C. difficile diarrhea is largely a nosocomial disease and is the most frequent cause of diarrhea in hospitalized patients. Its occurrence in the outpatient setting, other than in patients confined to nursing homes, is much less common.
Darwin had arrived at a complete theory of evolution by 1839, but it was to be another 20 years before he published his ideas of evolution through natural selection in his epochal book On the Origin of Species by Means of Natural Selection.
Charles Darwin was a British naturalist who proposed the theory of biological evolution by natural selection. Darwin defined evolution as descent with modification, the idea that species change over time, give rise to new species, and share a common ancestor.