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By transforming a primitively hostile environment into a survival aid according to its needs, humanity, through civilization, has largely freed itself from the forces of natural selection. On a deeper level, the selection of social instincts, in itself conducive to the growth of rational capacities, has favored community-based organization, cooperation, the generalization of solidary behaviors, the intensification of affective feelings, as well as the progressive extension of sympathy, morality, law, protection of the weak, and recognition of the other as a fellow human being. Fulfilling the duty—imposed by the first revolution introduced into the science of living things by On the Origin of Species—to clearly situate the human species within the animal series, The Descent of Man and Selection in Relation to Sex simultaneously accomplishes, in 1871, the obligation to define the mechanism by which it undergoes its passage into civilization: through the path of social instincts, natural selection selects civilization, which opposes natural selection. This reverse effect of evolution, expressed by Patrick Tort through the topological metaphor of the Möbius strip, today enables us to consider the second revolution brought about by Darwin as an anthropologist as a reversal without rupture, finally allowing for a non-reductionist understanding of the relations between the natural and social sciences.