Microremains on grinding tools as source of information about past lifestyles

In Stone Age sites, evidence of exploitation of plant resources is rare because plant remains are easily perishable. The study of starch grains and phytoliths, trapped on the surface of grindstones and pestle-grinders, recently added new information on this topic, evidencing the production of flour from numerous wild plants including wild cereals – more exactly oats –over 30,000 years ago. Indeed, the occurrence of plant remains on the lithic surfaces of grinding tools not only indicates the plants used for feeding purposes, but also highlights the ability to manipulate food. The plant remain analysis includes several steps: sampling, starch grains analysis and identification of the plants. With the aim to collect more information, different sampling procedures were tested. The recovery of starch grains on stone tools is in itself an important information as it demonstrates the use of the tool for obtaining flour and therefore for food purposes. Throughout the world, flour represents one of the main sources of carbohydrates in the human diet. The identification of starch grains shows that both underground storage organs and aerial portions of the plant, such as caryopses, were ground. The use of selected plant organs is tightly linked with the characteristics of the environment where the people lived: the underground storage organs of Typha were widely used as a food source in wet areas, while in dryer areas the use of caryopses seems to prevail. Therefore, this kind of research may improve our knowledge about lifestyle, activities and dietary habits of ancient populations and, ultimately, their past culture.