The archaeological record of these populations is extensive in terms of material culture — stone tools, bone tools, the residues of fires and camps, evidence of the animals hunted and the resources exploited.

But it is extraordinarily thin in terms of human physical remains.

The preservation problem is the central issue.

The freeze-thaw cycles that characterize Arctic soils are among the most destructive forces acting on buried biological materials.

Every winter, when the ground freezes, water in the pores of the sediment expands as it forms ice.

Every spring, when the ground thaws, that ice melts and contracts.

This repeated expansion and contraction physically disrupts the sediment structure and subjects any rigid objects buried within it — including bone — to repeated mechanical stress.