Understanding the evolution and epidemiology of RNA viruses in their natural hosts is essential for disease emergence prediction and control. Arenaviruses and hantaviruses are (mostly rodent-borne) RNA viruses causing hemorrhagic fevers and neurological disorders in humans. They are well studied in Europe and the Americas but understudied in Africa. However recent discoveries of new viruses suggest they are highly diverse in Africa. Based on previous data, it has been assumed that both groups of viruses have had long co-evolutionary histories with their hosts. However, this has not been adequately tested for African arenaviruses, and a recent study of hantaviruses instead suggests a very short co-history of preferential host switching, which has massive implications for viral emergence and control. Our project team, specialists in rodent ecology, evolution and virology, intends to fill the gap in scientific knowledge of these viruses in Africa by investigating their biodiversity, biogeography and evolutionary history in relation to their hosts.