The effectiveness of Neolithic sickles in the Middle East: an experimental approach

In the Near East "sickles" or "glossy pieces" occur for the first time during the Natufian period. These tools are either "sickle blades" or "sickle elements". "Sickle blades" are used hafted or hand-held as single cutting tools. "Sickle elements" are inserted in a haft in order to create a composite instrument. When sickles are made from flint, they are easily recognized since they usually bear a macroscopic gloss that covers a wide area on both sides of the tool. Experimental and microscopic studies have shown that the majority of these tools were used as sickles to harvest cereals or, less frequently, soft siliceous plants such as reeds and typha. Macroscopic glosses of different natures develop on various occasions, for example: on elements mounted on threshing sledges; when limestone is worked with the addition of water; when humid clay is scraped; etc. When sickle elements are made from obsidian, no macroscopic gloss develops and use wear is rarely observed with the naked eye. In this case, the worn area on the tool presents a mat aspect and abrasion features. Such tools are rarely recognized as such. Sometimes, abrasion features are erroneously interpreted as harvesting marks. The frequency of harvesting instruments increased during the Neolithic period. According to several analysts, the use of sickles to harvest cereals was preferred to other harvesting techniques such as uprooting, the use of beaters and baskets, and mesoarias in order to maximize yields. Moreover, the evolution of the morphology of sickles has often been related to the gradual adoption and the spread of agriculture. Sickles found on archaeological sites may be complete or broken. The hafts were made from wood, antler, or horn and the sickle elements were inserted parallel or oblique to the haft and often glued with bitumen. If only sickle elements are discovered on the site, the distribution of the gloss and the bitumen and the size of the blanks provide information on the mode of hafting, the degree of curvature of the haft, and, in some cases, the number of lithic inserts. The aim of the present paper is to examine the relation between the morphology and efficiency of the sickles and the adoption of agriculture by the Neolithic communities in the Near East. Based on publications, we identify three major steps in the evolution of sickle manufacturing in this region: the appearance of composite sickles, increased curvature of the hafts, and the adoption of oblique inserts. An experimental programme was devised in order to evaluate the impact of the following factors on sickle productivity: the harvester; the curvature of the haft; the length of the cutting edge of the lithic blade; the position of the blade in relation to the haft (parallel or oblique); the raw material used (flint or obsidian). Statistical analysis of the results allows the impact of each factor and of combinations of factors to be evaluated. Our research has shown that the harvester parameter is important. The knowledge, skill, and physical strength of the harvester as well as his/her adaptation to the use of different tools and to different working conditions influence productivity. These factors affect the movement executed by the harvester, the distribution of use wear on the tool, and the degree of damage on the cutting edge. Our results also stress the impact of the lithic tool's raw material on sickle efficiency. As a result of its mechanical properties, flint is better adapted to harvesting than obsidian. In particular, flint is less brittle and less prone to abrasion than obsidian. We examine the distinct behaviour of the two raw materials, when they are subject to similar constraints, through macroscopic and microscopic analysis of the damage on the experimental tools. Considering the interaction between the morphology of the haft and the position of the inserts, our data confirm that the use of a curved haft with obliquely set inserts increases the cutting capacity of the sickle. The curvature of the haft and the length of the cutting edge determine the number of strokes needed to harvest a given field area. When archaeological data are examined, published information on sickle morphology concerns mainly the Natufian in the southern Levant and the PPNA and PPNB in northern Syria. The scarcity of obsidian sickle elements can be related to the difficulty of identifying characteristic use wear but also to the choice of flint for its mechanical properties and the uneven geographical distribution of obsidian. Large quantities of obsidian sickle blades are found in archaeological sites located near obsidian sources, for example, Asikli Hoyuk in Cappadocia, Turkey. Three stages are identified in the evolution of Near Eastern sickles between 12000 and 7000 B.C. During the Natufian period, the adoption of composite instruments had an influence on the efficiency of the sickles. During the PPNB, the gradual increase of haft curvature probably played a role in the harvester's tempo and movements. In the latest phase of the PPNB, the practice of agriculture was widespread and composite sickles with a curved haft and oblique inserts are common. We argue that this choice can be partly explained by the need for sickle efficiency. Changes in the system of lithic production and the organization of agricultural activities during the same period also influence the adoption of oblique inserts. Moreover, comparisons between the evolution of sickles in different geographical areas, northern Syria and Cyprus, indicate that technical traditions, technical transfer and societal context were more critical in the choice of sickle morphology.