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The Scientist Saint Who Discovered Deep Time
Nicholas Steno and the beauty of the unknown.
by Joshua M. Moritz
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Once upon a time, scientists believed that the planet Earth was eternal. This was quite an ancient view, descending from an honorable philosophical pedigree passed down through the intellectual line of Aristotle. Aristotelian uniformitarians held that the processes of Earth were eternal and cyclical with, as James Hutton declared, “no vestige of a beginning, and no prospect of an end.”1 Apart from a leap of faith, no one could conceive of a time before there were seasons, or mountains and rivers or before humans existed. Skeptics of such faith assumed the uncreated eternity of the cosmos and the Earth, along with the eternal perpetuity of human beings.2
Nicholas Steno, a founder of the geosciences, was the first to use science to challenge this Aristotelian view of the Earth and its inhabitants. As one of the most dexterous dissectors and adept anatomists of his age, Steno was also an expert excavator who connected his knowledge of biology with key insights into how fossils relate to different layers of sedimentary rock. Discovering “that the crust of the earth contained an archive of its most ancient history,” Steno inaugurated “an intellectual revolution that was as profound as that of Galileo and Copernicus.”3 And he sparked this revolution through the inspiration of his faith.
Hearts, Brains, and the Birds and Bees
The Danish polymath Niels Stensen (Nicolaus Stenonis in Latin and Steno in English) was an exceptionally gifted scientist who made pioneering contributions in numerous fields. As an anatomist, Steno’s delicate touch and sharp sight enabled him to discover structures and relationships that evaded clumsier hands and duller eyes. Accomplishing his first major anatomical discovery—the duct of the parotid gland (the ductus Stenonianus)—during his first independent dissection, Steno would go on to discover the lachrymal gland and duct, the cause of tears, the true nature of muscular tissue, and the mechanics of muscular contraction.
Against the ancients, Steno demonstrated the function of the heart as a muscle that pumps blood at the center of the circulatory system. Steno’s lectures on brain anatomy—where he rejected ancient speculations about animal spirits and criticized René Descartes's understanding of the pineal gland—oriented neuroscientists for generations to come.4 Advocating the need for studying the brain through a “comparative, developmental, and pathological convergent approach,” Steno elaborated complex models of the brain to explain its multifaceted function and contended that the brain is the principal organ of the human mind.5
Steno also made significant discoveries in the area of reproductive biology. He revealed the vitelline duct of the human embryo, introduced the term “ovary,” and discovered the follicles of the ovary.6 In 1667, he argued—against Aristotle, Galen, and Hippocrates—that the ovary in female mammals produces eggs and that it corresponds to the egg-producing organs of birds and reptiles.7 Going against the ancient anatomical tide, Steno thus made a strong scientific case that the role of women in reproduction is just as significant as that of men.
Delving into Deep Time
While he was one of the foremost anatomists and biologists of his age, Steno is primarily remembered for founding the science of geology and for his groundbreaking discoveries in that field. Steno’s launching of the geological sciences began with his dissection of a giant shark’s head. Having studied the perishable organs of the head first and then carefully examining the more durable features such as teeth, Steno revisited the old mystery of the nature of fossil objects that looked like small tongues called “tongue-stones.”8 In Steno’s day, the Aristotelian experts believed that fossil seashells and “tongue-stones” found embedded in mountaintops grew naturally within the earth and that they never belonged to living animals. Steno, however, became convinced that such fossils had an organic origin, and he demonstrated that there was no evidence for their growth in situ within the rocks. Steno showed that tongue stones were, in reality, the teeth of ancient sharks, and since they often showed signs of tooth decay, this implied that they were not being formed at the present time but were relics of an earlier period.
Having realized the connection between fossils and living animals, Steno devoted himself to investigating the relationship between fossils and the layers of rock within which they were embedded. He soon discovered that the different types of strata had different kinds of fossils and that one could predict what types of fossils would be discovered based on the rock types. From this, Steno developed the fundamental principles of the science of stratigraphy and introduced the concept of what is today known as “the geologic column.”
Steno recognized that the layers of rock that entombed fossil shells and shark teeth were made by the gradual accumulation of sediment, and he understood that each layer embodied a vast span of time in the past. Although he knew no way to precisely measure the number of years or millennia involved, it was clear to him that the layers formed a definite sequence of past ages—where the lowest layer had been formed first, and the highest had been formed more recently. These layers recorded a succession of past environments and animal types that no longer existed. Steno discovered that the Earth had a true history written in stone, layer by layer and that there was a “deep time” of millions or billions of years before humans ever existed.9
Finding God in the Fossils
In his discovery of deep time and Earth history, Steno explicitly compares the biblical and geological narratives. Instead of seeing a conflict between the “Book of Nature” and the “Book of Scripture,” though, Steno found that both books reveal “that the history of Earth had a direction and an identifiable beginning”—with a progression of various lifeforms appearing on the geological scene before humans eventually appear. Because the oldest strata lack fossils, Steno reasoned that these rock beds “must have been deposited before the creation of animals.” He thus interpreted the geological record as a “strong vindication” of Scripture. Had the oldest layers of sediment in Steno’s research been as “abundantly fossiliferous as the youngest strata,” the layers of strata could have been used to support the eternally cycling Earth of Aristotle and the Uniformitarians.10 Such was not the case, however.
Far from being a straight-jacket that hindered Steno’s development of geologic history and his understanding of the significance of fossils, the biblical understanding of linear time had the opposite effect.11 In the sixteenth and early seventeenth centuries, the eternity of the cosmos was generally assumed, and cosmological debates were conducted largely within philosophical frameworks that discouraged questions of the origin and development of the Earth. In the Aristotelian and Uniformitarian views, Terrestrial processes were thought to be cyclical, continuous, and to take place on an infinite time scale. The changes on Earth’s surface were not seen as progressive, historical, or directional but were understood to be like the incessant and regular movements of the timeless heavens. Beginning with Steno, the idea that the Earth had had a history first entered geologic debate—and it entered not from the realm of science or philosophy but from that of theology.12
The concept of linear or directional history was characteristic of Jewish and early Christian theological thought, and it is from here that Steno drew his inspiration for interpreting the scientific facts. All throughout his life, Steno was deeply devout—so much so that he was appointed a Bishop and was even venerated as a saint after his death—and his attempt to harmonize his geological observations with scriptural history was no insincere or forced reconciliation. On the contrary, it was for him “a natural synthesis of two equally valid and complementary sources of evidence—the Book of God’s Word and the Book of God’s Works.”13 Far from undermining the Biblical account, Steno’s discovery of deep time profoundly strengthened his faith in sacred history. For Steno, both science and religion “were an occasion not for arrogance, but humility,” and even though he was one of the most knowledgeable persons in the world, he firmly believed that “what is unknowable is far more beautiful.”14
About Joshua M. Moritz
Joshua M. Moritz, Ph.D., is Lecturer of Philosophical Theology and the Natural Sciences at the Graduate Theological Union in Berkeley, Adjunct Professor of Philosophy at the University of San Francisco, and Managing Editor of the journal Theology and Science.