- Darwin’s Evolving Identity: Adventure, Ambition, and the Sin of Speculation by Alistair Sponsel
Alistair Sponsel’s Darwin’s Evolving Identity: Adventure, Ambition, and the Sin of Speculation is a substantial, eye-opening account of Charles Darwin’s development as a writer, and adds an important new chapter to our understanding of his early years as a voyager and geologist. Over the course of twelve trim chapters and a conclusion, it weaves a compelling narrative of Darwin’s extraordinary growth from an ambitious young student into the widely respected naturalist who shocked the Anglo-American academy with the publication of On the Origin of Species (1859). Sponsel’s careful sounding of print and manuscript archives, especially Darwin’s manuscripts and the papers of Charles Lyell, yields an impressive new account of the experiences, techniques, and discoveries that produced the most famous scientist of the Victorian era.
The first two (of four) parts of the study offer new insights into Darwin’s evolution. Part 1 puts unusual emphasis on Darwin’s time aboard the Beagle, detailing the studies of coral reefs that eventually produced his first major scientific finding and secured his [End Page 674] scientific renown. Sponsel provides an assiduous exploration of Darwin’s methods during the voyage, especially his innovative use of marine sounding equipment and his study of hydrology under the Beagle’s captain, Robert FitzRoy, in his effort to reconstruct the subsea structure of coral formations. The sounding lead, Sponsel explains, was uniquely important. Tipped with a wax cup that captured sediment, rock, plant matter, and coral from the seabed, it provided a method of indiscriminately sampling from a fixed point in the ocean, “helping Darwin to link geology, botany, and zoology” (41). Extensive reproductions of his notes, maps, and sketches show how Darwin used a methodical sampling of the seafloor to develop a portrait of the shape and composition of reefs and to describe their development in time. Demonstrating that corals only grow in a narrow band near the surface, but stand on formations of older, dead corals that sometimes descend hundreds of feet into the ocean, Darwin mounted a ground-breaking argument: such reefs prove that large areas of the Pacific seafloor are slowly sinking. This combination of series analysis and historical speculation looks forward to Darwin’s later analyses of species transformation. Part 2 details the role Lyell played in mentoring Darwin on his return, as he worked to develop and publish his coral studies while juggling a range of new social and professional obligations. Lyell’s private papers and other correspondence reveal him as even more important to Darwin’s early career than we have generally realized. Sponsel describes how Lyell stage-managed the debut of Darwin’s coral theory before the London Geological Society, quietly prepping Darwin and consulting on his paper, and then dramatically capitulating on those points that contradicted his own previous accounts. For the other auditors, the paper gained extraordinary credibility through Lyell’s dramatic reversal; for Lyell, it gave powerful new evidence for his wider geological system, at the expense of his pet speculations about island lagoons.
Parts 3 and 4 add important context to Darwin’s work on natural selection and his strategy in writing the Origin. Sponsel observes, for instance, that Darwin’s first efforts to speculate about species transformation came as a way to relieve the stress produced by his ongoing effort to finish and publish his 1842 monograph on corals, much as, to relieve the pressure of finishing the Origin, he would later turn to studying orchids. Darwin’s work on corals also established a pattern of radical speculation, in which “facts followed theories,” that would hold true for all of his major discoveries (221). Though described as Darwin’s “sin of speculation,” the study provides ample evidence of the evident joy with which Darwin set about building his various castles in the air before turning to the more arduous work of substantiating them (223).
Yet the major thesis of this...