Book excerpt: In 2005, J.C. Hallman came across a scientific paper about "Pleistocene Rewilding," a peculiar idea from conservation biology that suggested repopulating bereft ecosystems with endangered "megafauna." The plan sounded utterly utopian, but Hallman liked the idea as much as the scientists did—perhaps because he had grown up on a street called Utopia Road in a master-planned community in Southern California. Pleistocene Rewilding rekindled in him a longstanding fascination with utopian ideas, and he went on to spend three weeks at the world's oldest "intentional community," sail on the first ship where it's possible to own "real estate," train at the world's largest civilian combat-school, and tour a $30 billion megacity built from scratch on an artificial island off the coast of Korea. In Utopia explores the history of utopian literature and thought in the narrative context of the real-life fruits of that history.