When faced with the choice between the simplicity of reproduction through cloning and the fragility of sexual reproduction, biological evolution chose the latter.Why was sex invented? How did it evolve? The mystery of the appearance and the evolution of sex take us on a journey through time, from the origins of life to the present day.This film gives a modern scientific approach to the birth of the couple and, the origins of the other. Throughout the film, science takes on a poetic and philosophic aspect and science is seen as a tool for though, a way of learning about life.