First, it’s important to understand what permafrost is. Permafrost should not be thought of as a large chunk of ice that stays frozen for long periods of time. In fact, it is not defined by the presence of ice at all! Instead, it is defined by temperature. Permafrost is a sediment layer that remains frozen for more than two consecutive years. It is made up of sand, silt, gravel, and/or soil which may be bound together by ice. This means it’s possible for some layers of permafrost to have no ice whatsoever.

Shallow permafrost may thaw over time, whereas deep and thick permafrost layers have remained frozen for several hundred thousand years.

When permafrost does thaw, the warmth and moisture from melting snow or ice nearby mean animal remains released from the permafrost will begin to decompose.

While keratin, the protein found in hair, is insoluble in water (meaning water alone will not degrade keratin), there are bacteria and fungi that will feed on the protein, causing it to break down. Wet, and often warm, environments are necessary for bacterial and fungal growth. Think about the sinkhole at The Mammoth Site. When it still had water, that water was very warm. That heat and moisture were the perfect conditions for the organisms that feed on keratin. As a result, we do not find hair preserved at The Mammoth Site.