In this chapter we examine how, during the second part of the nineteenth century and the beginning of the twentieth century, assumptions about the origins of life were specifically linked to the development of theories of evolution and how these conceptions influenced assumptions about the possibility of life on other planets. First we present the theories of the origins of life of Charles Darwin (1809–1882) and Herbert Spencer (1820–1903) and underline how they were linked to the knowledge of physical and chemical conditions of environments. These two examples lead us to think about the relationship between the origin of life, evolutionary biology, and geology, particularly the uniformitarian principle. An important point is the extension of the comprehension of terrestrial conditions of emergence and evolution of life to other planets. We claim that there was a sort of extended uniformitarian principle, based not only on time, but also on space. Second, after a brief look at panspermia theory, we compare two examples of assumptions about life on other planets. The French astronomer Camille Flammarion (1842–1925) and the French biologist Edmond Perrier (1844–1921) presented views that consisted in complex analogies between life on Earth and life on other planets. We analyze how they used neo-Lamarckian biological concepts to imagine living beings in other worlds. Each planet is characterized by a particular stage of biological evolution that they deduce from the state of living beings on Earth. The two scientists explained these different states with neo-Lamarckian principles, which were based on environmental constraints on organisms. Therefore these descriptions presented a sort of history of life, including the past and the future. We claim that their assumptions could be some intellectual exercises testing neo-Lamarckian theories. Moreover the description of human beings on other planets, and particularly the Martian epianthropus presented by Perrier, were complex utopias, which finally spoke about us and about an ideal future.
- Nineteenth Century
- Spontaneous Generation
- Ideal Government
- Epistemological Obstacle
- Important Common Characteristic
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