Book excerpt: Through simple yet engaging language and detailed images and charts, readers will explore the work of Aristotle, Linnaeus, Darwin, and other well-known, and some not so well-known, figures throughout history who tried to make sense of the natural world, as well as the breakthroughs and technologies that allow scientists to study organisms down to the genetic level. This book supports the Next Generation Science Standards on heredity and biological evolution by helping students understand how mutations lead to genetic variation, which in turn leads to natural selection. In addition, informative sidebars, a bibliography, and a Further Reading section with current books and educational websites will allow inquisitive minds to dive deeper into the evolutionary relationships among organisms.