According to "Race: The Power of an Illusion," only one human species exists. The documentary's first episode, "The Difference Between Us," examines racial categorization throughout history and how people view and experience the world. The experts interviewed for the video claim that the average person can classify people into different groups based on little more than their appearance. They point out that these traits only make up a small part of what it is to be human and that cultural and environmental elements set people apart. Researchers interviewed for the documentary conclude that human populations' continuous mixing and development renders the concept of "biologically pure" races a myth.