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.

Ancient oral microbiomes support gradual Neolithic dietary shifts towards agriculture.

The human microbiome has recently become a valuable source of information about host life and health. To date little is known about how it may have evolved during key phases along our history, such as the Neolithic transition towards agriculture. Here, we shed light on the evolution experienced by the oral microbiome during this transition, comparing Palaeolithic hunter-gatherers with Neolithic and Copper Age farmers that populated a same restricted area in Italy. We integrate the analysis of 76 dental calculus oral microbiomes with the dietary information derived from the identification of embedded plant remains. We detect a stronger deviation from the hunter-gatherer microbiome composition in the last part of the Neolithic, while to a lesser extent in the early phases of the transition. Our findings demonstrate that the introduction of agriculture affected host microbiome, supporting the hypothesis of a gradual transition within the investigated populations.