Charles Darwin once said that going public with his theory of natural selection was like confessing to murder. Despite the common assumption that we live in a post-Darwinian world, the perennial resurgence of creationism serves as a reminder that Darwinian theory cannot be taken for granted as a shared understanding of the origin of humans and the mechanisms at work in the natural world. Yet the difficulties that attend embracing the theory of natural selection are not felt only by "fundamentalist" Christians or unenlightened persons. Misgivings and misunderstandings regarding evolutionary theory persist, I think, even among those who consider themselves supporters of the theory. The fact that Darwin likened evolution to murder suggests that even he was sometimes uneasy about the implications of the theory that would ultimately bear his name. Nevertheless, murder he did.
Today the theory of evolution plays a surprisingly small role in ethics, and this is all the more extraordinary when we consider how little impact it appears to have had in much of contemporary environmental ethics. The arguments that follow grew out of my perception that many ecological theologians have not dealt adequately with the implications of natural selection, despite the relevance of Darwin's theory for their enterprise. The incorporation of the theory of natural selection into environmental ethics is crucial for a number of reasons. In addition to his argument that species are adapted to their environment by means of this process, Darwin also established that species have descended from others, and that all species are related, in varying degrees, to one another. Historically, the recognition that animals and humans are kin gave a greater urgency to the question of how animals ought to be treated—whether animals share our mental, moral, and emotional capacities, whether they have similar "rights," and so on. Aside from issues connected to animal ethics, Darwin's work contributed in other ways to the