In this intriguing and engaging narrative, readers learn that living organisms must adapt to survive as their surroundings change. Scientists believe that all forms of life developed from earlier types of living things through a process called evolution. By studying the developmental history of everything from single cell organisms to complex vertebrates, readers are presented with the evidence for evolution provided by the fossil record. Charles Darwin and the process of natural selection are discussed. In addition, the work of Gregor Mendel opens a window onto genetics and gets readers thinking about how genes work together to produce specific traits.