Sickle cell disease only occurs when both parents contribute the trait, and mostly in those of African descent. Where did it come from? How did it evolve? Tony Allison, a molecular biologist, noticed a connection between sickle cell and immunity against malaria when he was working in East Africa in the 1950s. Follow his story on natural selection and evolution with this note-worthy film. Accompany it with your choice of lessons or activities provided by the publisher.