Chronic ill health plagued Charles Darwin for most of his adult life. Bouts of nausea, insomnia, chest pain, skin problems, dizziness, abdominal stress, vomiting, palpitations, and flatulence eventually transformed an adventurous young world traveler into a housebound recluse. Many people, including Darwin himself, have speculated about the nature of his illness. Some medical historians have suggested that he picked up a tropical disease during his epic voyage aboard the Beagle. While the debate may never be resolved, two medical researchers from the University of Iowa believe they’ve come up with the best diagnosis yet of Darwin’s condition. The great naturalist, they say, may have suffered from panic disorder.