My current research deals with mycobacterial pathogens such as tuberculosis and leprosy. In particular, I am interested in the origin and spread of these diseases in antiquity and their interaction with past human and animal populations. Information from archaeological contexts can often provide valuable information which can test and refine phylogenetic models for mycobacterial evolution. In the case of leprosy we can recover information from geographical locations where the disease is no longer found. Recent projects have focused upon characterizing the strains of M.leprae behind the rise in medieval leprosy in Britain and Europe and reasons for its decline. Currently, I have begun to study medieval isolates of tuberculosis in the hope of learning something of the other mycobacterium which was probably at least partly responsible for the decline in leprosy in Europe.