Contrasting diachronic regional trends in cereal grain evolution across Eurasia: a metadata analysis of linear morphometrics from the ninth millennium BCE to today Rita Dal Martello 1,2 , Yiming V. Wang 3,4 , Basira Mir Makhamad 2 , Robert N. Spengler 2 and Dorian Q Fuller 5,6 1 Asian and North African Studies Department, Ca' Foscari University of Venice, Venezia, Italy 2 Domestication and Anthropogenic Evolution Research Group, and 3 Anthropogenic Ecology Research Group, Max Planck Institute of Geoanthropology, Jena, Thüringen, Germany 4 Institute of Geosciences, Friedrich-Schiller-Universitat Jena, Jena, Thüringen, Germany 5 Institute of Archaeology, UCL, London, UK 6 School of Cultural Heritage, Northwest University, Xi'an, Shaanxi, People’s Republic of China RDM, 0000-0001-8367-1309; YVW, 0000-0003-3228-5592; BMM, 0000-0002-1414-0392; RNS, 0000-0002-5648-6930; DQF, 0000-0002-4859-080X The domestication of grain crops is among the most important phenomena to facilitate humanity’s cultural development, and seed size increases are taken as one of the earliest domestication traits. Much remains unknown about the ecological drivers and cultural mechanisms surrounding this trait, but morphometric analyses have been crucial to investigate the topic for decades. Measurements on ancient cereal grains show that they evolved to produce larger seeds in their region of origin prior to dispersing beyond their progenitor range. This paper takes a transcontinental (Europe and Asia), long-term approach to comparative morphometric data. Unpublished measurements from over 10 sites of barley, free-threshing wheat, broomcorn millet, and foxtail millet from Central Asia and China have been collected for this study. We have contrasted these with published data from Europe, southwest and Central, East and South Asia. We investigate whether these cereals evolved in parallel or divergent ways across different lineages after they dispersed from their centres of origin; we trace seed size changes from initial cultivation through their spread and eventual adaptation to novel environments. This comparative analysis allows us to discuss rates of evolution and highlight evolutionary trends within some of the most important cereal crops across the Eurasian continent. This article is part of the theme issue ‘Unravelling domestication: multi-disciplinary perspectives on human and non-human relationships in the past, present and future’. 1. Introduction The domestication of plants and animals allowed for the food surplus that spawned population expansions across the globe—the agricultural demo- graphic transition; these domesticated crops facilitated the formation of denser conglomerations of populations, leading to urbanism and eventually, the formation of social hierarchies and societies segmented into specialized production groups [1,2]. In this way, domestication is the most important © 2025 The Author(s). Published by the Royal Society. All rights reserved. Research Cite this article: Dal Martello R, Wang YV, Mir Makhamad B, Spengler RN, Fuller DQ. 2025 Contrasting diachronic regional trends in cereal grain evolution across Eurasia: a metadata analysis of linear morphometrics from the ninth millennium BCE to today. Phil. Trans. R. Soc. B 380: 20240193. https://doi.org/10.1098/rstb.2024.0193 Received: 29 June 2024 Accepted: 2 December 2024 One contribution of 17 to a theme issue ‘Unravelling domestication: multi-disciplinary perspectives on human and non-human relationships in the past, present and future’. Subject Areas: plant science Keywords: evolution, domestication, morphometrics, barley, wheat, millet Author for correspondence: Rita Dal Martello e-mail: rita.dalmartello@unive.it Electronic supplementary material is available online at https://doi.org/10.6084/ m9.figshare.c.7749662. Downloaded from https://royalsocietypublishing.org/ on 15 May 2025