Imagine a future in which human beings have become immune to all viruses, in which bacteria can custom-produce everyday items, like a drinking cup, or generate enough electricity to end oil dependency. Building a house would entail no more work than planting a seed in the ground. These scenarios may seem far-fetched, but pioneering geneticist George Church and science writer Ed Regis show that synthetic biology is bringing us ever closer to making such visions a reality. In Regenesis, Church and Regis explore the possibilities—and perils—of the emerging field of synthetic biology. Synthetic biology, in which living organisms are selectively altered by modifying substantial portions of their genomes, allows for the creation of entirely new species of organisms. Until now, nature has been the exclusive arbiter of life, death, and evolution; with synthetic biology, we now have the potential to write our own biological future. Indeed, as Church and Regis show, it even enables us to revisit crucial points in the evolution of life and, through synthetic biological techniques, choose different paths from those nature originally took. Such exploits will involve far more than just microbial tinkering. Full-blown genomic engineering will make possible incredible feats, from resurrecting woolly mammoths and other extinct organisms to creating mirror life forms with a molecular structure the opposite of our own. These technologies—far from the out-of-control nightmare depicted in science fiction—have the power to improve human and animal health, increase our intelligence, enhance our memory, and even extend our life span. A breathtaking look at the potential of this world-changing technology, Regenesis is nothing less than a guide to the future of life.