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Smithsonian National Museum of Natural History
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Bone Basics


An Inside Look at Bone
Young or Old?
Male or Female?
Human or

How do investigators and scientists tell if a bone
or skeleton belongs to a man or a woman? The clues lie in the bones themselves.


A skeleton's overall size and sturdiness give some clues. Within the same population, males tend to have larger, more robust bones and joint surfaces, and more bone development at muscle attachment sites. However, the pelvis is the best sex-related skeletal indicator, because
of distinct features adapted for childbearing. The skull
also has features that can indicate sex, though slightly less reliably.

Clues in the Pelvis

[Left] Male pelvis. [Right] Female pelvis.

[Left] Male pelvis.  [Right] Female pelvis.
Image courtesy: Smithsonian Institution

This table outlines the differences between a male and female pelvis.



  • narrower, heart-shaped pelvic inlet
  • open, circular pelvic inlet
  • narrower sciatic notch
  • broader sciatic notch
  • narrower angle where the two pubic bones meet in front
  • wider angle where the two pubic bones meet in front
  • more outwardly flared hip bones


  • Sex-related skeletal features are not obvious in children's bones. Subtle differences are detectable, but they become more defined following puberty and sexual maturation.

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