges' are absent or are poorly developed; The orbital margins are sharp.
Also note that in older archaeological reports no skeletal sexing may have been done -- they likely attributed sex based on grave goods.
Content in quotes copyright Christie Ward © 2010. Used with permission.

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