Professor Richard Cornall tells us about his research on autoimmunity. Autoimmunity occurs when the immune system, which is normally designed to attack pathogens, ends up attacking the body. This can lead to a number of diseases such as diabetes and rheumatoid arthritis. Professor Richard Cornall aims to understand the causes of autoimmune disease, and also how people differ in their inherited susceptibility, and why these differences are sustained in human populations by natural selection.