In the industrial age, the demographic question is influenced by Malthus’ population principle, which links the demographic concern with the upholding of social inequalities. With the Malthus-Darwin-Galton association, this concern took on a eugenicist dimension. This is concretely visible in world society. Negative eugenics (forced sterilization) makes it possible to limit births among poor populations in the South. At the same time, positive eugenics, driven by biotechnology, is developing in the rich countries. How can we take into account the natural limits to the expansion of the world’s population, without encouraging the spread of eugenics?