Maintaining the coherence of the distinction between nature and artefact has long been central to environmental thinking. By building genomes from scratch out of 'bio-bricks', synthetic biology promises to create biotic artefacts markedly different from anything created thus far in biotechnology. These new biotic artefacts depart from a core principle of Darwinian natural selection – descent through modification – leaving them with no causal connection to historical evolutionary processes. This departure from the core principle of Darwinism presents a challenge to (...) the normative foundation of a number of leading positions in environmental ethics. As a result, environmental ethicists with a commitment to the normative significance of the historical evolutionary process may see synthetic biology as a moral 'line in the sand'. (shrink)