Is there life on other planets? How similar is extraterrestrial life to life on Earth? These questions, until recently confined to the pages of science fiction books, are now the legitimate subject matter of extensive scientific research. Recent discoveries of extrasolar planets, life under extreme conditions and possible life on other celestial bodies have heightened public interest on the origin of life. In this volume the author offers a detailed discussion of research devoted to the origin of life. The book's first part offers an overview of the main ideas on the origin of life as they have developed from antiquity until the 20th century. The second part explores the major prevailing and often contentious scientific theories that are fuelling the origin-of-life debate within and beyond the scientific community. To come full circle, the author returns to the age-old question: is there life beyond Earth? and examines the most recent scientific discoveries that suggest possible life elsewhere in the universe.