It was 1859 when Charles Darwin published his book “On the Origin of Species.” After years of study with Alfred Wallace, the naturalist released his theories on the development of life and natural selection. Natural selection, often referred to as “survival of the fittest,” points to the notion that creatures with beneficial traits for survival live long enough to breed and pass down these traits to offspring. Those who perish, due to lack of desirable traits, do not live long enough to breed. Over time, Darwin theorized, these traits would lead to micro changes in species. And these micro changes could lead to macro changes, through which one species could evolve into a different species.

The idea of a changing earth and its inhabitants didn’t start with Darwin. Scientists studying geology had long questioned the literal nature of the book of Genesis because of the discovery of fossils and the study of rock formations. One such scientist was Nicolas Steno, a Danish scientist, who would eventually convert to Catholicism and become a priest and bishop. Steno is considered one of the founding fathers of geology, establishing a number of principles in regard to geological strata.

Today, most scientists consider Darwin’s theory of natural selection an accurate mechanism of evolution, but not the only mechanism. Other considerations include genetic drift, which is the limiting of genes based upon isolation in groups of species.

Still, many faithful hold to creationism, a literal interpretation of Genesis.

Before the encyclical “Humani Generis” written by Pope Pius XII in 1950, the church never took an official position on the evolution of humans. Pope Pius’ statement was considered neutral on the topic.

“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,” wrote Pope Pius.

The holy father argued vehemently, however, that study of evolution be done thoughtfully, giving weight to both theories of evolution and creationism.

He went on to add that polygenism, accepting the belief that Adam in the “Book of Genesis” represented a group of men rather than a single man, cannot be embraced by Catholic faithful.

By the mid-1990s, two influential Catholic men, Pope John Paul II and theologian Cardinal Joseph Ratzinger — eventually Pope Benedict XVI — spoke more directly about evolution.

“Taking into account the scientific research of the era, and also the proper requirements of theology, the encyclical ‘Humani Generis’ treated the doctrine of ‘evolutionism’ as a serious hypothesis, worthy of investigation and serious study, alongside the opposite hypothesis,” Pope John Paul II wrote in a letter to his pontifical academy of science in 1996.

“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 a hypothesis,” he continued.

“Pius XII underlined the essential point: If the origin of the human body comes through living matter which existed previously, the spiritual soul is created directly by God.”

“The sciences of observation describe and measure, with ever greater precision, the many manifestations of life, and write them down along the time-line. The moment of passage into the spiritual realm is not something that can be observed in this way — although we can nevertheless discern, through experimental research, a series of very valuable signs of what is specifically human life,” wrote the pope.

In his commentary on creation and the fall, “In the Beginning,” published in 1990, then-Cardinal Ratzinger described the Bible as a religious book and not as a scientific explanation of creation.

“We cannot say: creation or evolution, inasmuch as these two things respond to two different realities,” Cardinal Ratzinger wrote.

“The story of the dust of the earth and the breath of God … does not in fact explain how human persons come to be but rather what they are. It explains their inmost origin and casts light on the project that they are. And, vice versa, the theory of evolution seeks to understand and describe biological developments. But in so doing it cannot explain where the ‘project’ of human persons comes from, nor their inner origin, nor their particular nature. To that extent we are faced here with two complementary — rather than mutually exclusive – realities.”

Church leaders are resistant to accept evolution that was not at the hands of divine design. The church has often led science to identify details of the history of life on earth, wrote Cardinal Christoph Schönborn in an editorial to the New York Times in 2005. But with reason, humans can discern purpose and design in the natural world.

“Evolution in the sense of common ancestry might be true, but evolution in the neo-Darwinian sense — an unguided, unplanned process of random variation and natural selection — is not,” wrote the cardinal.

“Any system of thought that denies or seeks to explain away the overwhelming evidence for design in biology is ideology, not science.”

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