The scientific hypotheses of Charles Darwin and Alfred Russel Wallace regarding natural selection and evolution were presented to the Linnean Society of London in 1858. Darwin's "On the Origin of Species", based on twenty years of work, was published a year afterwards. It formed the foundation of a scientific worldview in which the diversity of organismal morphology and function could be explained in terms of material causes. The science of biology was never the same after its publication. The revolution that it ushered changed how we view nature and the place of humanity in it.
Photo: The evolution of whales from terrestrial mammals is a powerful example of how new species have evolved. Blue whale (Lucia Di Iorio).
Graphics are reproduced with permission from John van Wyhe ed., The complete Work of Charles Darwin Online.