Ancient Genome of Broomcorn Millet from Northwest China in Seventh Century CE: Shedding New Light to Its Origin and Dispersal Patterns

Abstract

Broomcorn millet (Panicum miliaceum) is among the earliest domesticated staple crops in the world’s agricultural history and facilitated the development of several early agrarian cultures, particularly those originating in northern China. However, the propagation route of broomcorn millet in China from the Middle Ages to the present remains unclear. The aim of this study is to explore the genetic affinity between ancient and modern millet samples, trace the genetic origins and diffusion pathways of broomcorn millet, and provide insights into its domestication and spread. To achieve this, we sequence ancient DNA from broomcorn millet remains excavated from the Chashan Village cemetery (AD 691) in Gansu Province, China. Phylogenetic and population genetic analyses, integrating ancient and modern millet genomes, reveal a close genetic relationship between ancient millet and contemporary millet from Ningxia Province (445 km away from Chashan Village), suggesting a potential origin for the Chashan millet. This finding aligns with the tomb’s epitaph, which documents the reburial of the tomb’s owner, who was originally buried in Ningxia, and provides important archaeological evidence for understanding the interaction between geopolitical dynamics and the natural environment in northwest China during the late seventh century. Furthermore, outgroup-f3 and D statistics evidence suggests substantial genetic interactions between ancient millet and modern varieties from the Loess Plateau, Huang-Huai-Hai Plain, and Northeast Plain, indicating the dispersal route of broomcorn millet, along with human migration routes, from the northwest to northern China and ultimately to the northeast region, starting from the Middle Ages onward. This study enhances our understanding of millet’s genetic history, offers a novel perspective on burial archaeology, and provides valuable insights into the origins, domestication, and diffusion of broomcorn millet.