The 10,000-Year-Old Man Found In A British Cave — And The DNA Test That Changed What Scientists Thought Early Europeans Looked Like

It forms the bony covering of the inner ear structures — the cochlea and semicircular canals — and is one of the densest bones in the human body.

Its density is so extreme that it was once described as “rock-like” (the name derives from the Latin “petra,” meaning rock or stone).

This density matters for DNA preservation because it limits the penetration of water, microbial activity, and other agents of decomposition that destroy DNA in less dense bone.

The same density that makes the petrous bone difficult to cut also makes it an outstanding preserve of the genetic material it contains.

The identification of the petrous bone as the best source of ancient DNA was made primarily by Pontus Skoglund and colleagues in a 2014 paper in Philosophical Transactions of the Royal Society B, which analyzed DNA yield from different skeletal elements.