Amazon.com Review "What is life?" asked physicist Edwin Schrodinger in an influential essay by that title published half a century ago. In this book, Franklin Harold ventures no definitive answers about what he calls "the supreme marvel of the universe." Instead, with wit and learning, he surveys the advances in scientific understanding about the nature of life since Schrodinger's time. Harold focuses closely on microorganisms, which, he observes, do not often figure in popular books of biology, perhaps because most general readers associate them only with disease and not with their many beneficial contributions to the world's workings. In fact, he suggests, the answer to Schrodinger's question is likely to be found at the microscopic level. Current evolutionary models derived from the study of ribosomal RNA from hundreds of species of plants and animals now point to the development of life from some cenancestor in a setting billions of years old, one in which "microorganisms rather than dinosaurs fill the horizon." The identity of that ancestor is not yet known, he writes; it may have resembled a bacterium, or it may have been a loosely organized assemblage of protocells "engaged in the promiscuous exchange of genetic information." Nothing concentrates the mind like tackling the largest of questions (What is life?) within the smallest of settings (the cell). In achieving this concentration, Harold invites general readers to join him on the very frontier of biological