Free Hen’s Teeth and Horse’s Toes by Stephen Jay Gould

regularities underlying the uniqueness of each species and interaction, while treasuring that irreducible uniqueness and describing all its glory. Notions of science must bend (and expand) to accommodate life. The art of the soluble, Peter Medawar’s definition of science, must not become shortsighted, for life is long.

2 | Personalities

5 | The Titular Bishop of Titiopolis
    MODERN GEOLOGY BEGAN , or so the usual story goes, with the publication of a book so oddly named that it almost surpasses the peculiarity of the title later assumed by its author, Nicolaus Steno, a Dane by birth and a Catholic convert who became Titular Bishop of Titiopolis (in partibus infidelium) in 1677. (Titular bishops “preside” over areas in pagan hands and therefore unavailable for actual residence—in the realm of infidels, as the Latin subtitle proclaims. The old bishopric of Titiopolis is now part of Turkey.) As his real job, dangerous enough in Protestant lands, Steno ministered to the scattered Catholic remnants of northern Germany, Norway, and Denmark.
    The book, published in 1669, bears a title considered “almost unintelligible” by its chief translator from the original Latin. It is called De solido intra solidum naturaliter contento dissertationis prodromus , or Prodromus to a dissertation on a solid body naturally contained within a solid . A prodromus is an introductory discourse, but Steno never wrote the promised dissertation because his religious interests, following his conversion in 1667 and his ordination in 1675, led him to abandon his distinguished career as a medical anatomist and, by fortuitous introduction at the very end of his scientific work, a geologist.
    Why a solid within a solid? And what can such a cryptic phrase have to do with the origin of modern geology? Posing a problem in a startling and novel way is the virtual prerequisite of great science. Steno’s genius lay in recognizing that a solution to the general problem of how solid bodies get inside other solids might provide a criterion for unraveling the earth’s structure and history. But Steno did not formulate his problem by rational deduction from his armchair. As so often happens in a human world, he drifted toward it after an accidental beginning.
    Like many anatomists, Steno became interested in the resemblances of humans with other animals. He decided to dissect sharks and made some important discoveries. He demonstrated, for example, that the tight coils of the spiral intestine yielded the same total length (within a more confined space) as the meandering intestine of mammals. In October 1666, during Newton’s great year, or annus mirabilis , and a month after London burned, Steno received for study the head of a giant shark caught at the city whose English name, Leghorn, is as peculiar as Steno’s two titles. (The name refers neither to limbs nor musical instruments, but represents a poor English rendering of the old spelling, Ligorno, for the town now called Livorno in Italian.) Steno, like so many intellectuals, was working at the nearby city of Florence under the patronage of Ferdinand II, the Medici grand duke. In examining the teeth of his quarry, Steno recognized that he had accidentally bought into one of the major scientific debates of his age, the origin of glossipetrae , or tongue stones.
    These fossil sharks’ teeth could be collected by the barrel, especially in Malta. In twentieth-century terms, their origin cannot be doubted. They are identical with the teeth of modern sharks in outward form, detailed structure, and chemical composition—therefore they cannot be anything but sharks’ teeth.
    Yet the identity in form that makes us so certain led to another potential interpretation in Steno’s time—for God, the author of all things, often created with striking similarity in different realms to display the order of his thoughts and the glorious harmony of his world. If he had made a world with seven planets (sun, moon, and