Starch is a highly accessible biological energy reserve and the second most ubiquitous polysaccharide after the structural form known as cellulose. Chemical reactions with these co-concurrent molecules must be taken into account when attempting to conceptualise diagenetic processes of starch granules in archaeological contexts. Commonly, starch granules do not exist in isolation they are admixed with non-starch polysaccharides, lipids, and proteins co-occurring in variable proportions, depending on the plant source.
When the cells decay, a few of the starch granules may be afforded physical protection through entanglement in the remnant cell wall matrix. The biosynthetic deposition of the crystalline starch granules occurs within plant organelles inside cells surrounded by lignocellulosic walls. Customarily, in archaeology, confirmation of starch chemistry uses polarised light microscopy of birefringent granules to display a distinctive “Maltese cross”. New taphonomic criteria and authenticationįresh starch granules are polysaccharide polymers with semi-crystalline and amorphous regions, exhibiting unmodified birefringence from a concentric arrangement of crystalline, helical amylopectin clusters. Since then, dozens of articles have appeared in the field of archaeology on the pervasive, but little understood, presence of starch recovered from tools, sediments, and recently, dental calculus ( Henry and Piperno 2008, 2011 Hardy et al. These studies focused mainly on sites from the Americas and Australasia, and established the extraction, detection, description, and identification methods currently in use.
During the ensuing decades, the pioneering combination of starch granule identification and studies of early human diets opened the door for an exponential growth of the field and publicity in high impact venues (e.g., Loy et al. This approach has persisted until today ( Czaja 1978 Jane et al. The authors attributed the exceptional preservation of starch to extreme aridity, and used granule morphology to infer source plant taxonomy, a practice with origins in late 19th and early 20th century biochemistry ( Nageli and Nageli 1858 Meyer 1895 Reichert 1913). Recovered granules from 4000-year-old desiccated tubers were identified as potato starch using optical and histological techniques. (1982) published the earliest account of archaeological starch granules from work at sites north of Lima (Peru) more than 35 years ago.
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