Today marks the 374th birthday of Nicolas Steno, a pioneer in geology and anatomy in the 17th century. Steno (Neils Stensen in the original Danish) was born in 1638 in Copenhagen, and after completing his university education in Denmark he spent the rest of his life travelling throughout Europe and collaborating with prominent physicians and scientists.
While the common approach of scientists at the time was to appeal to the ideas of Aristotle and Pliny, Steno was determined to examine evidence for himself and draw his own conclusions. He was guided in this by his religious convictions about God as Creator of the natural order.
Stressing the importance of investigation and observation, he wrote:
“One sins against the majesty of God by being unwilling to look into nature’s own works and contenting oneself with reading others; in this way one forms and creates for oneself various fanciful notions and thus not only does one not enjoy the pleasure of looking into God’s wonders but also wastes time that should be spent on necessities and to the benefit of one’s neighbor and states many things which are unworthy of God.”
Steno made important advances in anatomy and physiology, most notably in muscle research. He determined that the heart was a muscle (it was thought by many at the time to be a generator of heat), and also demonstrated geometrically that muscles under contraction do not increase in volume (they just change their shape).
But his biggest contribution to science is in the fields of geology and paleontology. After studying the similarities between living sharks and fossilised shark teeth, he decided that the fossils were actually the remains of once-living sharks, now buried in rock. He was not the first to make this connection, but he did go on to define the fundamentals of stratigraphy, the branch of geology that studies rock layers (stratification).
Considering the question of how a shark tooth (or anything else) could become encased in rock, he decided that it must at one time have been surrounded by liquid while the layer below it was already rock. Known in stratigraphy as the law of superposition, this ultimately means that every layer of sedimentary rock must be younger than the layer below it, and this observation is the basis for all fossil dating today. Steno’s theory that the fossil record could be chronologically ordered by the rock layer in which each fossil is was found is fundamental to modern evolutionary theory.
As a follow-up, he also studied crystals and determined Steno’s Law of constancy of interfacial angles, which basically says that the angles between corresponding crystal faces are the same for the same mineral. Steno’s geological work was published 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.
In 1675 he was ordained into the priesthood, and in 1677 was made a bishop apostolic in the north of Germany. After 9 years of devoted ministry to the poor, he died in 1686.
Happy birthday, Nicolas – you are yet another great example of Christian faith informing ground-breaking scientific advances.