It is ironic that Alfred Russel Wallace’s finest moment—his 1858 discovery of natural selection—has in many ways compromised his place in history, condemning him forever to footnotes in textbooks. It has resulted in his always being coupled with Darwin, but as a junior partner: he is destined always to play Watson to Darwin’s Holmes. One of the many interesting features of the Wallace story, then, is how and why, relative at least to Darwin’s, his star has dimmed so precipitously. After all, he was one of the true superstars of Victorian science; he was the codiscoverer of natural...

THIS BOOK IS OFFERED as one biologist’s apologia for Alfred Russel Wallace (1823–1913), autodidact explorer-naturalist whose epic journeys, geographical and intellectual, contributed profoundly to revolutionary new understandings of earth history and of the life upon earth in the mid- to late nineteenth century. It is occasioned by the Wallace Centennial and an opportunity to pore over Wallace’s never-before-published “Species Notebook,” the most important field notebook from his Southeast Asian explorations. I had the privilege to transcribe, annotate, and analyze this notebook in a work published by Harvard University Press under the titleOn the Organic Law of Change: A...

ALFRED RUSSEL WALLACEʹS road to accepting the idea of transmutation of species was short: one reading ofVestiges of the Natural History of Creationin 1845 was sufficient to convince him of the essential correctness of the idea. His journey to deep insight into the phenomenon, however—his intellectual journey adducing the evidence in support of the idea and figuring out the mechanism behind it—was rather longer, but not exceedingly so: his Sarawak Law paper was published just ten years later, and the Ternate essay announcing his discovery of the mechanism of species change three years after that. When...

HOW DO WE KNOW when we are on the right track in elucidating a scientific principle or explaining some natural phenomenon or observation? Although scientific methods and conventions used today have their roots in the empirical sciences of astronomy and physics of the seventeenth century, the self-conscious study of science as a process—ofhowwe study the natural world—had only begun to be formalized in the nineteenth century. In Britain the leading natural philosophers of that century charting the course for what we now call scientific methodology include the English astronomer Sir John Herschel (1791–1872), in his...

WALLACEʹS PAPERS, notably but not exclusively the Sarawak Law and Ternate papers, show him assembling the key building blocks of a cogent argument for species change: (1) evidence supporting the contention that transmutation occurs, (2) a model for how this occurs in the context of Lyellian change in earth and climate, and (3) a plausible natural mechanism for species change. The Species Notebook fills in many “behind the papers” details about Wallace’s thinking, in much the same way that the Transmutation Notebooks do for Darwin. This chapter explores the commonalities and differences in the sorts of information drawn upon by...

WALLACE AND DARWIN were hard at work through the 1850s, each pursuing an impressive range of topics. Extracts from a steady stream of letters chronicling Wallace’s observations and experiences afield in Amazonia and then Southeast Asia were duly published by Samuel Stevens, punctuated by a series of scientific papers on a multitude of topics: from entomology and ornithology to geology, geography, and ethnology. No slouch either, Darwin pursued mostly private investigations into such diverse subjects as seed dispersal, longevity, and viability in seawater, hybridization, fertilization by bees, and insectivorous plants—all undertaken with an eye toward gathering evidence for his...

IT HAS LONG been appreciated by scholars that Wallace’s and Darwin’s concepts of natural selection differed in important ways (e.g., Bowler 1976; Kottler 1985; Bulmer 2005), though at the time Darwin, Lyell, and Hooker believed them to be “the very same ingenious theory.” In the main, the similarity that caused Darwin so much angst lies in the general formulation of natural selection. He and Wallace came to understand the deductive core mechanism at the heart of the evolutionary process: the idea of abundant, undirected, and heritable variation, tremendous population growth potential giving rise to a struggle for existence such that...

IN CHAPTER 4 I compared the key evolutionary ideas of Wallace and Darwin as reflected in their respective writings as of the late 1850s, alluding only briefly to the circumstances surrounding the receipt and publication by Darwin of Wallace’s Ternate essay. In this chapter I explore this issue more deeply, offering a brief guide to the controversy over the timing of the arrival of Wallace’s letter and manuscript, and the question of the use (or not) by Darwin of the ideas it contained. Previously I described Darwin’s apparent surprise and dismay over the “striking coincidence” of Wallace’s formulation. “If Wallace...

WALLACEʹS PRAISE of Darwin’s achievement on his reading ofOn the Origin of Specieswas sincere: in letters to family and friends he applauded the elder naturalist’s efforts—Darwin’s labors of twenty years during which he fleshed out the theory, following out the nuances and intricacies of evidence for transmutation and the action of natural selection. Wallace concluded one lengthy encomium for Darwin declaring: “the force of admiration can no further go!!!” But while Wallace lauded Darwin and deferred to his priority, he never shied away from disagreeing with Darwin over aspects of the evolutionary process. For several matters of...