Which skeletal element is most reliable for sex estimation in adults, and which features contribute most to accuracy?

• A. The pelvis; subpubic concavity, ventral arc, the shape of the pelvic inlet, and the greater sciatic notch
• B. The skull; mastoid process size, supraorbital ridges, nuchal crest
• C. The scapula; glenoid cavity size and acromial shape
• D. The femur; neck-shaft angle and femoral head diameter

Answer: (A)

The key idea is that the pelvis provides the most reliable clues for adult sex estimation because its bones undergo pronounced, sexually dimorphic adaptations related to childbirth, producing more consistent differences between males and females than other bones.

In practice, the most informative pelvic traits are the subpubic region and the ventral arc. A more pronounced ventral arc and a deeper subpubic concavity are typical of females, reflecting pelvic remodeling for childbirth. The shape of the pelvic inlet also offers strong separation: females tend to have a wider, more oval inlet, whereas males have a narrower, heart-shaped inlet. The greater sciatic notch is another reliable indicator, being wider in females and narrower in males. Taken together, these pelvic features provide the strongest overall accuracy for sex estimation in adults because they display clear, population-relevant dimorphism that remains robust across preservation states and is less prone to overlap than features from other bones.

Skull features like the mastoid process, supraorbital ridges, and nuchal crest can be sexually dimorphic but generally show more overlap between sexes and greater population variation, making them less reliable than pelvis-based assessments. The scapula and femur can offer clues, but their dimorphism is subtler and more influenced by factors like activity or age, so they contribute less to accuracy than pelvic traits.