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

When water freezes in the pores of soil and sediment, it expands; when it thaws, it contracts.

This repeated expansion and contraction works on any rigid object buried in the sediment — including bone — creating stress that cracks and fractures the material over time.

Permafrost, the permanently frozen ground that underlies much of the Arctic, can preserve organic material extraordinarily well, but only when it remains genuinely frozen; the permafrost margins and the seasonally active surface layer are far less favorable.

The result is that human skeletal material from the early periods of Alaskan and Beringian prehistory is extraordinarily rare.