The scope of Carl Zimmer’s book is as vast as its subject matter—the nature of life itself. Using Escherichia coli as a humble tour guide, Zimmer takes the reader on a journey that spans the history of modern biology. This book serves as a primer on how we have come to learn what we know about how life works from studying a single-celled bacterium. With equal measures of precision and poetry, subjects from evolution to synthetic biology are covered with enough detail to satisfy biologist and layperson alike. Effortlessly weaving stories of scientists and their times with the pressing biological questions of the day, Zimmer presents experimental evidence without ever losing sight of the big questions—who are we and how did we get here? In the process, the reader not only learns about what we know about life, but also how we found out. This book is geared towards a general audience, and does not require any previous knowledge of biology. Zimmer’s prose informs and invigorates the imagination while awakening our collective sense of wonder at being alive.
Beginning with the discovery of E. coli in 1885, Zimmer neatly expounds on how the “story of E. coli and modern biology are intertwined” first by examining the nature of the gene, the genetic code, organization of DNA structure, and the role of bacteriophage. This is followed by forays into the chemical geography of cells, metabolism, motility, biofilms, and gene regulation. The life of an E. coli cell is scrutinized from its birth and growth until it enters its final phase of aging and decay. The first few chapters of the book are reminiscent of an updated 21st-century footnote to the classic Lives of a Cell by Lewis Thomas. However, Microcosm delves deeply into each subtopic, providing the reader with experimental evidence to support Jacob Monod’s claim that “what is true for E. coli is true for the elephant.”
Another major theme in the book is how new species form and what we can learn by watching evolution “real time” in E. coli. The idea that “members of a species are individuals with the same essence” is challenged by the numerous guises of E. coli, whether as friend (the harmless laboratory strain K12) or foe (the deadly strain O157:H7). We are reminded that evolution “blurs the line between killers and protectors.” Scientists have studied the narrative history written in the genome of E. coli and reveal “open source evolution” being driven through horizontal gene transfer. Describing life as a “braiding stream of genes,” Zimmer demystifies the reading of genomes with an apt metaphor. Rather than thinking of a genome as an instruction manual, he regards it as a “recycled book known as a palimpsest” with all of the history of the organism written and rewritten through the ages. From a fascinating discussion on deciphering genomes, the book then explores the essential role of E. coli in the modern age of biotechnology and synthetic biology. Some controversial issues pertaining to genetic engineering and creationism are briefly raised.
The only drawback of the book is its lack of supporting figures in some chapters. While there are several simple figures showing the circuits controlling flagellar assembly, an entire discussion of evolution and the “tree of life” lacks any figures at all. Even with the vivid prose descriptions, a few more visual treats would have been appreciated, particularly by a general audience. This book is highly recommended for college-level biology courses. Rather than assigning the entire book, selected chapters could be used as reading assignments for class discussions. There are also many excellent examples and bibliographic resources that may be helpful for instructors who want to assign primary research articles on specific topics in microbiology. Microcosm should be read by anyone who wants to be an informed citizen in the age of molecular biology.