Abstract

The opening of the archives for the pontificate of Pius XII makes it possible to see the history of the drafting of the encyclical _Humani generis_, the first document in which the universal magisterium of the Catholic Church addressed the question of evolution. Although its acknowledgment that the question of the evolutionary origin of the human body was, provisionally, theologically open generated no controversy at the drafting commission, the definitiveness of its reservations about monophyletic polygenism generated a disagreement resolved only by Pope Pius. An incident in 1955 reinforces these conclusions about the proper interpretation of the encyclical.