Evolution is often described as a "theory." While this is certainly technically true, it is misleading to dismiss evolution as "just a theory" (an unfounded idea), as opponents of evolution like to do. This illuminating work of popular science amply demonstrates that there are few more well-established facts in the scientific canon than that life evolved on earth. Walking the reader through the steps in the evolutionary process, the author uses plenty of real-world examples to show that not only does evolution happen, it must happen. The author analyzes evolution as the unintended consequence of three independent facts of the natural world that we can observe every day: (1) the fact of the replication of life forms (producing offspring); (2) the fact that offspring are not identical (variation); and (3) the fact that not all offspring survive (selection). Viewed in terms of this analysis, evolution is no longer debatable; in fact it has to occur. It is simply the inevitable consequence of three obvious, observable, factual natural phenomena. The book also covers new discoveries in evolution, many of which have occurred in the last twenty years of the "genomic revolution" and have strengthened Darwin's basic idea. In addition, the author discusses complex theoretical issues such as speciation, phyletic gradualism vs. punctuated equilibrium, the "Evo-Devo" paradigm, and the concept of bauplane, as well as the facts of primate and hominid evolution. Well-organized, clearly written, and accessible, this book is ideal for students or any interested lay readers.