Understanding Human History is a history of humanity, beginning about 100,000 years ago and going through the 20th century. It includes discussions of developments in every major area of the world. Unlike other books on world history, it explicitly discusses racial differences in intelligence, and explains how, why, and when they arose. The book also discusses the many consequences that those differences have had on human events, starting in prehistoric times and continuing to the present. The book includes an abundance of data and tables, together with sixteen maps, three tables, an extensive bibliography, and a thorough index.