Nicolas Steno

Nicolas Steno (Danish: Niels Stensen; latinized to Nicolaus Stenonis) (January 10, 1638 - November 25, 1686) was a pioneer in both anatomy and geology.

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Early career

Steno was born in Copenhagen, and after completing his university education in the city of his birth, set out to travel through Europe; in fact, he would be on the move for the rest of his life. In the Netherlands, France, and Italy he came into contact with prominent physicians and scientists. These influences led him to use his own powers of observation to make important scientific discoveries. At a time when scientific questions were mostly answered by appeal to ancient authorities, Steno was bold enough to trust his own eyes, even when his observations differed from traditional doctrines.

Steno first studied anatomy, beginning with a focus on the muscular system and the nature of muscle contraction. He used geometry to show that a contracting muscle changes its shape but not its volume.

Contributions to paleontology and geology

In October 1666 two fishermen caught a huge shark near the town of Livorno, and Ferdinando II de' Medici, Grand Duke of Tuscany, ordered its head to be sent to Steno. Steno dissected the head and published his findings in 1667. He noted that the shark's teeth bore a striking resemblance to certain stony objects, found embedded within rock formations, that his learned contemporaries were calling glossopetrae or "tongue stones". Ancient authorities, such as the Roman author Pliny the Elder, in his Naturalis Historiae, had suggested that these stones fell from the sky or from the moon. Others were of the opinion, also following ancient authors, that fossils naturally grew in the rocks. Steno's contemporary Athanasius Kircher, for example, attributed fossils to a "lapidifying virtue diffused through the whole body of the geocosm", consided an inherent characteristic of the earth — an Aristotelian approach. Fabio Colonna, however, had already shown in a convicing way that glossopetrae are shark teeth^[1], in his treaty De glossopetris dissertatio published in 1616^[2]. Steno added to Colonna's theory a discussion on the differences in composition between glossopetrae and living sharks' teeth, arguing that the chemical composition of fossils could be altered without changing their form, using the contemporary corpuscular theory of matter.

Steno's work on shark teeth led him to the question of how any solid object could come to be found inside another solid object, such as a rock or a layer of rock. The "solid bodies within solids" that attracted Steno's interest included not only fossils, as we would define them today, but minerals, crystals, encrustations, veins, and even entire rock layers or strata. He published his geologic studies in De solido intra solidum naturaliter contento dissertationis prodromus, or Preliminary discourse to a dissertation on a solid body naturally contained within a solid in 1669. Steno was not the first to identify fossils as being from living organisms; his contemporaries Robert Hooke and John Ray also argued that fossils were the remains of once-living organisms.

Steno, in his Dissertationis prodromus of 1669 is credited with three of the defining principles of the science of stratigraphy: the law of superposition: "...at the time when any given stratum was being formed, all the matter resting upon it was fluid, and, therefore, at the time when the lower stratum was being formed, none of the upper strata existed"; the principle of original horizontality: "Strata either perpendicular to the horizon or inclined to the horizon were at one time parallel to the horizon"; the principle of lateral continuity: "Material forming any stratum were continuous over the surface of the Earth unless some other solid bodies stood in the way"; and the principle of cross-cutting discontinuities: "If a body or discontinuity cuts across a stratum, it must have formed after that stratum."^[3] These principles were applied and extended in 1772 by Jean-Baptiste L. Romé de l'Isle.

Another principle, known simply as Steno's law, or Steno's law of constant angles, states that the angles between corresponding faces on crystals are the same for all specimens of the same mineral, a fundamental breakthrough that formed the basis of all subsequent inquiries into crystal structure.^[4]

Religious studies

Steno's questioning mindset also influenced his religious views. Having been brought up in the Lutheran faith, he nevertheless questioned its teachings, something which became a burning issue when confronted with Roman Catholicism while studying in Florence. After making comparative theological studies, including reading the Church Fathers and by using his natural observational skills, he decided that Catholicism, rather than Lutheranism, provided more sustenance for his constant inquisitiveness. Steno converted to Catholicism. He was ordained a priest, later made a bishop by the Pope, and sent to mission in Lutheran North Germany. He first worked from the city of Hannover, meeting Gottfried Leibniz, before moving to Hamburg. Steno tried to satisfy his curiosity about mankind and the universe through good works. After years filled with difficult tasks and the observations of suffering, Steno died at Schwerin in 1686.

Steno's landmark theory that the fossil record was a chronology of different living creatures in different eras was a sine qua non< for Darwin's theory of natural selection.

Steno's life and work has been studied but rarely taught, in particular since the late nineteenth century, and his piety and virtue have been especially evaluated with a view to an eventual canonization. In 1987, he was declared "beatus" - the first step to being declared a saint - by Pope John Paul II. He is thus now called by Catholics Blessed Nicolas Steno.

Legacy

The Steno Museum in Århus, Denmark, named after Nicolas Steno, holds exhibitions on the history of science and medicine. It also operates a planetarium and a medicinal herb garden. Impact craters on Mars and the Moon are named in his honor. In 1950 a school, the "Niels Steensens Gymnasium", was founded on a Jesuit monastery that was co-founded by Steno.

Notes

Major works

• Concerning Solids naturally contained within solids (1669)
• Elementary Mylogical Specimens (1669)
• Anatomical Observations (1662)
• Discours de Monsieur Stenon sur L'Anatomie du Cerveau ("M. Steno's lecture on the anatomy of the brain", Paris 1669)

References

• The Seashell on the Mountaintop: A Story of Science, Sainthood, and the Humble Genius Who Discovered a New History of the Earth by Alan Cutler, 2003 ISBN 0-525-94708-6
• Blessed Nicholas Steno (1638-1686). Natural-History Research and Science of the Cross by Frank Sobiech, in: Australian EJournal of Theology, August 2005, Issue 5, ISSN 1448-632 (http://dlibrary.acu.edu.au/research/theology/ejournal/aejt_5/Sobiech.htm)
• Steno article at UC Berkeley
• Niels Stensen