The “principles of domestication are important for us,” Charles Darwin (1868b, 3) wrote in his Variation of Animals and Plants under Domestication, to illustrate “that the principle of Selection is all important” in producing evolutionary change (Fig. 8.1). The work of breeders, he explained, might be seen as “an experiment on a gigantic scale” that provided empirical support for his claims about analogous processes in nature. For instance, centuries of artificial selection of small heritable differences (variations) among domestic dogs had produced breeds as different as the bulldog, the greyhound, and the spaniel, each of them specialized to perform a specific task in the human household. In similar fashion, natural selection, by acting on the variations of wild animals and plants, had created the stunning diversity of the living world, in which every species was characterized by adaptations enabling it to survive and reproduce under the circumstances given by its natural surroundings.

Historians and philosophers of science agree that the analogy between artificial and natural selection was a vital element of Darwin’s argument in the Origin of Species (1859). Philosophers have argued that he deployed the analogy to show that natural selection was a vera causa, a true cause, in nature. Darwin proceeded by arguing, first, that domestic races can be produced by sustained selection of individual variations. He then claimed that both these elements, the variations as well as selection, are also present in nature and can in an analogous way, on a much longer time scale, produce new species (Waters 2003). There is some debate on how essential the analogy really was (Ruse 1975a; Gayon 1998). Darwin (1859, 457–59) himself claimed that, even without it, the available evidence spoke convincingly in favor of descent with modification. Nevertheless, he made good use of the analogy in his effort to structure the Origin as “one long argument,” as he called it.

In the distant future I see open fields for far more important researches…. Light will be thrown on the origin of man and his history” (Darwin 1859, 488). This statement, which appears in the concluding chapter to the Origin of Species, was Darwin’s only mention of human evolution in the entire book. He was well aware of the difficulties his biological propositions would encounter from believers in special creation and therefore thought it wise to leave the delicate question of human evolution aside for the time being. Darwin was nonetheless fully conscious that his theory would lead to important insights in this domain and would probably revolutionize the way we think about ourselves and our cultures. Enter social Darwinism.

The term social Darwinism, which came into fashion after 1940 (Hodgson 2004), has been used mainly to decry doctrines that justify some form of individual, social, or racial superiority through evolutionary principles with which Darwin’s theory is identified, such as the struggle for existence and natural selection. It has also been employed in reference to teleological explanations of the causes of human progress that often carry with them value judgments concerning the degree of civilization attained by various peoples. Yet many of the positions typically attached to social Darwinism do not correspond to this stereotypical description. Even among the main proponents of evolutionary theory in the nineteenth century – Darwin, Wallace, Huxley, and Spencer – there were important disagreements concerning the process of evolution in humans and its results. This article offers an examination of their claims, as well as some related and antagonistic viewpoints, in an effort to tease out the various and complex meanings of social Darwinism. By tuning the microscope to grasp the finer details, a surprisingly different picture from the one usually conveyed by this blanket term will emerge.

Alfred Russel Wallace (1823–1913) was an English naturalist who famously conceived of the principle of evolution by natural selection independently of Charles Darwin in 1858 (Fig. 19.1). Wallace is often incorrectly referred to as working class. In fact, he was the son of a solicitor with inherited property sufficient to generate an income of £500 per annum (Wallace 1905,1:7). Thus, according to the conventions of the day, Wallace’s father was a gentleman. The family’s financial circumstances, however, declined so the Wallace family moved from London to a village near Usk, on the Welsh borders, where Wallace was born in Kensington Cottage on 8 January 1823. As far as Wallace could later remember, the family kept one servant. Wallace is also sometimes described as Welsh. This is also incorrect. His parents were English. As a small boy in Usk, Wallace could remember, because of his blonde hair, that “I was generally spoken of among the Welsh-speaking country people as the little Saxon” (1:29). Wallace also referred to himself as “English” or an “English naturalist” many times in his publications (C. S. Smith 1998).

When Wallace was six years old, the family moved to Hertford, north of London, where he lived until he was fourteen. Here Wallace attended Hertford Grammar School, where he followed a classical education, not unlike Darwin’s at Shrewsbury School, including Latin grammar, classical geography, and “some Euclid and algebra” (Wallace 1905). During his last year in Hertford, the family’s finances further declined so that Wallace was obliged to tutor other students to pay his fees. Wallace was deeply conscious of this fall in status before his peers. He later described the shame of this and other cost-saving measures imposed by his parents as a “cruel disgrace,” “exceedingly distasteful,” and perhaps “the severest punishment I ever endured” (1:58). Wallace left school in March 1837 aged fourteen, just as Darwin was becoming a transmutationist.

When Charles Darwin wrote in the Origin of Species (1859, 482) that he looked to the “young and rising naturalists” to heed the message of his book, he likely had in mind individuals like Ernst Haeckel (1834–1919), who responded warmly to the invitation (Haeckel 1862, 1:231–32n) (Fig. 28.1). Haeckel became part of the vanguard of young scientists who plowed through the yielding turf to plant the seed of Darwinism deep into the intellectual soil of Germany. As Haeckel would later observe, the seed flourished in extremely favorable ground. The German mind, he would write (1868), was predisposed to adopt the new theory. The great philosopher Immanuel Kant (1724–1804), for instance, was on the verge of accepting a transmutational view in his Third Critique ([1790] 1957, 538–39), though he stepped gingerly back from the temptation. Johann Wolfgang von Goethe (1749–1832), about the same time, dallied with transmutational ideas, or at least Haeckel would convince Darwin that the Englishman had an illustrious predecessor. Jean-Baptiste de Lamarck’s (1744–1829) conceptions had taken hold among several major German thinkers in the first few decades of the nineteenth century in a way they had not in England and France. Among those ready to declare themselves for the new dispensation was Rudolf Virchow (1821–1902), Haeckel’s teacher at Würzburg – though this very political scientist would prove Haeckel’s nemesis later in the century. So Haeckel’s estimate of the ripeness of German thought was not off the mark. Darwinism took hold in the newly unified land, though not without some struggle; at last, it became the dominant view in the biological sciences. But with its success, did it also foster the malign racist ideology that transfixed Adolf Hitler (1889–1945)?

What counts as an alternative to the Darwinian view of biological origins depends on what one takes Darwinism to be. To advocates of “special creation,” Darwinism refers to its author’s claim that all organisms evolved from a single common ancestor. Among evolutionists themselves, however, Darwinism refers to natural selection, Darwin’s distinctive mechanism for explaining species transformation and common descent. Creationist challenges are not our topic. Challenges to natural selection as causally explaining it are.

As it happened, natural selection inserted itself into an already lively debate about evolutionary mechanisms (Desmond 1989; Secord 2000). Darwin’s was a powerful idea, but not powerful enough to knock out all of its rivals, which have reasserted themselves whenever a version of Darwinism that has organized evolutionary research for a time – and there have been several – runs into trouble. Trouble can come from new empirical discoveries, from the discrediting of false claims or assumptions on which Darwinians had relied, or from research methods that prove flawed.

Darwinism’s currently established but aging version, the modern evolutionary synthesis, has been facing challenges of all three sorts since the 1980s. The modern synthesis was first articulated just before and during World War II on the basis of technical work done earlier (Dobzhansky 1937 ; J. S. Huxley 1942 ; Mayr 1942 ; Simpson 1944). It claimed to unify all biological fields by integrating natural selection with genetics, about which neither Darwin nor nineteenth-century Darwinians knew anything.

Ecological genetics is a field of biology at the intersection of genetics, ecology, and evolution that emerged during the early 1930s in Britain and is particularly associated with the research of E. B. Ford, H. B. D. Kettlewell, A. J. Cain, P. M. Sheppard, C. A. Clarke, and their numerous intellectual descendants (Fig. 35.1). Ford (1964, xi), the self-identified inventor of the field, defined it as “the experimental study of evolution and adaptation, carried out by means of combined field-work and laboratory genetics.” It is devoted to the study of the genetics of adaptations, that is, traits affecting survival and reproduction, and the ecological processes that affect the distribution and evolution of these genes in natural populations.

Connection to Darwin

There is an obvious sense in which Charles Darwin is the progenitor of the modern biological field known as ecological genetics. Darwin’s Origin of Species drew attention to the ubiquitous presence of heritable variation in nature, the power of natural selection as an explanatory agent in accounting for the origin and maintenance of biological adaptations, and the importance of studying living organisms by means of biogeographical patterns of distribution. Darwin was also an early and important pioneer and advocate of the systematic use of experimental methods in the study of natural history. Ecological geneticists certainly see themselves as intellectual descendants of Darwin in that they often position their work as providing experimental confirmation of his theory of evolution by natural selection.

The publication of Darwin’sOn the Origin of Species (1859) sparked little interest among Jews during the 1860s. When it was discussed, most rabbis opposed Darwin, citing human intellectual and moral uniqueness, the absence of observed speciation, and the variety of technical issues debated by scientists. Some rabbis maintained that science alone would decide the truth of Darwin’s theory; science and religion addressed different human concerns and different aspects of reality. This position had roots in traditional Judaism and philosophical trends that shaped nineteenth-century German Jewish thought (Faur 1997; Swetlitz 1999; Cantor 2005; Efron 2007).

Attention increased significantly in the 1870s. The publication of Darwin’s The Descent of Man (1871) and publicity given to scientists proclaiming the materialist implications of evolution were important factors. Rabbis discussed the implications of evolution for belief in God and conceptions of humanity and produced a diversity of views, ranging from outright rejection to enthusiastic embrace and all flavors in between. Moreover, diversity existed within Jewish communities, as well as between the emerging Reform, Conservative, and Orthodox movements. The resulting tensions and debates about the nature of Judaism helped to shape discussions about evolution.

In the mid-1820s, Charles Darwin was in medical school at the University of Edinburgh. There he met the evolutionist Robert Grant. Grant was interested in zoophytes, organisms that were considered plantlike animals. He and others hoped these organisms might help bridge the gap between the two kingdoms. Darwin accompanied Grant on collecting trips to the Firth of Forth, and it was through this work that he had his first brush with scientific scholarship. Darwin delivered a short report to the Plinian Society, a natural history club, on his observations of the “ova” of Flustra, a seaweed-like aquatic invertebrate.

A few years later, while aboard the Beagle, Darwin’s interest in zoophytes continued. In his account of the voyage, he offered the following reflective description of one of these species, Virgularia patagonica:

A good deal of Charles Darwin’s endeavors were bound up with geography. First and foremost he followed in the steps of scientific geographer-travelers like Alexander von Humboldt when he embarked on his five-year round-the-world voyage on the Beagle in 1831. Later in life he recalled that during his final year at Cambridge he had “read with care and profound interest Humboldt’s Personal Narrative,” and he kept it constantly by his side throughout the Beagle mission, not just for its landscape evocations but for its scientific insights on subjects as diverse as polished syenitic rocks in the Orinoco, atmospheric conditions in the tropics, crocodile hibernation, connections between earthquakes and weather conditions, and miasmas in the torrid zone (Darwin 1958b, 67; Egerton 1970) (Fig. 44.1). Not surprisingly, shortly after his return home, he was elected to Fellowship of the Royal Geographical Society in 1838, having been nominated by the British diplomat, traveler, and geologist, Woodbine Parish. J. Stuart Wortley, agriculturalist and politician, and the geologist Charles Lyell, added their signatures in support (Fig. 44.2). Later in 1840 he served for a year on the society’s council.

Beyond the external fabric of Darwin’s life and institutional affiliations, of course, Darwin, Darwinism, and geography have intersected in numerous other significant ways. Here I propose to take three cuts at the subject: I turn first to the role of geography in Darwin’s thinking and experience; then I trace something of the influence Darwin exerted on the geographical tradition; and finally, as an experiment with Darwinian resonance, I suggest that Darwinism itself might well be considered an intellectual species that endured different fortunes in different cultural environments and thus displayed its own geographical distribution.

How did life emerge on the ancient earth? Since the middle of the twentieth century, scientists have applied a plethora of experimental and theoretical approaches in an attempt to answer this question. Yet it is still considered one of the most challenging questions facing science today. Holding different theories and favoring different scenarios, all researchers, however, are united in a conviction that the organization of the first living systems out of chemical building blocks was a natural process. Moreover, scientists have no doubt that it was an evolutionary process.

The evolutionary view presents a radical departure from the previous conception of the origin of life held by both laypersons and naturalists for most of human history. On the basis of everyday experience, people were obviously aware that various organisms were being sexually generated from their parents. Since the rise of monotheistic religions, the general belief was that God originally created the “founding fathers” of the major types of living beings that kept perpetuating their fixed kind generation after generation. In parallel, people were also convinced that plants and many animals repeatedly arise under the influence of moisture and heat not from parents but rather from mud, tree bark, excrement, and decaying plants and animal matter. This belief in “spontaneous generation” accompanied humanity from antiquity till the modern age, having been sustained in different epochs by both religious and materialistic lines of reasoning (Farley 1977; Fry 2000).

Darwin’s Origin of Species(1859) argues for two big ideas, both metaphorically expressed: the tree of life and natural selection. New species descend from earlier, ancestral species; and these lines of descent with divergent modifications branch and rebranch, like the branches on a tree. So, if every line traces to one first species, all life forms one tree. Natural selection has been the main cause of these changes. By selective breeding, humans make, in a domesticated species, varieties fitted for different ends: heavy horses for plowing, fast ones for racing. In the wild, over eons, natural selective breeding due to the struggle for existence works unlimited changes in branching lines of adaptive, divergent descents, from fish ancestors fitted for swimming to bird descendants fitted for flying and mammals for running.

Darwin first had these ideas more than twenty years before publishing them in the Origin. In October 1836, the Beagle voyage ended. In July 1837, he opened his private Notebook B with a comprehensive account of the course and causes of life’s changes, including a first version of his tree of life. He has the idea of natural selection late in 1838, in Notebook E. The ideas may look like instant insights; but the story is not so simple. Any short telling of the origins of the Origin commits misleading omissions and condensations. However, even this very short one can counter two contrasting demands: from rationalists hoping for an edifying tale of universal methodological principles consistently yielding successful solutions to certain given problems specifiable in advance; and from romantics yearning for an epic saga of individual genius bringing imagination and intuition to transcendent reconfigurations of experience, man, nature, and so the whole world. (For documentation of what is said here about Darwin’s early theorizing, and for references to the secondary literature, see M. J. S. Hodge 2009b; for the texts of the notebooks, see Barrett et al. 1987. Becquemont 2009 is an important recent study.)

Bumblebees, insisted a writer signing himself Ruricola (1841) in the Gardeners’ Chronicle, wrought terrible damage on bean crops by rapaciously drilling holes in the bean flowers in search of nectar. Ruricola advised gardeners to protect their crops from these costly acts of vandalism by eradicating bees’ nests as soon as bean flowers bloomed. Charles Darwin (1841) responded four weeks later with a vigorous, if qualified, defense of the bees, “these industrious, happy-looking creatures.” The boring did little material damage to the flower, he insisted. The bees’ activity perhaps did the plants an injury nonetheless, but in a more indirect, perfidious way than Ruricola imagined. The plants offered nectar to the bees in exchange for transferring pollen from flower to flower. The bees, by lapping up their reward without earning it by brushing over the reproductive parts of the flower, were in effect “picking pockets.”

This short communication, written in the summer of 1841, was Darwin’s first public remarks on a defining passion of his life. Over the next forty years he published numerous articles and books on the complex relationship between the reproductive organization of flowering plants and their environment. After the publication of the Origin of Species in 1859 he promoted evolution as the unifying principle behind his botanical breakthroughs. The German botanist Hermann Müller (1879, 2), one of many naturalists who built a career advancing Darwin’s approach, declared that this marriage of evolution and botany provided “the key to the solution of the riddle of the flower.” This solution was not, of course, on offer in his response to Ruricola. But in this modest communication, so seemingly inconsequential when laid next to the panoramic generalizations of the Origin, we discover the epitome of Darwin’s scientific character.

Much of the physical evidence for evolution comes from paleontology. Before the arrival of molecular genetics, fossils were just about the only evidence available that evolution had actually taken place, and some individual specimens have come to have iconic status for their role in confirming predictions of evolutionary theory (Archaeopteryx, Lucy, Tiktaalik, etc.) (Fig. 43.1 and Plate XXXIII). Darwin, of course, was very much interested in the fossil record, and indeed his geological and paleontological observations both during his Beagle voyage and afterward played a formative role in shaping his ideas about evolution (see Brinkman, Essay 4 in this volume). However, Darwin also worried a great deal about how the fossil evidence supported his theory of evolution; in Origin, he set aside an entire chapter to discuss the “imperfections” of the geological record, and in general it is fair to say he regarded the fossil record as a disappointment at best and a serious liability at worst. Darwin’s assessment of the fossil record, then, cast a long shadow over the subsequent development of the professional discipline of paleontology.

Up until the time of the modern evolutionary synthesis in the 1940s, paleontology was generally regarded by biologists as a discipline suited mostly to the collection and description of empirical evidence – fossils – but not one that could make unique contributions to our understanding of the patterns and processes of evolution. In the mid-twentieth century, however, some paleontologists began to resist this “descriptive” label for their discipline and to promote an approach to the history of life and the fossil record that was explicitly theoretical and evolutionary. By the 1970s, this approach came to be known as “paleobiology,” and today it is one of the central viewpoints in the discipline.

Darwin’s attitude to religion can be summarized as thoughtful but detached. There is no evidence that he ever had any strong religious feelings or a sudden crisis of faith. Although he gradually lost any belief in Christianity “as a divine revelation,” he described himself variously as a theist or agnostic but never as an atheist, drawing a careful distinction between the neutral “unbelief,” or lack of belief, of agnosticism and the positive “disbelief” of atheism. Toward the end of his life, Darwin wrote that disbelief in “Christianity as a divine revelation” had crept over him at a very slow rate “but was at last complete.” The rate was so slow that he felt “no distress,” and he had “never since doubted even for a single second” that his conclusion was “correct” (Recollections). Emma Darwin and Francis Darwin both referred to the importance to Darwin of the distinction between disbelief and unbelief in letters discussing publication of the Recollections written after his death; Emma Darwin considered that the use of the word “correct” was misleading and that Darwin intended to convey that he himself never “altered his opinion” rather than that he thought the position untenable (CUL DAR 210.8: 42 and 219.1: 179).

Darwin accepted that others found it possible to believe both in evolution and in a deity, and he respected that position. He had a profound respect for the views of others and was generally reticent about his own, both from a natural aversion to causing unnecessary distress and, more pragmatically, because he regarded conflict as counterproductive. Typical is this response to an inquiry as to whether natural selection was compatible with belief in a personal God: “My opinion is not worth more than that of any other man who has thought on such subjects … I thank you for your Judgement & honour you for it, that theology & science should each run its own course & that in the present case I am not responsible if their meeting point should still be far off” (Darwin 1985–, 14:423, letter to M. E. Boole, 14 December 1866).

Charting the course of evolutionism in Britain can be seen as an exercise in trying to understand the emergence of and response to what became known as “Darwinism.” Thomas Henry Huxley coined the term and tried to control how it was used – he was, of course, known as “Darwin’s bulldog” because of his aggressive support for the theory. But Darwinism certainly didn’t entail complete acceptance of the program outlined in the Origin of Species, because even Huxley would not have been a Darwinian on those terms (Fig. 26.1). To understand what was going on in the context of the time, we must be aware that the meaning of the term “Darwinism” has also changed over time. In the modern world it usually refers to the theory of evolution by natural selection. But in the late nineteenth century many evolutionists who did not believe that natural selection was the main mechanism of evolution called themselves “Darwinians.” The true value of the selection theory was recognized only in the twentieth century, so the contemporary reception of Darwin’s theory has to be understood in terms of a much broader debate over what evolutionism entailed.

To many ordinary people, Darwin simply became a symbol or figurehead for a generalized evolutionary philosophy, probably entailing notions of progress and the struggle for existence. In his later life, his face became familiar to all thanks to the publication of portraits and caricatures – often emphasizing certain apelike aspects of his features – published in popular magazines (Browne 2002). Even at this level there were ambiguities, though. Our vision of the initial debate over the Origin of Species has been shaped by the negative reaction of conservative religious thinkers and by Huxley’s strident anticlericalism, both fueling the claim that evolution and Christianity are incompatible. But because evolution was popularly supposed to entail progress, it was accepted by many liberal clergymen, whose views were thus not so far removed from those of the less aggressive secularists.

In the Origin, Darwin explained that he used the term “chance” variation only to signify his (and others’) ignorance of the process by which new traits arise. In an enthusiastic review of the book, Asa Gray suggested a friendly amendment: that as long as the cause of variation was unknown, it should be attributed to God. Gray’s idea was that God had arranged for particular traits to arise in particular lineages at particular times, to be subsequently accumulated by natural selection. Before Gray’s suggestion, Darwin had hoped that evolution by natural selection might be viewed simply as God’s way of making new species. But in reflecting on Gray’s suggestion, Darwin realized that reconciling evolution by natural selection with any sort of conventional theology was going to be much more difficult than he had imagined (Figs. 16.1 and 16.2).

On the one hand, unless God arranged for just the right traits to arise in just the right lineages at just the right times (as Gray recommended), then evolution by natural selection would not guarantee the existence of any particular evolutionary outcomes, humans included. And surely humans were the end of Creation, no matter what the means. On the other hand, this way of making species required an awful lot of trouble on God’s part. Evolution by natural selection initially seemed like such a simple way for God to proceed: he only had to establish a set of laws (to govern population growth, inheritance, etc.) and then sit back and wait for species to make themselves, rather than creating each one separately. But the degree of divine guidance that Gray suggested – presumably for each and every species, not just humans – was as much or more trouble than special creation. Indeed, it was just a complicated form of special creation.

In his Autobiography, written toward the end of his life, Darwin (1958a, 140) wrote that the Origin consists of “one long argument.” Let us start there. The argument came in three main parts. In a letter written a year or two after the Origin was first published, Darwin outlined his strategy (Fig. 9.1).

Note Darwin’s use of the term “vera causa.” Verae causae, or “true causes,” were things insisted upon by Isaac Newton, a demand endorsed by those writing on science in Britain in the 1830s. This was just the time when Darwin was thinking creatively about evolution, and it is clear that the young scientist took the exhortation to heart. He wanted to produce an evolutionary theory that would live up to the standards of the best science, meaning the best Newtonian science.

We owe to Charles Darwin and Alfred Russel Wallace not the discovery of evolution but the creation of a powerful causal explanation for the small and large facts about nature that fascinate us as children and as adults. The principle of natural selection provides at least part of an explanation for a myriad of traits ranging from the shape of an orchid blossom to the visual acuity of a hawk’s eye. Darwin’s 1859 presentation of the principle in On the Origin of Species is a synthesis of observation and explanation that should amaze any curious reader. Wallace’s (1870a) discovery of natural selection is no less amazing, especially given the more difficult circumstances that surrounded his work (see Berry 2002). Their discovery is a human achievement of the first order, which should transcend political and social divisions. But it is best to understand the world as an “is” and not as a “should.” Most people believe some sort of divine explanation for the kind of facts about nature that I just mentioned; if they are aware of Darwin’s and Wallace’s discovery, they dismiss it as false. Few, if any, of these people will read this essay. You, the reader, are likely aware of the truth and importance of Darwin’s and Wallace’s discovery or are open to their discovery being correct. Even so, in order to understand how the testing of evolution has evolved, it is useful to examine the nature of Darwin’s and Wallace’s achievement, especially because it is often misunderstood even by those who recognize that it is correct.

In this context, it is worth comparing the “before” and the “after” of their discovery. To understand the “before,” it is most meaningful to consider claims about nature that at least appear to be based on substantial assemblages of facts (as opposed to claims as to the “fact” of, say, divine creation that were simply appeals to faith and referenced few, if any, facts). With this restriction, all claims we consider are arguably science, inasmuch as there is marshaling of evidence (as opposed to just an appeal to belief). Given this restriction, one finds a wide variety of claims that range from the claim that the facts are explained by divine creation (Paley 1802) to those that invoke natural causes.

Darwin had been elaborating his theory of evolution since 1837 and was consciously working on his “Big species book” at least since 1854, when he had to write On the Origin of Species within little more than one year. Consequently, he bluntly presents it as an abstract, with all its contingencies. We usually see “abstract” as a positive quality, for it led Darwin to keep a clear line of argumentation; but he certainly perceived it as a fault. Having amassed hundreds of pages of material, Darwin at first decided to publish his book, only to avoid being forestalled by A. R. Wallace, under the title “the abstract of an essay on the origin of species and varieties through natural selection.” In the first edition of the Origin, Darwin refers constantly to a “longer work” that he was planning to complete. But this was eventually pushed aside by other projects and Darwin’s involvement in the debates launched by the Origin. Instead, Darwin dedicated a lot of time to a careful reworking of his 1859 text, which makes the Origin a book with different versions.

During Darwin’s own life, no less than six successive editions were published by John Murray. In this essay, I follow Morse Peckham’s system of reference: [a] for the first edition (November 1859); [b] for the second (January 1860); [c] for the third (April 1861); [d] for the fourth (December 1866); [e] for the fifth (August 1869); [f] for the sixth (February 1872). This evolution of the Origin was the textual process through which 75 percent of the book underwent modifications, while its global length increased by one-third. All those changes are documented in Peckham’s Variorum text – a book that changed our view of the Origin, although it is an unreadable maze of additions and corrections (Peckham 1959, noted hereafter as Var). Almost everything changed during the long life of the Origin, including its birthdate (from “October 1st, 1859” in [a] to “November 24th” in [d]) and its title (the initial “On” is dropped in [f]).

A teleological explanation is one in which some property, process or entity is said to exist or be taking place for the sake of a certain result or consequence. For example, after returning from a run, someone might ask, “Why did you go for a run?” If you answer, “In order to keep fit,” you are explaining your run by pointing to a consequence of running, keeping fit. Or, someone might ask, “Why do hawks and owls have sharp, hooked beaks and talons?” If one answers, “Those sharp talons and hooked beaks are for the sake of capturing and eating their prey,” these traits are explained by reference to the (valuable) consequences for the organism of having those traits. It is not just that they have these traits and these traits serve a valuable function for these birds – they have these traits because they serve this valuable function.

Teleological explanations have played a central role throughout the history of the life sciences. Biological textbooks invariably suggest that teleological explanations were expunged from the physical sciences in the seventeenth century and finally, thanks to Charles Darwin, from the biological sciences in the nineteenth. And yet the same textbooks often explain adaptations by reference to natural selection in language that sounds suspiciously teleological. “That color pattern is present in the males of that population of fish because it increases their attractiveness to female mates without increasing their visibility to predators.”