Some 2,000 years ago, certain unfortunate individuals were violently killed and buried not in graves but in bogs. What was a tragedy for the victims has proved an archaeologist's dream, for the peculiar and acidic properties of the bog have preserved the bodies so that their skin, hair, soft tissue, and internal organs--even their brains--survive. Most of these ancient swamp victims have been discovered in regions with large areas of raised bog: Ireland,...