A PLANET OF VIRUSES | Carl Zimmer. University of Chicago Press, 128p. Besides being omnipresent, viruses have contributed to the evolution of the human genome and are among the many fascinating insights this slim booklet offers. Viruses are a part of our identity, regardless of our willingness to identify as such. We are, in the writer’s phrase, “an inextricable blend of mammal and virus.” Zimmer outlines the vital role viruses have played in human development. Smallpox, the only virus to have been eliminated (in the wild), killed over 300 million people. The first recorded description of a viral cold was 3,500 years ago in Egypt. As a science writer, Zimmer makes accessible the biology and functionality of a virus, its life-cycle, and its replication. The author charts a journey through deep caves, vast oceans, and the prehistoric landscapes of viral history. The epidemic storylines are the most familiar and relatable; however, the entire work is an excellent start for those of us who have forgotten most of our high school biology.