08/2026 Isotope study reveals new insights into the earliest stages of cereal domestication in the Levant

A new paper published this week in PNAS by Cheryl Makarewicz, Pascal Flohr, and colleagues from the University of Oxford challenges the long-held view that increases in cereal grain size at the beginning of agriculture resulted primarily from genetic selection associated with cultivation. Instead, the researchers argue that larger grains initially emerged because cereal plants exhibited developmental plasticity in response to favourable growing conditions. The team employed a multidisciplinary approach that integrated grain morphology, weed ecology, and stable carbon isotope analyses of charred barley and emmer wheat recovered from the Pre-Pottery Neolithic sites of el-Hemmeh and Sharara (Jordan). Their findings indicate that phenotypic plasticity was a major factor influencing cereal evolution during the earliest stages of agriculture, preceding the development of fully domesticated crops.