The position of the Roman Catholic Church on the theory of evolution by natural selection has changed over time.

Darwin's Origin of Species appeared during the papacy of Pope Pius IX, a religious conservative who introduced the new doctrine of papal infallibility during the First Vatican Council in 1869, and who was openly hostile to any scientific or political encroachment on religious authority. Stifling Catholic acceptance of evolution until the mid 20th century, Pius IX proclaimed:

"let him be anathema … [w]ho shall say that human sciences ought to be pursued in such a spirit of freedom that those may be allowed to hold as true their assertions, even when opposed to revealed doctrine." (Pope Pius IX, quoted by Stephen Jay Gould in Rock of Ages)

The Church, beginning in 1950 with Pope Pius XII's encyclical Humani Generis, took up a neutral position with regard to evolution:

"The Church does not forbid that… research and discussions, on the part of men experienced in both fields, take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter." [1]

In an October 22, 1996, address to the Pontifical Academy of Science , Pope John Paul II updated the Church's position to accept evolution of the human body:

"In his encyclical Humani Generis, my predecessor Pius XII has already affirmed that there is no conflict between evolution and the doctrine of the faith regarding man and his vocation… Today, more than a half-century after the appearance of that encyclical, some new findings lead us toward the recognition of evolution as more than an hypothesis. In fact it is remarkable that this theory has had progressively greater influence on the spirit of researchers, following a series of discoveries in different scholarly disciplines… The convergence in the results of these independent studies?which was neither planned nor sought?constitutes in itself a significant argument in favor of the theory." [2]

In the same address, Pope John Paul II rejected any theory of evolution that provides a materialistic explanation for the human soul:

"Theories of evolution which, because of the philosophies which inspire them, regard the spirit either as emerging from the forces of living matter, or as a simple epiphenomenon of that matter, are incompatible with the truth about man."