Above those layers come later occupations by modern humans.

For Shanidar Z, the specific conditions of preservation were both helpful and damaging.

The sediment protected the remains from carnivore disturbance.

But the weight of sediment accumulating over tens of thousands of years — combined, possibly, with freeze-thaw cycles affecting the cave deposits — compressed and shattered the skull.

The result was that the skeleton survived but the skull arrived at the Cambridge laboratory in pieces: more than two hundred fragments, some no larger than a fingertip, embedded in a block of consolidated sediment.

What the team did with that block — the excavation under microscopes, the digital scanning, the 3D reconstruction — is what transformed a fragmentary relic into a face.