by Zoe Pollock

John Farrell celebrates the 60th anniversary of "Humani Generis", the papal encyclical (or pastoral letter) that established the Catholic Church's official relationship with Darwinian evolution, written by Pope Pius XII in 1950. While recognizing the Pope's foresight, Farrell also points out a slight problem in the church's position today: 

While Pius was willing to concede that there was reason to believe the human body was the product of evolution, he was adamant that the special status of Adam as the father of the human race should not be a matter of question. "For the faithful," he wrote, "cannot embrace that opinion which maintains either that after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all or that Adam represents a certain number of first parents."

Pius declared that it was not apparent how such a theory of a founding population of humans, and not a single couple, could be reconciled with original sin. That Catholic doctrine regards the Fall as an historical rebellion against God; a sin actually committed by an individual and which is passed on through the generations from him to all men and women.

Subsequent research into genomics, however, has settled this question against Pius. It's not that scientists cannot trace human ancestry back far enough to an Adam and Eve; it's that in principle, the level of genetic variation present in the species today rules out a founding population with fewer than several thousand individuals.

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