Sui generis
Sui generis (; ) is a Latin phrase that means "of its (his, her, their) own kind; in a class by itself; unique."
Social teachings of Pope Pius XII
In 1950, Pius XII promulgated "Humani generis" which acknowledged that evolution might accurately describe the biological origins of human life, but at the same time criticized those who use it as a religion, who "imprudently and indiscreetly hold that evolution... explains the origin of all things". While "Humani generis" was significant as the first occasion on which a pope explicitly addressed the topic of evolution at length, it did not represent a change in doctrine for the Roman Catholic Church. As early as 1868, Cardinal John Henry Newman wrote, "the theory of Darwin, true or not, is not necessarily atheistic; on the contrary, it may simply be suggesting a larger idea of divine providence and skill." The encyclical issues a clear no to another scientific opinion popular at the time, polygenism, "the scientific hypothesis that mankind descended from a group of original humans."