Wells was more concerned with secular social theories at the time rather than religion. One of the major social theories of the late 19th-century adapted Charles Darwin's theories on evolution to justify 19th-century social stratification between the rich and poor. In "Origin of the Species," Darwin argued that different environments encouraged the reproduction of those species whose varying traits best suited them to survive; their offspring, in turn, would be better adapted for the new environment, as would their offspring, and so on. Social Darwinism frequently abused this concept of "natural selection." Evolution does not lead to the "perfectibility" of any species, as is generally perceived, but to the increasing adaptability and complexity of a species. Social Darwinism ignored this idea and contended that the social environment was much like the cutthroat natural environment, and that those who succeeded were biologically destined to do so and to continue in their march to human perfection. On the flip side, those who failed had inferior traits and deserved to do so.