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 argued 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 a