Bioarchaeological evidence for commensal brown rats (Rattus norvegicus) in early Neolithic China

Due to its commensal relationship with humans, facilitating its dispersal from its natural range in East Asia, the brown rat (Rattus norvegicus) is now one of the most cosmopolitan and invasive mammals. Brown rats are also vectors of human pathogens and the most commonly used mammalian model (after mice) for biomedical research. Despite their major role in biodiversity loss and medicine, our understanding of a likely origin for their commensal relationship with humans in China still relies on modern population genetics, without a reliable timeframe of localisation. In this research, we have tried to fill this gap using direct information from the archaeological remains of rats collected by Chinese colleagues in several archaeological sites dated between 9000 and 3500 BP. Thanks to high-resolution morphometrics and direct 14C dating, we have identified the occurrence of the brown rat (Rattus norvegicus) within the domestic area deposits of the early Neolithic site of Jiahu by 7500 cal BP, suggesting a tentative link between rice agriculture and an early commensal behaviour of this species.