This book has been rather popular lately, and it is easy to see why - it is a very interesting study of the science that explains what we are and how we exist, from discussions on how the planet came to be, to how we nwork on a subatomic level. It is full of fascinating information and terrific stories about the odd personalities that have played such a major role in science.
Bryson gives appropriate credit to a similar book that is focused on geology - Annals of a Former World by the incomparable writer John McPhee.