From Fossils: Evidence of Vanished Worlds by Yvette Gayrard-Valy
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From Fossils: Evidence of Vanished Worlds by Yvette Gayrard-Valy |
Niels Stensen (also known as Nicolaus Steno) was born in 1638, in staunchly Lutheran Copenhagen. His youth was rough, marked by illness, his father's untimely death, financial instability, and the loss of many of his friends to the plague. The boy had an exceptional mind, though, and after hanging out in alchemy workshops, he eventually attended college. Though his interests ranged from chemistry to sketching snowflake crystals, he studied to become a physician.
Stensen's skill as a physician and anatomist became apparent while he was still a young man. He impressed high society with his dissections of horse eyes, a rare trick at parties. On a whim, the dissected a sheep's head and, almost by accident, discovered the duct of the parotid gland, which supplies saliva to the mouth. In later years, he uncovered the nature of muscle contractions, and the muscular nature of the human heart (thought by some to generate heat, not pump blood). Some adherents to the heart-as-furnace notion refused to accept Stensen's findings even after his personal demonstrations. Like his studies of the heart, Stensen's careful dissections of human brains disproved the speculations of no one less than Descartes.
Stensen went further than refuting the ideas of Descartes; he even rejected the Aristotelian elements of earth, water, air and fire. This ancient view assigned distinct shapes to the different elements: icosahedron for water, tetrahedron for fire, cube for earth, and octahedron for air. By examining grains of sand under a microscope, Stensen discovered that they had a variety of shapes: "pyramidal, pentahedral, cubic, heptahedra, trapezia . . ." Stensen recorded his observations in a manuscript he wrote in 1659, while still studying at the University of Copenhagen, Chaos. In this early work, he touched upon the modern understanding of the fractionation of the planet, the separation of of earth's matter thanks to the planet's heat.
The savant's remarkable achievements only continued. By 1666, Stensen had the opportunity to examine the head of a white shark, thanks to the patronage of the Grand Duke of Tuscany, Ferdinando II. When he wrote his description, Stensen noted that the animal's teeth bore a remarkable similarity to glossopetrae, or tongue stones. He suggested that tongue stones weren't what they had long been supposed (serpent tongues turned to stone by St. Paul) but were instead teeth that had once belonged to sharks. He also suspected a natural process had turned the teeth to stone, although he didn't know precisely what it was.
Making his case for fossil shark teeth wasn't a simple matter of showing their modern counterparts. In Stensen's time, many scholars and philosophers believed that fossils resulted from some creative force in nature. In those days, fossils were defined simply as natural (and sometimes manmade) objects dug out of the ground, so this explanation was partly true; Stensen himself recognized that crystals could grow inside rocks. If this explanation were true in every case, however, then the shark teeth should be new, having recently been made by the surrounding rocks. In fact, he showed the teeth were old — as evidenced by their decayed state — and therefore relics from an earlier time. He also pointed out that, unlike tree roots that grow into rock crevices, the teeth weren't deformed, nor did they cause cracks in the surrounding sediment. Stensen applied the same logic to other fossils, including numerous molluscan fossils found on mountaintops.
 From The Meaning of Fossils by Martin J.S. Rudwick |
A few years after identifying shark teeth, Stensen accomplished an even more outstanding feat: perhaps the world's first stratigraphic section, a diagrammatic section of the geology around Tuscany. Stensen relied on crustal collapse — since disproven — to explain the geology, but he established three principles still accepted today. The first was the principle of superposition, the crucial discovery that old rock layers underlie new rock layers. The second was the principle of original horizontality, that sediments are deposited as liquids, and like water, they are deposited horizontally, filling in irregularities at the bottom, but making a smooth surface at the top. The third was the principle of lateral continuity, that layers of sediment are continuous, unless a barrier prevents the sediments from spreading during deposition, or subsequent changes in the landscape break those sediment layers apart. Stensen also discovered that the oldest rocks at the bottom didn't have fossils, while the rocks at the top did, and concluded that the rocks at the bottom predated life on earth. In 1669, he published his findings in De solido, a 78-page book that completely changed, if not invented, the field of geology.
De solido, also known as Forerunner, was supposed to be an introduction to a much more in-depth work, but the bigger book never appeared. Stensen's interests shifted to religion, and after converting from Lutheranism to Catholicism, he became a priest. After he was ordained in 1675, he expected to remain a priest for the rest of his life, but Rome had other plans. Just two years later, he was made a bishop and sent to Germany. Born during the Thirty Years War, he spent some of the last years of his life ministering to the Catholics who had survived the protracted conflict. But ecclesiastical politics didn't appeal to Stensen, and he soon reverted to the simple lifestyle of a priest with a special emphasis on self-denial and physical punishment. An alarmed friend described Stensen's state as "without a house, without a servant, devoid of all life's comforts, lean, pale and emaciated." He wasted away to almost nothing and died, possibly from a kidney stone, at the age of 48. Centuries after his death, Danish pilgrims appealed to Pope Pius XI to make Stensen a saint, and the savant was beatified in 1988.
For more information:
The Seashell on the Mountaintop by Alan Cutler
Monsters of the Sea by Richard Ellis
Fossils: Evidence of Vanished Worlds by Yvette Gayrard-Valy
The Meaning of Fossils by Martin J.S. Rudwick
"Nicholas Steno's Chaos and the Shaping of Evolutionary Thought in the Scientific Revolution" by Gary D. Rosenberg in Geology Magazine, September 2006 issue
The Great Naturalists edited by Robert Huxley
Possessing Nature by Paula Findlen
Fossil Revolution by Douglas Palmer
The Lure of Antiquity and the Cult of the Machine by Horst Bredekamp
Narrative text and graphic design © by Michon Scott - Updated January 9, 2008