Social degeneration was a widely influential concept at the interface of the social and biological sciences in the 18th and 19th centuries. During the 18th century, scientific thinkers including George Louis Leclerc, comte de Buffon, Johann Friedrich Blumenbach, and Immanuel Kant posited that humans shared a common origin but had degenerated over time due to differences in climate. This theory provided an explanation of where humans came from and why some people appeared different from others. In contrast, degenerationists in the 19th century feared that civilization might be in decline and that the causes of decline lay in biological change. These ideas derived from pre-scientific concepts of heredity ("hereditary taint") with Lamarckian emphasis on biological development through purpose and habit. Degeneration concepts were often associated with authoritarian political attitudes, including militarism and scientific racism, and a preoccupation with eugenics. The theory originated in racial concepts of ethnicity, recorded in the writings of such medical scientists as Johann Blumenbach and Robert Knox. From the 1850s, it became influential in psychiatry through the writings of Bénédict Morel, and in criminology with Cesare Lombroso. By the 1890s, in the work of Max Nordau and others, degeneration became a more general concept in social criticism. It also fed into the ideology of ethnic nationalism, attracting, among others, Maurice Barrès, Charles Maurras and the "Action Française". Alexis Carrel, a French Nobel Laureate in Medicine, cited national degeneration as a rationale for a eugenics programme in collaborationist Vichy France.