LAUSR

Significance Early scientific investigations of the Neolithic Near East, such as the excavations of Ali Kosh and Chagha Sefid during the 1960s, were pioneering for their time. Modern, critical reexaminations of these (and other) sites have led to substantially different interpretations. New insights with respect to fauna, flora, and chronology have overturned widely held ideas about the emergence of food production. Chemically determining the geological origins of all lithic artifacts made from obsidian has hitherto been overlooked. The observed accelerating diversity in these obsidian assemblages indicates intensifying connections among Neolithic sites, highlighting intercommunity contacts as a mechanism for social change as populations grew during a demographic transition purported to have occurred within food-producing societies worldwide, from western Europe to Mesoamerica.