The presence of starch grains on prehistoric stone tools from the humid neotropics: Indications of early tuber use and agriculture in Panama

One of the greatest challenges faced by Neotropical archaeobotanists is to document the origins and history of crops like manioc (Manihot esculenta Crantz), yams (Dioscorea spp.) and sweet potato (Ipomoea batatas), which were grown for their starch-rich underground organs. The records left by early Europeans make it clear that such plants provided a staple food source for numerous indigenous populations in southern Central America and South America (Sauer, 1950). However, the history of these and other tuber crops is very poorly understood because they generally do not leave fossilized remains that can be recovered in archaeological sediments. Starch grain analysis has the potential to help in our understanding of tropical plant domestication. Starch grains, microscopic granules within the plant where the plant's energy is stored, are produced in abundant numbers and varied morphological forms in tuberous and other crop plants, such as maize and beans. Starch grains indistinguishable in morphology and size from modern varieties of Manihot esculenta, Dioscorea spp., Zea mays, and Maranta arundinacea have been isolated from the surfaces of stone tools from archaeological sites in the lowland Central American tropics that date to the last 8000 radiocarbon years. Starch grains also provide important data about the functions of stone grinding tools recovered from early archaeological sites in the humid and lowland Neotropics. © 1998 Academic Press.