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However, in the 1920s Christian fundamentalists in the United States developed their literalist arguments against modernist theology into opposition to the teaching of evolution, with fears that Darwinism had led to German militarism and was a threat to religion and morality.
Since then, most criticisms and denials of evolution have come from religious groups, rather than from the scientific community.
Although many religious groups have found reconciliation of their beliefs with evolution, such as through theistic evolution, other religious groups continue to reject evolutionary explanations in favor of creationism, the belief that the universe and life were created by supernatural forces. S.-centered creation–evolution controversy has become a focal point of perceived conflict between religion and science.
Several branches of creationism, including creation science, neo-creationism, and intelligent design, argue that the idea of life being directly designed by a god or intelligence is at least as scientific as evolutionary theory, and should therefore be taught in public education.
The specific hereditary mechanism Darwin hypothesized of pangenesis that supported gradualism also lacked any supporting evidence and was disputed by the empirical tests of Francis Galton.
Although evolution was unchallenged, uncertainties about the mechanism in the eclipse of Darwinism persisted from the 1880s until the 1930s inclusion of Mendelian inheritance and the rise of the modern evolutionary synthesis.