Darwin's conversion: the Beagle voyage and its aftermath.

The issue o f how and when Charles Darwin became an evolutionist has long fascinated his biographers. Such historical curiosity is hardly surprising; for, without his own conversion, the orthodox young Darwin who once intended to become a clergyman would never have gone on to inspire the scientific revolution that now bears his name. Intimately associated with Darwin's conversion is the story of his circumnavigation of the globe as ship's naturalist aboard H.M.S. Beagle (1831-1836). Indeed, the voyage of the Beagle displays all the hallmarks of a heroic tale in the history of science. Young Darwin, a recent Cambridge University graduate and the third person to be offered the position as ship's naturalist, realized the scientific opportunity of a lifetime when he accompanied the Beagle around the world. "The voyage of the Beagle," Darwin asserted in his Autobiography, "has been by far the most important event in my life and has determined my whole career . . . . I have always felt that I owe to the voyage the first real training or education of my mind" (195811876] :76-77). For the nearly five years that Darwin was aboard the Beagle, he examined many little-explored regions and collected materials for what subsequently became nine volumes on the geology and natural history of the places he visited. Further inspired by his Beagle observations and collections, Darwin commenced within ten months of his return to England the first o f a series o f notebooks on the transmutation o f species, a subject on which he never ceased to reflect. Precisely what scientific ideas Darwin developed during the Beagle