The devil is in the theological details. And this is a key reason why, at the pastoral level, Catholics are still being taught an account of human origins that is essentially no different from what a Catholic in the sixteenth century was taught. While the Catechism acknowledges the use of figurative language in the Genesis account of Adam and Eve, the Garden of Eden, and the role of the serpent in bringing about the Fall, it retains the traditional belief that humanity is descended from a single pair, an historical Adam and Eve, and that they were exiled from Paradise—an existence without suffering or death—because of their rebellion against God in a single act of disobedience.

One way of dealing with the dissonance is simply to ignore or even deny the science. The influence of Evangelical churches that embrace creationism has clearly had an impact on Catholics, particularly in the United States. The last Pew survey (2013) showed that 26 percent of white U.S. Catholics do not believe that humans evolved over time. For U.S. Hispanic Catholics the number was even higher—31 percent.

At the other end of the spectrum, progressive theologians have argued that the time has come to discard the notion of original sin altogether. In his book Christianity in Evolution: An Exploration (2011), Fr. Jack Mahoney argues that, after Darwin, there is no longer a need or a place in Christian belief for the doctrines of the Fall, original sin, and human concupiscence resulting from that sin. John Haught and Ilia Delio have built upon Teilhard’s argument that sin, evil, suffering, and death were all going to be inevitable in a truly evolving cosmos. In their view, acknowledging this only enlarges the scale and importance of the redemptive power of Christ’s suffering, death, and resurrection.

In a more moderate vein, theologians such as the late Piet Schoonenberg and Herbert McCabe adopted what became known as a situationalist view of original sin. While letting go of the idea of an historical Adam and Eve, they advanced the idea that original sin was a state of spiritual impoverishment, a lack of grace, in which all human beings find themselves from the moment of birth, and which is perpetuated by the structural evils of the institutions in which their lives are embedded.

For scientists like Daryl P. Domning, a Catholic paleontologist and coauthor with the late Monika K. Hellwig of Original Selfishness: Original Sin and Evil in the Light of Evolution (2006), this approach is not very satisfying because it overlooks the very real nature of selfishness, programmed by natural selection not only into the human species from its origins, but also into all living species going back to the very origin of life itself. Far from setting aside Augustine’s notion of original sin as a real privation passed on by propagation, Domning argues that evolution grounds the idea even more concretely than the church’s tradition has since Trent. The theological difficulty here has to do with Teilhard’s suggestion that natural evil, like natural selection, was programmed into creation from the beginning—that the world never existed in a state of perfection prior to Adam’s Fall.

But apart from these theological complications, the fear of science in general must also be seen as one reason the church has been so slow to embrace evolutionary theory. As Josef Ratzinger pointed out in his book ‘In the Beginning...’: A Catholic Understanding of the Story of Creation and the Fall, many of the faithful fear the encroachments of science. Ever since Galileo,

...on the whole, the impression is given that the history of Christianity in the last four hundred years has been a constant rearguard action as the assertions of the faith and of theology have been dismantled piece by piece. People have, it is true, always found tricks as a way of getting out of difficulties. But there is an almost ineluctable fear that we will gradually end up in emptiness and that the time will come when there will be nothing left to defend and hide behind, that the whole landscape of Scripture and of the faith will be overrun by a kind of ‘reason’ that will no longer be able to take any of this seriously.

That the question has become a matter of pastoral concern is shown by the emergence of new efforts to promote dialogue between faith and science, and in particular to address the questions surrounding what science tells us of human origins. Take, for example, a new online resource created by a team of Dominicans, called Thomistic Evolution. Lead by Fr. Nicanor Austriaco, professor of biology at Providence College, the aim of the site is to provide a kind of modern quaestiones disputatae, in the style of the medieval scholastics, to answer point by point the challenges that modern evolutionary biology poses for doctrine. In particular, the Thomistic Evolutionists embrace Aquinas’s use of theological arguments of fittingness to reveal the meaning, beauty, and wisdom of God’s actions in the world.

For starters, they tackle the question of why Catholics should even accept evolution in the first place. Why, after all, should it be considered fitting for God to have created the world via the apparently “wasteful” process of evolution rather than by immediate special creation? The answer, according to the Thomistic Evolutionists, lies in secondary causality. In Aquinas’s view, secondary causality means that God “shares his perfections with his creatures by inviting them to participate in his causality, which in the world manifests itself in his governance of his creation. It is a greater perfection, and therefore, more fitting, for God to share His causality with His creatures, making them authentic causes that can cause by their own natures, than for God to remain the sole cause acting within the universe.”

While broadly accepting the consensus of contemporary science, Thomistic Evolution also reflects the Dominicans’ longstanding devotion to the Aristotelian philosophy of nature, which Aquinas integrated into Catholic theology. This philosophy of nature assumes that each species is clearly marked out according to its own unique attributes or essence, and that in the case of humanity this essence includes the metaphysical addition of a rational soul.

And this brings us to the greatest tension between Catholic doctrine and evolution: the church’s conception of human nature seems to require a more clear-cut origin for Homo sapiens than the fuzzy species boundaries acknowledged in evolution. One way to finesse this distinction is to concentrate only on the distinctiveness of the human soul and leave the human body to evolution. As Pope XII wrote in his 1950 encyclical Humani generis:

For these reasons the Teaching Authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, 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—for the Catholic faith obliges us to hold that souls are immediately created by God.

Austriaco believes that a Thomistic approach offers a way to embrace the science and yet still defend entirely the idea that all of humanity can be traced in descent to a metaphysically unique first man. In a recent essay for the American Catholic Philosophical Quarterly, he argues that the evolution of language suggests that modern human beings share an intrinsic essence that puts them into a unique natural kind of their own—one distinct even from the early modern humans that made up our biological species Homo sapiens. He notes that it’s important to distinguish ourselves from our earlier ancestors, because in his telling they did not possess the capability of abstract symbolic thought. That arose, in Fr. Austriaco’s view, with the birth of a unique man, with a unique capacity for language.

It’s a bold thesis. Some scientists I’ve spoken with tell me this theory tries too hard to save Adam by positing special assumptions. It’s also undercut by the most recent evidence that Neanderthals, too, were capable of symbolic thought and representation. The cave paintings in Spain have now been dated to 64,800 years ago—before Homo sapiens had moved into Europe.

Philip Lieberman, a professor at Brown and the author of Toward An Evolutionary Biology of Language and The Theory That Changed Everything, points out that multiple lines of evidence show that language evolved over millennia, just like every other human trait. Far from being due to a sole faculty that might have emerged suddenly, the capacity for language relies upon many of the same neural processes that evolved to facilitate fine balance and motor capacity and the development of the key physical features that make human speech possible.

On the other hand, Domning agrees with the Thomistic Evolutionists on at least one point: the church does need to preserve a cohesive founding story because “we human creatures, embedded in history as we are, still need etiological myths, even in the twenty-first century—only now we demand of them not only mythic power, but historical concreteness as well.” But Domning thinks evolution provides this—and something more. “We want a metaphysics that does not just promise us a hopeful future, or even just help us deal with the imperfections of the actual present, as opposed to a perfect ‘eternal present’ in some timeless realm ‘above’ creation. Rather, our metaphysics must be adequate to embrace, and valorize, the actual past as well as the present and the future.”