What is preservation bias?

Loss of Perishable Commodities: Evidence for many aspects of daily life and trade, including slaves, wine, clothing, and wooden tools, is rarely recorded archaeologically because these materials perish easily.

The Role of Special Conditions: Fragile organic remains typically only survive in rare, special environmental conditions, such as being waterlogged, charred, frozen, or desiccated (dried out). For example, plant seeds are frequently found only if they were burned during cooking, a process that helps preserve them from natural decay.

Impact on Interpretation: Because of this bias, archaeologists are often working with only a fraction of the original evidence. Interpreting the past requires acknowledging these gaps to avoid "privileging" the durable materials found in the record over the perishable ones that have been lost.