Anyone interested in the possibility of intelligent extraterrestrial life will love this book. Rarely does one find a book with such insight, breadth, and beauty. My favorite chapter is "Alien Sex" which actually taught me a lot about the bizarre sexual behaviors and anatomies of Earth creatures. One of the figures shows magnifications of sperm from various Earth animals, which should fascinate readers because of the incredible diversity.
Another favorite chapter deals with how we would communicate with aliens. Cliff Pickover gives the reader a number of difficult tests -- hypothetical mathematical signals beamed to Earth by aliens. He asks us if we can decode them. My friends and I are still working on the following test: "Aliens are waiting for humanity to replace the question mark with the next value in the sequence before they will consider us worthy for further communication: 77, 49, 36, 18, ?"
The answers are in the back of the book, but we're trying to solve them without looking.
The book's concluding words will send a shiver up your spine.