This dramatized documentary illustrates the evolution of humanity using animated sequences, narration and live-action vignettes. An animated sequence depicting the first single cell dividing over one billion years ago and evolving into early man, leads into a live action sequence of museum tour guide Cathy describing the development of our species. In the museum, a young man, Lee, views the life-sized models illustrating the various stages of early Homo sapiens, finally removing his business suit and stepping naked into the last, empty display case. In the following scene, Lee is seen as a soldier in Vietnam with his friend Arnie Dickerson, who muses on being back in the jungle after twenty-five million years of evolution, while in the museum, Cathy explains that once man stood upright, his hands were free to use weapons and the species evolved from fruit picker to hunter. Cathy adds that this advancement led to bonding or love. An animation then illustrates instances of early infidelity in mated pairs when the men go off to war. Next, a live-action flashback shows Lee and Arnie in the college bookstore. Lee is unprepared for his English Literature class assignment, needing either a quote from erotic poetry or prose by a major writer. When the boys get in line behind fellow student Cathy, Arnie picks up a copy of the anthropology book The Naked Ape and embarrasses Lee by quoting a passage about male genitalia, but Cathy is unoffended, responding casually with a fact about gorilla mating habits. As he and Lee walk across campus, Arnie continues to read aloud about how the rapid advance of civilization allowed inadequate time for human sexual behavior to adjust and that all basic urges are 25,000 to 30,000 years behind society’s dictates. Soon after, Lee and Cathy enter their English Literature class where the professor explains that erotic literature is popular because it bypasses the sexual restraints of society and that if people would live out their fantasies as healthy animals, traffic in pornography would drop to nothing. As the students stand one by one to read their passages to the class, Lee reads to himself about human courtship in The Naked Ape , with scenes of an unfolding relationship between Lee and Cathy illustrating the text and beginning a series of fantasy sequences: As Cathy reads her quote from The Song of Solomon , Lee imagines the class made up of only women, who gaze at him adoringly. Next, when the professor uses text from The Naked Ape to describe how privacy is sought during the copulatory phase of courtship, Lee sees the class as composed exclusively of men, who whoop with approval as he follows Cathy to the classroom door. When Cathy takes Lee’s hand, they fall through the open door into darkness as their clothes fall off in slow motion, finally revealing them lying naked together in bed after having had sex. There, Cathy compares the mating rituals of humans to other primates and she and Lee discuss the variety of primate orgasms as they walk down the aisle of a church at their wedding. The minister joins the dialogue about orgasms and their effect on fertilization and Cathy concludes that the naked ape is the sexiest primate alive. After Lee and Cathy consummate their marriage, Lee finds himself back in class with the professor waiting for him to read his passage aloud. Lee reads from The Naked Ape about how human copulation is primarily concerned with bonding rather than producing offspring, naturally leading to sexual experimentation for long-mated pairs. After class, Lee and Cathy discuss over-population as they walk through a gay power rally. An animation then illustrates the invention of clothing and a montage uses photographs of Lee and Cathy to show centuries of changing styles of clothing and physical beauty, finally returning them to their modern-day appearances. Next, Lee is seen as a business executive who restrains his sexual attraction to his new assistant, “Cathleen,” who is really Cathy in a wig, and then leaves for a weekend in the country with his wife, Cathy. After Lee and Cathy walk out of the building and jump into a pool in the courtyard, an animated sequence shows a cave couple come up out of the water. As Cathy’s narration describes humanity’s creative urge, footage of a child drawing turns into cave paintings and then becomes a montage of art through the ages. This is followed by footage of school children learning foreign languages, an opera singer performing and a hand writing mathematical equations on a chalk board. After an animation shows a cave man stringing a bow, which makes a musical sound, music is heard as footage of various musicians playing their instruments is shown. Next, Cathy states “we have even disciplined our bodies in search for form and beauty” which introduces a long sequence of gymnasts performing. After this, Lee and Arnie enter an army recruiting station with other young men as Cathy declares that the irony of man’s superior mentality is that it could cause the race to exterminate itself by the end of the century. As the recruits take their physicals, Cathy compares the class systems of most species of monkeys and apes in which the dominant male defends the colony, to humans who expect the lesser males to defend it with their lives. Human aggression is examined through a montage of war toys and footage of animal confrontations, followed by images of Mussolini, Hitler and armies doing battle. After many tests, Arnie tries to evade the draft by telling the psychiatrist that he would do anything to avoid conflict with an enemy and in the process, describes how primates display aggression and submission. Despite his attempts, Arnie is accepted into the army, as is Lee. Back in the jungle, soldiers Lee and Arnie hear the sergeant’s whistle and begin to look for the enemy as Cathy’s narration explains that men first made weapons and hunted over 450,000 years ago. Cathy continues to describe how the aggressive nature of the hunt has never changed, as an animated sequence shows primitive men pursuing and killing elephants, followed by live action scenes of hunting, bullfighting and gang fighting. Then back in the jungle, Lee is shot in the head, falls dead and Arnie cradles him in his arms. Back in the darkened museum, Lee stands naked in the glass case next to an empty case waiting to be filled.