Nicolaus Steno


In 1671, two years after its publication in Italy, De solido reached England. Members of the Royal Society of London, later known as one of the world’s most prestigious scientific bodies, quickly took notice. Henry Oldenburg, the society’s secretary, had the work translated into English, and it was soon passed to the polymath Robert Hooke for review. Hooke had reached conclusions similar to Steno’s about the origins of fossils, and the two could have become intellectual allies, but that didn’t happen. Brilliant but grouchy, Hooke accused Oldenburg—a long-time thorn in his side—of slipping his hypotheses to Steno. Hooke’s accusations were soon eclipsed by a published attack from another Royal Society member, a physician named Martin Lister.

Although Steno had provided a strong argument for the organic origin of fossils, he had made no real progress in determining the nature of “tricky” fossils, those that bore no resemblance to currently living organisms. Lister offered a prime example: ammonites. Relatives of modern cephalopods, ammonites bore some resemblances to the modern nautilus, but also striking differences. There was an explanation for this, one already suspected by the contentious Hooke: the ammonites differed so much from living mollusks because ammonites were extinct. But 17th-century Europe wasn’t ready for the notion of extinction; the concept would not achieve scientific respectability until the turn of the 19th century when it was articulated by the great French naturalist Georges Cuvier.

Lister’s criticisms must have been unpleasant, but the “support” of John Woodward was worse. Woodward was a successful physician and Royal Society member. After Steno’s death, he used—plagiarized, in fact—many of Steno’s arguments to bolster his own interpretation of Noah’s Flood during which, Woodward claimed, Newtonian gravity was suspended, causing the Earth’s solid matter to “instantly shiver into millions of Atoms and relapse into its primitive Confusion.”

Ammonite illustration

Martin Lister cited ammonites to refute Steno’s claims about fossilization. (Image from The Seashell on the Mountaintop by Alan Cutler)

The setbacks, however, proved temporary. In the 18th century, De solido was reprinted at least twice, in Latin and French, and miners and mineral surveyors began applying Steno’s principles to their work. By regarding the lowest rocks as the oldest and the highest rocks as the newest, an Italian miner named Giovanni Arduino classified the rock layers of the Alps into three categories. Primary rocks were the oldest and had no fossils. Secondary rocks consisted of tilted sedimentary layers with fossils. Tertiary rocks included still-horizontal sedimentary rocks, also containing fossils. Arduino didn’t relate these rock groups to biblical events, though they became linked in popular use, most people assuming that Secondary rocks resulted from Noah’s Flood.

As Steno’s principles gained acceptance, however, they began to undermine the biblical chronology he had believed. In 1720, chemist René Réaumur published a description of sediment layers composed mostly of broken shells. Because many of these layers were several meters thick, he argued that they could not have been deposited by a flood lasting, as the Bible described Noah’s Flood, less than a year. By the late 18th century, some geologists had also begun to question the antiquity of humankind compared to other forms of life. In deeper and therefore older sediment layers, they found “relics” of Noah’s Flood which, according to the Old Testament, happened after the creation of humans. So they should have found human remains in the older rock layers, too, but they didn’t; human remains appeared only in the youngest rocks. Even more amazing, fossil collectors found a menagerie of remains—of marine and flying reptiles, oddly-proportioned mammals, and a huge variety of invertebrates—recorded nowhere in history. An astonishing succession of life forms had apparently come and gone before humans arrived on the planet. By the close of the 18th century, the famous French naturalist Georges Buffon publicly described humans as recent arrivals on a planet roughly 75,000 years old. Privately, he estimated the planet’s age at closer to 10 million years. No one would know the Earth’s age until the 20th century, after the discovery of radioactivity enabled scientists to attach absolute ages to rocks. (In 1953, two independent studies estimated the age of the Earth at approximately 4.5 billion years.) Yet because of Steno’s principles, scientists could arrange fossils chronologically, and even locate rich seams of fossil fuel to power the 19th and 20th centuries.

The eventual discoveries of geology were all unimaginable to the 17th-century savant. Although King Frederick III died before Steno reached Copenhagen, the savant wound up there anyway. Steno missed Florence, and after two years, he petitioned the new monarch for permission to return. Permission granted, Steno returned to Tuscany and tutored a young Medici prince, but he wasn’t satisfied. In 1675, Steno took a vow of poverty and became a priest. He hoped for a simple life of pastoral duties, but the Catholic Church summoned him to Rome and made him a bishop in 1677. His new assignment was in northern Europe, converting Protestants to Catholicism in Germany, Norway, and Denmark. It was a tough assignment, and as before, he missed Florence.

Portrait of Steno as a bishop

Steno became a Catholic bishop in 1677. (Image from The Seashell on the Mountaintop by Alan Cutler)

Steno took his vow of poverty seriously, and acquaintances watched in dismay as he grew skinnier. A friend he had recently converted recounted finding Steno “without a house, without a servant, devoid of all life’s comforts, lean, pale and emaciated.” Over time, Steno’s self-denial took its toll, and he died at the age of 48. Three centuries after his birth, a group of Danish pilgrims appealed to Pope Pius XI to name him a saint. Pope John Paul II beatified Steno in 1988, putting the 17th-century savant on the road to sainthood.

In the last years of his life, Steno cared more about saving souls than studying rock strata, yet he never renounced his scientific work. Steno certainly could not have imagined where his geologic principles would lead over the next three centuries. Likewise, succeeding geologists, paleontologists, and even anatomists would have had a hard time imagining their fields of research without his pioneering insights.

  • References:
  • Cutler, Alan. The Seashell on the Mountaintop: A Story of Science, Sainthood, and the Humble Genius Who Discovered a New History of the Earth. New York: Dutton, 2003.
  • Ellis, Richard. Monsters of the Sea. New York: Alfred A. Knopf, Inc., 1994.
  • Rudwick, Martin J.S. The Meaning of Fossils: Episodes in the History of Paleontology. Chicago: University of Chicago Press, 1976.
  • Rudwick, Martin J.S. Scenes from Deep Time: Early Pictorial Representations of the Prehistoric World. Chicago: University of Chicago Press, 1992.

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Steno certainly could not have imagined where his geologic principles would lead over the next three centuries.