Seeing red: The use of a biological stain to identify cooked and processed/damaged starch grains in archaeological residues

Abstract

Starchy plant foods are a major component in the diet of almost all peoples, particularly hunter-gatherers such as Aboriginal Australians. However, the archaeological preservation of such plants is rare, as is other direct evidence of plant use by past peoples. While analysis of starchy residues preserved on artefacts has gained acceptance as an effective method for identifying starchy plant use, it is very difficult using the standard morphological method to accurately identify starch grains that have been damaged by processing activities such as milling or cooking. Therefore, a method is presented for the identification of such damaged starch grains using the stain Congo Red, which dyes damaged (cooked or processed) but not undamaged starch. This method has been applied to identify cooking or milling activities in the subsistence of hunter-gatherers from south-east Queensland, Australia.