Neolithic hydroclimatic change and water resources exploitation in the Fertile Crescent.

In the first millennia of the Holocene, human communities in the Fertile Crescent experienced drastic cultural and technological transformations that modified social and human-environments interactions, ultimately leading to the rise of complex societies. The potential influence of climate on this "Neolithic Revolution" has long been debated. Here we present a speleothem record from the Kurdistan Region of Iraq, covering from Early Neolithic to Early Chalcolithic periods (~ 11 to 7.3 ka, 9000-5300 BCE). The record reveals the influence of the Siberian High on regional precipitation, and shows large hydroclimatic variability at the multicentennial scale. In particular, it highlights wetter conditions between 9.7 and 9.0 ka, followed by an abrupt reduction of precipitation between 9.0 and 8.5 ka, and a wetter interval between 8.5 and 8.0 ka. A comparison with regional and local archaeological data demonstrates an influence of recorded hydroclimatic changes on settlement patterns (size, distribution, permanent vs. seasonal occupation) and on the exploitation of water resources by Neolithic to Chalcolithic populations. Our record does not show prominent hydroclimatic changes at 9.3 and 8.2 ka, thus not supporting direct influence of such rapid and widespread events on the process of Neolithization and its cultural dispersal.