In this program, Desmond Morris analyzes the biological nature of love, with its attendant patterns of behaviour and signals of health and fertility that have evolved to ensure pair-bonding and genetic survival. The pre- and post-pubescent periods of sexual maturation, the stages of courtship, and the aesthetics of physical beauty are studied, along with the anatomical mechanics of sexual arousal and copulation. In addition, the stresses placed on couples by life in an urbanised, crowded world are explored.