The effects of cooking on avian eggshell microstructure

Although avian eggshell is a common component of the faunal assemblages at archeological sites, attempts to identify it taxonomically and use it to construct complex economic arguments have been limited. One method of identifying avian eggshell, using a scanning electron microscope (SEM) to examine characteristic microstructures, can provide more specific taxonomic identifications. This study sought to test whether cross-culturally common egg preparation methods were likely to damage eggshell in ways that would make it difficult to identify taxonomically under a SEM. We found that most food preparation practices caused minimal or no damage. Only cooking eggs in hot coals caused significant damage to eggshell microstructures, making it impossible to identify these eggshells taxonomically. With the exception of fire-cooked eggs, the lack of damage to eggshell microstructures meant that SEM analysis was sufficient to identify cooked eggshells taxonomically but insufficient to differentiate most cooking techniques.