This comprehensive guide to the body combines recent cell and molecular biology in a story that begins with the first life on earth. With a simple text and illustrations, it aims to make science fun. The book explains how we breathe, move, eat, reproduce, sense, think and feel, and how we defend ourselves against enemies from inside and out. It focuses on the role cells play in the body, describing how human cells are similar to those of every other living thing on this planet, and to the cells that were the first life on earth.