Question What Is the Sex
Initially, clothing provides clues to the determination of sex, but these clues may be misleading. Definitive determination must be based on a skeletal examination. If you find that your subject was wearing a brassiere and a skirt, you can usually, but not always, assume that you are dealing with a female (Figure 34). For identification of sex, it is important to see the subject in situ before the remains is moved. In a case from Chicago, careful excavation revealed a body with the bra hooked and in place around the rib cage. The material of the jeans worn by the victim had disintegrated, but the piping down the side was intact and the zipper was zipped and in the normal position. The clothing suggested that the subject was female. If the clothing fragments had been picked up and brought to the lab without the chance of seeing them in place it would have been impossible to tell if the subject had been wearing the clothes or if they were simply incidental findings at the scene.
- Figure 34 Detail of skeletonized remains showing the location of deteriorated clothing and a plastic bag. (Photo courtesy of R. B. Pickering.)
Unisex clothing has become popular and complicates identification. A flannel shirt and jeans will not separate males from females. Jewelry is often indicative of sex, but with both females and males wearing earrings, lip plugs, and other accessories, jewelry is not as certain as it used to be. Other pieces of evidence, such as pocket contents, handbags, wallets, and so forth, also may indicate the sex or possibly the identity of the deceased. However, even with proper analysis of evidence, determination of the sex still requires a detailed examination of the skeleton by a qualified anthropologist. Personal effects are suggestive, but not definitive.
Determination of sex in adolescents and younger children ranges from difficult to impossible. Just as the external sexual changes do not become pronounced until adolescence, so too, the differences in the skeletons of young boys and girls are not pronounced until children begin to become adults. Determining sex from skeletons of children is based on a statistical assessment of measurements of numerous bones, particularly the long bones of the arms, legs, and the bones of the pelvis. Essentially, all or most of the major bones must be present (Figure 35).
Several elements of the skeleton can be used by a physical anthropologist to differentiate sex in adults, but the pelvis is the most reliable bony element. An expert can determine sex using the pelvis with about 90 percent accuracy, but a wise expert will not rely on just one skeletal element for that determination. The differences in the male/female pelvis reflect the basic biological difference between men and women: women bear children, men do not. From the skeletal perspective, the female pelvis tends to be broader and shorter than the male pelvis and the female pelvis has a relatively larger interior diameter than the male pelvis (Figure 36). Males tend to have a higher, narrower pelvis. A complicating feature is that sexual dimorphism—the difference in size and robusticity—varies from population to population. This point has forensic implications. For example, American blacks and American whites have a high degree of sexual dimorphism. The skeletons of males generally are noticeably larger and more robust than those of females. Therefore, seeing the skeletal differences is easier. However, among Southeast Asian populations, sexual dimorphism is less pronounced and the differences in bone sizes are not so pronounced. As the American population includes more people from other parts of the world, specifically Southeast and South Asia, investigators need to be aware of these kinds of variations. A potential error could involve identifying a Southeast Asian male skeleton as an American female skeleton. Because of the population differences in sexual dimorphism, race or ethnicity must be determined before sex can be determined.
It is not unusual to have forensic and archaeological cases in which the determination of sex was not clear cut or the data seemed to be conflicting. Take the case of Wenu-hotep, the mummy of an ancient Egyptian who lived about 2,500 years ago and now resides in a midwestern museum.
- Figure 35 Bones of the pelvis are very important for determining age and sex from childhood to adulthood; both size and shape change. (Photo courtesy of R. B. Pickering.)
According to hieroglyphs on the coffin, the mummy was female. However, in Egyptology, checking to see if the mummy and the coffin actually go together is always necessary. Sometimes the ancient Egyptians put their relatives in other people's coffins and sometimes antiquity dealers put good mummies in good coffins to raise the selling price. On examining the full-body x-rays of Wenu-hotep, it was noted that the mandible was broad and the skull had a prominent brow ridge. Both these characteristics suggest that the person was male, not female (Figure 37). X-rays of the pelvis were inconclusive. Subjecting the wrapped mummy to a CAT scan solved the problem. The pelvis presented clear female characteristics. Moreover, the CAT scan was capable of creating images of the soft tissue. The presence of desiccated breasts and lack of male genitalia clearly defined the sex. Although this case is archaeological, it demonstrates the need to look at the entire skeleton, not just one or a few features. Table 2 identifies differences in the pelvis in males and females.
- Figure 36 Top, the male pelvis has a smaller pelvic inlet and generally is narrower than the female pelvis. Bottom, the female pelvis has a broad, rounded pelvic inlet and a broader sacrum, relatively. (Drawings courtesy of L. Schulzkump, MD.)
Figure 37 CAT scan reconstruction of the mummy Wenu-hotep suggests a face with a broad, masculine chin. However, soft tissue on the mummy definitely identified the sex as female. (Photo courtesy of R. B. Pickering.)
Figure 37 CAT scan reconstruction of the mummy Wenu-hotep suggests a face with a broad, masculine chin. However, soft tissue on the mummy definitely identified the sex as female. (Photo courtesy of R. B. Pickering.)
The skull is the next most reliable skeletal indicator of sex. Males tend to have larger and more rugged skulls than do females. Usually, a large supraorbital ridge, long and broad mastoid processes, and a rugged nuchal region of the occipital bone are indicators of the male sex. In contrast, female skulls are more gracile, meaning they do not present the heavy bony development of male skulls. As mentioned earlier, the mandible also represents sexual differences. Males tend to have broad, "squarish" chins while females have more "V-shaped" chins (Figure 38). Although the common wisdom is that the skull is the most important feature of the skeleton, using it alone to determine sex is much less accurate than using only the pelvis. Again, the best technique is to use all the available bones (Table 3).
Table 2 Sexual Characteristics of the Pelvis
Trait
Male
Female
Symphysis Subpubic angle Obturator foramen Sciatic notch Sacroiliac articulation Ilium Sacrum Pelvic inlet Acetabulum
High, narrow V-shaped
Large, ovoid Narrow, deep Large, straight High, vertical
Heart-shaped Large
Long, narrow, straight
Low, wide U-shaped, round Triangular Wide, 70-90 degrees Small, oblique Wide
Short, broad, curved Circular, elliptical Small
Modified with permission from Krogman, M. M. & e Human Skeleton in Forensic Medicine, 2nd ed., Springfield, IL: Charles C Thomas, 1973, 129.
Long bones also differ between males and females; however, the differences are subtle and are identified primarily through measurements and statistical analysis. Both the length and diameter of the bones are measured and, when compared to charts derived from many skeletal measurements, can give an indication of sex. Experience is the only way to learn to accurately make those measurements. The diameters of the heads of the humerus and the femur have been shown to be very useful. Unfortunately, these parts of the skeleton are delicate and are often damaged if not properly handled.
Unfortunately, the pelvis and skull are not present in every forensic case. If these bones are not available, the determination of sex is going to
Figure 38 The skull on the right has a smoother, more rounded vault and a smaller chin; it is female. The more rugged skull on the left has male characteristics. (Drawing courtesy of L. Schulzkump, MD.)
Figure 38 The skull on the right has a smoother, more rounded vault and a smaller chin; it is female. The more rugged skull on the left has male characteristics. (Drawing courtesy of L. Schulzkump, MD.)
|
Trait |
Male |
Female |
|
Supraorbital ridge (ridge above the eyes) |
Robust |
Gracile |
|
Occipital protuberance (base of skull) |
Robust |
Gracile |
|
Mastoid processes (bony process behind |
Long, broad |
Short |
|
ear canal) | ||
|
Chin |
U-shaped, square |
V-shaped |
Modified with permission from Krogman, M. M. & e Human Skeleton in Forensic Medicine, 2nd ed., Springfield, IL: Charles C Thomas, 1973, 115.
Modified with permission from Krogman, M. M. & e Human Skeleton in Forensic Medicine, 2nd ed., Springfield, IL: Charles C Thomas, 1973, 115.
be tentative, not definite. In such cases, the forensic anthropologist will use as many techniques as necessary to make the determination. In some cases, DNA testing for sex may be appropriate. However, if there are no clear results, it is better to acknowledge this rather than to force the skeleton into one sex or the other, as forcing the determination may cause an error.
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