Harvesting cereals at Tappeh Sang-e Chakhmaq and the introduction of farming in Northeastern Iran during the Neolithic

Tappeh Sang-e Chakhmaq is the only Neolithic site in Northeastern Iran, characterised by aceramic and ceramic levels corresponding to an occupation of 1500 years from the eighth to the end of the sixth millennium BCE. The Western and Eastern Mounds represent the oldest and longest occupation among the sites identified East of the Zagros, providing a unique context to explore the origin and spread of farming outside the core area of the Eastern Fertile Crescent. We present data about the first harvesting activities in the Northeastern Iranian Central Plateau by applying usewear and microtexture analysis through confocal microscopy on sickle gloss blades. Our results indicate a community of pioneer farmers who settled down in the area carrying with them both domestic cereals as well as advanced techniques of cereal cultivation. We demonstrate that most of the tools were used for harvesting cereals in a fully ripened state collected near the ground, indicating a well-established cereal cultivation strategy. The use of straight shafts with parallel inserts in Tappeh Sang-e Chakhmaq, as known in some sites in the Zagros, suggests the dispersal of farming practices and technologies from the Eastern Fertile Crescent north-eastward across Iran. We observe an evolution in the degree of ripeness of harvested cereals along the first four levels of occupation of the Western Mound, where semi-ripe harvesting is relatively important, suggesting that domestic cereals to be harvested before full maturity were introduced into the village. From the topmost of the Western Mound and along the occupation of the Eastern Mound, ripe harvesting is dominant, showing a well-established cultivation strategy of fully mature cereal. This shift could indicate an in-situ evolution towards a better-established agricultural technology, including harvesting riper crops, that would have resulted in higher yields, as cereals were collected when the grain was fully formed.