Because of this density, and because of a peculiarity of the inner ear tissue that causes bone cells from that region to be incorporated into the petrous bone matrix during development, the petrous bone contains an unusually high concentration of DNA from bone-forming cells.

This DNA is physically protected by the dense mineral matrix, shielded from water and bacteria to a degree that other bones cannot match.

Paleogeneticists have found that drilling into the petrous bone — specifically targeting the cochlea and surrounding regions — and extracting the bone powder for DNA analysis yields successful ancient genome recovery in cases where no other bone in the body has preserved any usable material.

The petrous bone has become the primary target for ancient DNA extraction in studies of skeletal remains more than a few thousand years old.