When you think about the people who have made a lasting mark on our understanding of medical science, you probably think about celebrated scientific heroes like Jonas Salk, Thomas Hunt Morgan, Linus Pauling, Watson and Crick. I would like to encourage you to reserve a special place in that list for a poor tobacco farmer from Virginia named Henrietta Lacks. Mrs Lacks was being treated for cervical cancer at Johns Hopkins when samples of her tumor and normal cells were removed from her body without her consent. Those cell lines, which have important biological properties that allow them to be kept alive and replicated, have been propagated down to the present day, and have played an instrumental part in many medical breakthroughs of the past six decades — including the discovery of the Polio vaccine by Jonas Salk.