This paper traces the ethical consequences implicit in the collapse of the animal/human boundary. This boundary became suspect as early as the mid-17th century, but it was Darwinian evolution that gave the lethal blow to the distinction. There are two aspects in which the concept of evolution by natural selection gained ethical relevance: the one is the evolution of ethics, the other is the ethics of evolution. Although Darwin himself was engaged mostly in the former, his social scientist followers, such as Herbert Spencer, elaborated on the latter. However, whereas the Social Darwinists pretended to justify values on a scientific basis, their theories were based on the uncritical identification of their pre-existent value choices with the “ways of nature.” After the resurgence of biological inquiries into morality following World War II, leading sociobiologist E. O. Wilson claimed that the biologization of ethics is unavoidable. However, his results were self-contradictory that further left the main focus of ethics untouched and were prone to fall back into Social Darwinism. Environmental ethicists also capitalize on the Darwinian notion of the evolution of ethics. While their effort to use evolution as a justification for particular moral practices is still questionable, their interpretation of living structures as adapted normative systems is far more promising. The critical examination of the fact/value dichotomy in relation to moral as well as amoral living systems is crucial in a biologically sensitive moral philosophy that wants to avoid the pitfalls of its predecessors.