The survival of any organic material from 13,000 years ago is never guaranteed, and the fact that the Anzick child’s bones survived in analyzable condition — including, crucially, with enough preserved DNA for genome sequencing — required a specific set of fortunate circumstances.

Bone preservation over geological time depends on a complex interplay of environmental factors.

Bones are primarily made of hydroxyapatite (a calcium phosphate mineral) and collagen (a protein).

The mineral component is more resistant to degradation than the organic component, but both can be destroyed by acidic soil conditions, by microbial activity, by physical disruption, and by various chemical processes that alter the bone’s structure.

The Anzick burial’s location in a sandstone matrix helped preservation in several ways.