Identification of maize in absorbed organic residues: a cautionary tale

Starchy grains are an essential part of human diet in most agricultural groups, and are attributed an important role in the development of complex societies. Maize is a starchy grain domesticated in Mesoamerica that was an important foodstuff throughout the Americas before Contact, and around the world afterwards. An experimental study of the degradation of maize lipids suggests that the unsaturated fatty acids comprising the majority of maize lipids degrade rapidly, producing a virtually unidentifiable organic residue after 3 months deposition. Compounds in maize lipids decompose variably, depending upon depositional environment, making calibration of organic residue degradation impracticable. Variable decomposition of components of absorbed organic residues makes a wider range of improved experimental studies important, and suggests that identifying maize, and by implication starchy grains, from chemical analysis of absorbed organic residues requires a wider range of approaches than those previously attempted.