This year’s Nobel Prize in medicine or physiology was announced this morning. Barry Marshall and J. Robin Warren won for discovering that ulcers can be caused not by stress or genes but by a bacterium called Helicobacter pylori (shown here). As my fellow Corantean, Derek Lowe, observes, this story follows the classic arc from, "You’re completely bonkers" to "You’re going to Stockholm." But it also illustrates a point that I made when last year’s Nobelists were announced: it demonstrates how intimately woven evolutionary biology is becoming with medicine.

It turns out that Helicobacter infects half of all people on Earth. Once Marshall and Warren showed that this bug caused ulcers (as well as certain cancers and other