In choosing Barry Marshall and Robin Warren as winners of the 2005 prize in physiology or medicine, the Nobel awards committee has turned away from basic research this year and plumped instead for old fashioned medical detective work.

Professor Marshall, 54, and Dr Warren, 68, are cited for their 1982 discovery of “the bacterium Helicobacter pylori and its role in gastritis and peptic ulcer disease.” What the brevity of that citation conceals is the extent to which their work opened the …