On a December night in 1831, HMS Beagle, on a mission to chart the coast of South America, sailed from Plymouth, England, straight into the 21st century. Onboard was a 22-year-old amateur naturalist, Charles Darwin, the son of a prosperous country doctor, who was recruited for the voyage largely to provide company for the Beagle's aloof and moody captain, Robert FitzRoy. For the next five years, the little ship — just 90 feet long and eight yards wide — sailed up and down Argentina, through the treacherous Strait of Magellan and into the Pacific, before returning home by way of...