Maybe we really are alone.That's the thought-provoking conclusion of Rare Earth, a book that is certain to have far-reaching impact in the consideration of our place in the cosmos.While it is widely believed that complex life is common, even widespread, throughout the billions of stars and galaxies of our Universe, astrobiologists Peter Ward and Donald Brownlee argue that advanced life may, in fact, be very rare, perhaps even unique.Ever since Carl Sagan and Frank Drake announced that extraterrestrial civilizations must number in the millions, the search for life in our galaxy has accelerated. But in this brilliant and carefully argued book, Ward and Brownlee question underlying assumptions of Sagan and Drake's model, and take us on a search for life that reaches from volcanic hot springs on our ocean floors to the frosty face of Europa, Jupiter's icy moon. In the process, we learn that while microbial life may well be more prevalent throughout the Universe than previously believed, the conditions necessary for the evolution and survival of higher life--and here the authors consider everything from DNA to plate tectonics to the role of our Moon--are so complex and precarious that they are unlikely to arise in many other places, if at all.Insightful, well-written, and at the cutting edge of modern scientific investigation, Rare Earth will fascinate anyone interested in the possibility of life elsewhere in the Universe, and offers a fresh perspective on life at home which, if the authors are right, is even more precious than we may ever have imagined.