The early decades of the twentieth century were marked by widespread optimism about biology and its ability to improve the world. A major catalyst for this enthusiasm was new theories about inheritance and evolution (particularly Hugo de Vries's mutation theory and Mendel's newly rediscovered ideas). In Britain and the USA particularly, an astonishingly diverse variety of writers (from elite scientists to journalists and writers of fiction) took up the task of interpreting these new biological ideas, using a wide range of genres to help their fellow citizens make sense of biology's promise. From these miscellaneous writings a new and distinctive kind of utopianism emerged – the biotopia. Biotopias offered the dream of a perfect, post-natural world, or the nightmare of violated nature (often in the same text), but above all they conveyed a sense that biology was – for the first time – offering humanity unprecedented control over life. Biotopias often visualized the world as a garden perfected for human use, but this vision was tinged with gendered violence, as it became clear that realizing it entailed dispossessing, or even killing, ‘Mother Nature’. Biotopian themes are apparent in journalism, scientific reports and even textbooks, and these non-fiction sources shared many characteristics with intentionally prophetic or utopian fictions. Biotopian themes can be traced back and forth across the porous boundaries between popular and elite writing, showing how biology came to function as public culture. This analysis reveals not only how the historical significance of science is invariably determined outside the scientific world, but also that the ways in which biology was debated during this period continue to characterize today's debates over new biological breakthroughs.