Heated mud bricks in submerged and coastal Southern Levant Pre-Pottery Neolithic C and Late Pottery Neolithic/Early Chalcolithic settlements: Diachronic changes in technology and their social implications

Technological and social practices can be deciphered by deployment of multiple techniques that have been developed in the last years for the study of sun-dried and heated mud bricks. This research analyzed for the first time the chain of operational processes involved in the manufacture of heated mud bricks in the Neolithic of the Southern Levant. Heated mud bricks (and associated soil/sediment controls) were studied from four Neolithic sites in Israel; the submerged Pre-Pottery Neolithic C (PPNC) site of Atlit-Yam, the coastal PPNC site of Bene Beraq, the submerged late Pottery Neolithic/ Early Chalcolithic (PN/EC) site of Neve Yam and the coastal PN/EC site of 'Ein Asawir. In all sites, the bricks have been found in open areas within the settlements, in semi-circular concentrations of either pits or piles. The bricks have been characterized macroscopically (shape, size, color pattern) and a variety of micro-geoarchaeological techniques have been used to characterize the mud brick materials (and control soils/sediments) from the four sites. These included, Fourier Transform Infrared Spectroscopy (FTIR), Electrical Conductivity (EC), pH analysis, calcite content measurements, Loss on Ignition (LOI), phytolith analysis, and petrography. The results show that all bricks have been produced from sediments from the sites' vicinities. PPNC mud bricks are generally devoid of any type of temper and have been heated to a relatively wide range of high temperatures (600–900 °C) under heterogeneous atmospheric conditions. PN/EC mud bricks are enriched in calcite and include vegetal temper, and have been heated to a relatively narrow range of temperatures (500–700 °C) that is lower than that observed in PPNC mud bricks, and under standard oxidizing conditions. The grass component of temper in the PN/EC bricks may originate from emmer wheat, based on phytolith morphological analysis. Interestingly, FTIR criteria for heated clay minerals preserve underwater for millennia, and so do phytolith assemblages; these observations indicate that micro-geoarchaeological proxies can (and should) be utilized in studies of marine submerged prehistory. Overall, a diachronic perspective on the operational chain of PPNC and PN/EC mud bricks, from raw material procurement through tempering, moulding and firing is provided, which may be translated into developing pyrotechnological practices in light of increasing social complexity during the Neolithic. We propose that purposeful tempering by emmer wheat (agricultural by-products) may be related to socioeconomic factors such as symbolic addition of domestic surplus and that temper diversity in the PN/EC may also mirror sedentary life where domestic waste accumulated on local soil/sediment and thus incorporated into mud bricks. Furthermore, we propose that the more standardized pyrotechnological characteristics of PN/EC bricks are related to increased social control over this skill/craft.