If evolution is the non-miraculous, scientific explanation for the origin of species, it will come as no surprise that the original problem that led to the development of evolutionary theory was the search for natural (secondary) causes to explain the origin of the modern biota: the living species of animals, plants, and fungi. It was a simple, hard-to-ignore fact that, as you climb vertical stacks of fossiliferous rocks, the fossils you find become progressively more modern in aspect, until, near the top of the sequence, in the youngest sediments, species still alive in the modern fauna begin to make their appearance.
Years ago, as a fledgling paleontologist, I used to wonder how it could possibly have been that, according to the historians of geology and biology I had read, early paleontologists and naturalists had evidently failed, if not to see, then at least to think seriously about, this pattern and what it might mean for an understanding of causal pathways leading to the advent of the modern fauna.
As it turns out, this general pattern of the progressive modernization of the fauna was indeed recognized by a diverse array of early natural philosophers, including some who remained opposed to the general idea of evolution (or at least Jean-Baptiste Lamarck’s version of transmutation: Georges Cuvier, for example); others among the earliest to embrace transmutation (for instance, Robert Jameson); and the famous transmutational waffler (but skilled geologist and ecologist) Charles Lyell. As already noted, historians have tended to gloss over these early discussions of progressivism (or successionalism), trapped as most have been into thinking that evolution is fundamentally, perhaps even solely, a process of adaptive modification of organismal phenotypic characteristics.
THE OLD SHELL GAME
The fossil record of vertebrates has always held the most fascination for naturalist and layman alike, with the by-now dense fossil record of human evolution the secular equivalent of the Holy Grail. But it was the immensely denser, richer, and easier to find and to collect fossil remains of marine invertebrates in the younger sediments, typically distributed near the margins of continents, that led to the first empirical and analytical explorations of what might be the patterns and natural, non-miraculous causes underlying the appearance of new species, up to and including the advent of the modern fauna.
Earlier savants had advocated natural causal explanations for the history and diversity of life. Most famous, perhaps, was Charles Darwin’s own grandfather Erasmus Darwin, who deserves recognition in his own right, and not just for the more successful accomplishments of his grandson. But as grandson Charles was later to complain in Autobiography, Erasmus’s work was rather high on speculation and rather low on empirical evidence.
Systematics, the recognition and classification of natural groups of what came to be called “allied forms” by naturalists long before most of them subscribed to any notion of transmutation, was also a necessary, if not a sufficient, precursor to the emergence of what we would recognize today as modern evolutionary theory.
The Frenchman Jean-Baptiste Lamarck and the Italian Giambattista Brocchi shared not only the same first name, but far more importantly, the distinction of being the first to develop natural causal explanations of the origins of modern species that were both empirically and phylogenetically based.
Both Lamarck and Brocchi attempted to trace lineages among closely similar species considered to be members of the same natural group, especially among species within a genus. They were applying a phylogenetic perspective to the search for causal explanations of the origin of modern species. Nor was this insistence on focusing the discourse on closely similar, apparently allied species necessarily a no-brainer. For example, Charles Lyell, in the second volume of Principles of Geology (1832), estimated that species originate, and become extinct, roughly at the rate of one per year, measured in all the ecosystems worldwide. But his gaze was thoroughly and steadfastly non-phylogenetic. Believing that, for example, a new species of carnivore could not appear until the proper prey species had appeared, Lyell’s notions of species origination and extinction were distinctly ecological, rather than phylogenetic, in character. Lyell’s book was largely an extended refutation of Lamarck’s ideas, and against the very idea of transmutation, though he did pirouette on the fence in one long paragraph, in which he acknowledged the pattern of the progressive “younging” of species as one approaches modern times in the fossil record.
Both Lamarck and Brocchi developed their earliest ideas through studies on Cenozoic (roughly 65 million years ago down to the youngest sediments) fossil mollusks. The advent of the modern fauna, as seen especially as the replacement of species within genera in marine mollusks, was the crucible in which the rudiments of evolutionary theory were born. And from its very inception, evolutionary process theory was divided into two camps, based on strikingly different claims on the very nature of patterns of stability and change of species in the fossil record: Lamarck and Brocchi made radically different claims about empirical patterns they saw revealed by their fossils.
Lamarck saw utter continuity and intergradation in time and space: all species are destined to change slowly into descendants through time, and, when the data were complete, would also be seen to intergrade geographically into other species of the same genus.
In sharp contrast, Brocchi regarded species as discrete and stable entities. Species have births, histories with little or no change, and eventually, inevitably, deaths programmed into them like the deaths of individual organisms. Old species do not change into descendants. Rather, they give birth to new, descendant species, just as organisms give birth to offspring.
It is one of the greatest ironies in the history of biology that Darwin, so often seen as the polar opposite of Lamarck in terms of the mechanisms they put forward to explain transmutation (natural selection versus the “inheritance of acquired characters”), came to insist that Lamarck was right when it comes to the patterns of evolution: species are bound to change through time, intergrading imperceptibly into descendants. While the fossil record seems to say the opposite, Darwin decided that the fossil record itself was at fault. That species do not seem to intergrade laterally, he decided, was that intermediate populations, subspecies, and closely related species had succumbed to extinction. The pattern of evolution Darwin left us with was Lamarckian—though his initial scientific thinking in evolution was pure Brocchian transmutation.
In the terminology I used in the late 1970s, then, Lamarck was thinking “transformationally,” while Brocchi was thinking “taxically.” The dichotomy was there from the inception. What follows is a bit more detail on Lamarck’s and Brocchi’s seminal views, and the critical demonstration that young Darwin was thoroughly familiar with both sets of ideas through his training in the 1820s—especially as a medical student in Edinburgh from 1825 to 1827, but also through his experiences at Cambridge in the years leading up to the Beagle voyage.
LAMARCKIAN TRANSMUTATION
Containing the earliest significant arguments proposing transmutation based on perceived temporal sequences of closely related species, Jean-Baptiste Lamarck’s writings in the early nineteenth century stand firm as the earliest empirical, transmutational scientific work critical to the emergence of evolutionary biology as we know it today (figure 1.1). And though Lamarck is perhaps best remembered for the evolutionary ideas expressed in Philosophie zoologique (1809), his first important statements on the subject appear in the short introductory section on fossil mollusks in Systême des animaux sans vertèbres (1801:403–411).
As becomes clear as we trace the influence of both Jean-Baptiste Lamarck and Giambattista Brocchi, primarily if not solely among the medically trained savants in Edinburgh in the 1810s and 1820s, both Lamarck’s admirers and his detractors often mocked him for his exaggerated claims—not over process, but instead over his actual, putatively empirical, claims about the patterns of biological history he claimed to be generally true.
FIGURE 1.1 James Hopwood Sr., Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck. (© National Portrait Gallery, London)
Consider, for example, the words of Charles Lyell in the opening page of volume 2 of Principles of Geology. Lyell equated transmutation strictly with Lamarck. (Later in the book, however, Lyell also discusses Brocchi by name. Lyell was virtually the only person to do so, save his own father-in-law.) Framing the problem of transmutation in explicitly empirical terms, Lyell ([1832] 1997) challenged his reader to “inquire, first, whether species have a real and permanent existence in nature; or whether they are capable, as some naturalists pretend, of being indefinitely modified in the course of a long series of generations” (183).
Lyell is sneering at what he goes on to characterize as Lamarck’s blatantly absurd claim about the pattern of transmutation. I cite this passage here, anachronistically, simply because it so well typifies the way many natural philosophers felt about species. Whether creationists (like philosopher William Whewell) or those otherwise disposed toward the search for natural causal explanations of the origins of modern species (such as geologist Robert Jameson), pretty much everybody acknowledged the reality and apparent stability of species. What did Lamarck really say?
Lamarck was hired in 1793 to be in charge of invertebrates (animaux sans vertèbres) at the Natural History Museum (Jardin des Plantes) in Paris. It was not uncommon in these early days of natural history for appointments to be made to positions for which the nominee had no particular training or expertise: Charles Darwin’s mentor at Cambridge, John Stevens Henslow, was already Professor of Mineralogy when he was named Professor of Botany in 1825, reflecting his growing interest in the subject. Henslow duly turned himself into a thorough-going botanist. Adam Sedgwick, who was similarly appointed Professor of Geology at Cambridge without any real track record in the subject, quickly became a leading geologist of his time. And so it was, two decades earlier, that Lamarck, taking his appointment seriously, set out to study invertebrate organisms, publishing Systême des animaux sans vertèbres in Paris in 1801, or in “the eighth year of the Republic.” Historian Janet Browne (1995) reports that Darwin read Lamarck’s work on invertebrates while in medical school in the mid-1820s, and would have read the “text of his lecture” (83) on animal change through time.
It is in the introduction to the section “On Fossils” that Lamarck launches into a discussion of what fossils are and why they are interesting. On their own, he says, fossils, typically having lost their original color, have next to no intrinsic interest. But when fossils are seen as “extremely precious monuments” for the study of “revolutions” to which different places on the earth’s surface have been subjected—and the study as well of the “changes that living beings have successively experienced there”—they become of the “highest interest” to naturalists (Lamarck 1801:406).
Lamarck (1801:407) goes on to say that several naturalists (evidently thinking especially of his colleague Georges Cuvier) have claimed that all fossils belong to the remains of animals or vegetables for which there are no living analogues. Cuvier was even then promoting his ideas of “revolutions” on the surface of the globe, the forerunner to modern discussions of mass extinction events. Cuvier was specifically concerned with proving that many species of large fossil mammals, such as the South American Megatherium, were not only extinct, but had no particularly close living relatives.
Not so, says Lamarck, for such naturalists “want to explain everything,” and don’t take the trouble to study the course that nature takes. And here Lamarck (1801:408) begins to walk an interesting tightrope—saying that in fact a small number of fossil species do have living analogues. And besides, among the fossil species without apparent living analogues, many belong to the same genera as are found in the modern oceans, differing more or less from their fossil relatives to the point at which they cannot be considered the same species.
The explanation of why only a few fossil species seem to be the same as living species, Lamarck tells us, is that most fossil species have changed in the course of time. He goes on to say that nothing is constant on the face of the earth, and “diverse mutations” occur, prompted by the “nature of objects and circumstances.” Environmental change prompts changes in “situation, form, nature and appearance,” and a diversity of habitats, a “different way of existing,” followed by “modifications or developments in their organs and in the form of their parts,” such that “every living being must vary insensibly in its organisation and form.” The changes are propagated “through generation [reproduction], and after a long chain of centuries, not only will new species, new genera and even new orders appear, but every species will necessarily be varied in its organization and forms.”
So Lamarck concludes that what is astonishing is not that so few fossil species have living analogues, but that there are any living species at all that are also known from the fossil record. And most of the relatively few fossil species with living analogues still extant must be among the youngest fossils known, for they simply have not had the time to change.
So one cannot really conclude, Lamarck says, that fossil species with no exact living analogues are in fact extinct. Humans may have driven some of the large fossil mammals to extinction, but this is not a matter that can be decided from the fossil record alone, as there are many regions on earth yet to be fully explored.
Hence Lamarck’s tightrope: he wants to deny extinction, but has to admit that relatively few fossil species seem to be identical to still-living counterparts. He argues against external causation for extinction, arguing instead for a form of extinction-through-transmutation: the inevitable and insensible changes in form of species as the ages roll virtually ensures that no living species will be found to be exactly the same as its fossil counterparts. Though he and Cuvier actually agree that many fossil species have no evident exact living counterparts, Lamarck disagrees strongly with Cuvier on why this is so.
In 1809, Lamarck published Philosophie zoologique, easily the better known exposition of his transmutational views. Lamarck’s words leave no doubt that Lyell, Darwin, and others who read him were correct to say that Lamarck saw the organic world in a constant state of flux within phylogenetic lineages, with constant, gradual change from one species to another through time, as well as in space. For example, Lamarck ([1809] 1984) wrote: “Let me repeat that the richer our collections grow, the more proofs do we find that everything is more or less merged into everything else, that noticeable differences disappear, and that nature usually leaves us nothing but minute, nay puerile, details on which to found our distinctions” (37).
Lamarck’s notion entailed the destruction of the creationist view that species are inherently stable, discrete, forever unchanging, and are unconnected to any other species. The alternative view developed by Brocchi and adopted by a number of naturalists was that species are indeed real, and discrete, but are connected in phylogenetic series through a process of birth of descendant species from older ones. And unlike Lamarck, Brocchi and like-minded naturalists were perfectly willing to concede that species die—become extinct—through natural causes, though they disagreed on what those causes may be. And even a few (like Jameson) entertained a sort of mixture of Lamarckian and Brocchian views.
One final note on Jean-Baptiste Lamarck before moving on to Giambattista Brocchi. Lamarck died in 1829. He was eulogized by his longtime adversarial colleague Georges Cuvier (1836). The eulogy (“elegy”) appeared in English translation in Jameson’s Edinburgh New Philosophical Journal, most likely translated by Jameson himself. The standard interpretation is that Cuvier’s eulogy is one of the unkindest on record. And it is indeed true that Cuvier does not shy away from accusing Lamarck of a hyperactive imagination and the development of ideas in the absence of hard evidence. For example, Cuvier says that “too great indulgence of a lively imagination has led to results of a more questionable kind.”
Cuvier structures the eulogy around the twin themes of Lamarck’s lasting empirical work and his great diligence in mastering new fields, on the one hand, and his penchant (according to Cuvier) of theorizing beyond the known facts, on the other. And we have already seen enough of Lamarck’s writing on transmutation to agree with Cuvier (1836) that “M. de Lamarck could not fail to come to the conclusion that species do not exist in nature; and he likewise affirms, that if mankind thinks otherwise, they have been led to do so only from the length of time which has been necessary to bring about those innumerable varieties of form in which living nature now appears” (15). Lamarck indeed saw species in flux and not really existing in nature.
But (as pointed out by my colleague Stefano Dominici) this is simply not the whole story of Cuvier’s eulogy to Lamarck. When Cuvier (1836) turns to Lamarck’s work on fossil invertebrates, his tone changes as he writes:
There is one branch of knowledge in particular to which he has given a remarkable impulse, the history, namely, of shells found in the bowels of the earth. These had attracted the attention of geologists from the time that the chimerical notion was exploded, which attributed their origin to the plastic force of a mineral nature. It was perceived that a comparison of such as belong to the different beds, and their approximation to those now living in different seas, could alone throw light on this anomalous phenomenon, —the deepest, perhaps, of all the mysteries which inanimate nature presents to our view. (20)
Cuvier, insofar as I am aware, was never a transmutationist in the sense that he ever admitted a need to understand the births of species in terms of natural causes. He was an early champion of the notion that species are real, and die through natural causes. But the births of species? According to historian Martin Rudwick, Cuvier was against Lamarck’s ideas of transmutation, though not necessarily against natural causal explanations of the progressive modernization of fossil faunas. And here, in the elegy to Lamarck, Cuvier is acknowledging that Lamarck turned attention on the comparison of fossil with recent mollusks, thereby starkly posing the question of the origin of species of the modern fauna.
As they “approximate” to those now living, as one collects in progressively younger rocks up the stratigraphic column, light could be shed on this “anomalous phenomenon” that Cuvier pronounced “the deepest, perhaps, of all the mysteries which inanimate nature presents to our view.”
A month or so after Jameson published the English translation of Cuvier’s eulogy to Lamarck, John Herschel wrote to Charles Lyell on February 20, 1836, from Cape Town, commenting on volume 2 of Principles of Geology (1832). In a famous passage, Herschel wrote: “Of course I allude to that mystery of mysteries, the replacement of extinct species by others” (quoted in Babbage 1838:225–227; see also Kohn 1987:413n.59-2). Darwin (1839) saw a published version of that letter some two years later and remarked in Transmutation Notebook E that “Herschel calls the appearance of species, the mystery of mysteries. & has grand passage upon problem! Hurrah.— ‘intermediate causes’” (59; Eldredge 2005:8–9; Kohn 1987:413).
Twenty years later, Darwin (1859c) wrote in the second sentence of On the Origin of Species that “these facts [his observations on the living and extinct fauna of South America] seemed to me to throw some light on the origin of species—that mystery of mysteries, as it has been called by one of our greatest philosophers” (1).
Herschel had already played a big role in fomenting Darwin’s initial enthusiasm for transmutation. Had Herschel’s “mystery of mysteries” been triggered by Cuvier’s eulogy for Lamarck? Whatever the case may be, Cuvier put his finger right on it when he underscored the importance of Lamarck’s comparison between fossil and living species. He could not have liked Lamarck’s conclusions. But in saying that Lamarck was the first to discuss the “mystery” by comparing progressively younger fossils with species of the modern marine fauna, he was really affirming that Lamarck was indeed the one who got evolutionary theory up and running in the new natural philosophy.
BROCCHIAN TRANSMUTATION
Who is this Giambattista Brocchi (figure 1.2)? And how can he possibly be a co-founder of modern evolutionary biology, and the founder of the line of thought that sees species as spatiotemporally real, discrete, stable entities, with births and deaths analogous to those of individuals? If he is that important, why has no one heard of him?
Well, not quite “no one.” The historians Giuliano Pancaldi (1991) and, most recently, Martin Rudwick (1995, 2005, 2008) have certainly heard of Brocchi. Pancaldi coined the expression “Brocchi’s analogy” in reference to Brocchi’s major conclusion that species are as real as individuals, and like individuals have births and deaths explicable through natural causes. And Rudwick (2005) has recently written that Brocchi’s work “also suggested . . . that the origin of species, might have an equally natural, yet episodic, mechanism, analogous to the birth of individuals” (527). Most recently, my colleague Stefano Dominici (2010; see also Dominici and Eldredge, 2010), a geologist/paleontologist at the Museo di Storia Naturale, University of Florence, recognized the importance of Brocchi’s work and has published extensive excerpts, translated into English, from Brocchi’s monograph, concentrating on the “beautiful speculations” of Brocchi’s theoretical discussions. What did Brocchi say?
FIGURE 1.2 Giambattista Brocchi. (By permission, Museo Biblioteca Archivio, Bassano del Grappa)
Giambattista Brocchi’s monograph Conchiologia fossile subapennina (1814) was the second important treatment of Tertiary molluscan fossils. Only Jean-Baptiste Lamarck’s work on the fossils of the Paris Basin was earlier. Both men had compared their fossils with the known extant species of marine mollusks of their respective countries. They came up with rather different conclusions.
On Georges Cuvier’s claim that no species known as fossils are still extant, Brocchi in part agreed with Lamarck (though not mentioning Lamarck explicitly by name), that species known as fossils are indeed still alive in the modern fauna. Brocchi claimed that Cuvier himself more or less knew that, or at least that the fossil record showed progressive approximation to the living fauna through time. Brocchi, addressing Cuvier’s ideas on catastrophic extinction, wrote that “it does not account for the loss of fresh water shells and, what is more important, it cannot be applied to the loss of terrestrial quadrupeds, a matter on which he [Cuvier] has himself observed that all unknown species belong to the rocks older than those others that bear remains of known species or more similar to living ones” (Dominici 2010:593).
To Brocchi, the whole purpose of molluscan systematics is to shed light on the origins of modern species, and to explain their origins in natural (secondary) causal terms: “Since indigenous species are mixed with exotic ones, and those which we deem lost are together with others that nevertheless exist, we want to produce a system to reconcile facts of such variety, and that by satisfying all concomitant circumstances, tries to explain them without outraging reason, and in consonance with physics” (Dominici 2010:589).
“In consonance with physics” indeed. And to make his quest as plain as possible, Brocchi talks of the futility of analyzing lineages of extinct species that have no possible bearing on understanding the origin of the modern fauna, writing disdainfully of “busying ourselves to plot a distinct genealogy of some obscure descent since long gone” (Dominici 2010:588)—an evident reference to the study of genealogies of long-since extinct groups, such as the Mesozoic ammonoids.
But note the word “genealogy” here. Both Lamarck, and then Brocchi, were dealing with skeins of species that were so closely similar that the main debate was whether the species were the same, or whether they were closely related, but slightly different, species within the same genera. Naturalists since at least Carolus Linnaeus (the tenth edition of Systema Naturae, widely regarded as the starting point of modern systematic biology, was published in 1858) had long since become accustomed to talking of “natural groups” of “allied forms,” but few if any of them (at least publicly) harbored transmutational views until Lamarck and Brocchi pointed to lineages within progressively younger fossil faunas, up to and including species still alive in the modern fauna, and sought an explanation of this “anomalous” “mystery” (Cuvier’s words) in natural (secondary) causal terms. There can be no doubt that Linnaean-style systematics was the necessary forerunner to a full-blown search for an explanation of genealogies generally, and specifically of the advent of the modern fauna. That was the task Lamarck and Brocchi set for themselves.
But if Brocchi saw no immediate payoff for studying the phylogenies of wholly extinct fossil taxa, he also, to be fair, admitted that there is little use to simply cataloguing the shells of the modern Italian molluscan fauna: “I agree that wanting to describe all the shells of the sea, to sort them by order, genera and species does not lead to great consequences,” except if they serve as a measuring stake to chart the progress of the advent of the modern fauna; Brocchi continues: “But if no one dared to treat in an academic way marine conchology, how could we usefully study fossil conchology which gives units of measure in geology and paves the way to so many beautiful speculations?” (Dominici 2010:589).
Beautiful speculations indeed—referring to Brocchi’s own theory, so different from Lamarck’s, of the dynamics underlying the patterns of stability and change, or the progressive appearance and disappearance of species. Before we look more closely at Brocchi’s “beautiful speculations,” though, we must look more closely at his thoughts on the nature of species, their appearances and disappearances, in the fossil record.
To begin with, Brocchi was dealing with younger rocks (hence fossils) than Lamarck. Lamarck’s Paris Basin fossil faunas were Eocene in age (somewhere between 56 and 34 million years ago). In contrast, Brocchi’s Upper Tertiary Miocene-Pliocene-Pleistocene strata were much younger, for the most part at somewhere during the past 5 million years. Thus it comes as no surprise that Lamarck could point to relatively few (though there were some!—having his cake and eating it too) species in the fossil collections that could be said to be still alive in the modern fauna. But Brocchi estimated that some 50 percent of the fossil species could be found still living in the offshore Italian waters.
Charles Lyell later became famous for proposing (in volume 3 of Principles of Geology) that Cenozoic rocks around the globe could be classified and correlated based on percentages of the species of the living fauna that could be identified in the fossil record. In the first proposal for the chronological subdivision of European Tertiary rocks, from the oldest to the youngest subdivisions, Lyell ([1833] 1997:394–398) estimated that only some 3.5 percent of known Eocene species survive into the modern fauna (in close agreement with Lamarck’s minimalist claims), and roughly 18 percent for the succeeding Miocene. For the still younger “Older Pliocene,” Lyell saw a range of from 33 percent to slightly over 50 percent survival of the fossil species into the modern biota; the rocks of Lyell’s “Older Pliocene” include those studied by Brocchi, who estimated approximately a 50 percent species survivorship. And finally, 90 percent of species known as fossils in the “Newer Pliocene” (later known as the Pleistocene) are still present in the modern fauna.
Clearly Lyell, reputedly not a transmutationist until (finally!) Darwin published Origin of Species in 1859, had nonetheless been inspired by (or simply cribbed from) his predecessors—Lamarck, to some degree, and almost certainly Brocchi—to propose the famous “percentage of the Recent” relative dating of marine Cenozoic fossils, and thus the rocks in which they are found. And the anti-transmutationist Lyell was doing this based on the work of two people, Lamarck and Brocchi, whose “beautiful speculations” were distinctly transmutational in character.
Brocchi, as quite, almost explicitly, distinct from Lamarck, saw species as discrete, real, and pretty much stable entities. In what Stefano Dominici and I think must be a side-swipe at Lamarck’s vision of species constantly changing, Brocchi wrote that “the alterations that take place in the animal machine and that are the symptoms of decline of the species, do not produce a large change in structure, what would be a true metamorphosis” (Dominici 2010:593).
In other words, species do not change all that much in time, though they may show some signs of aging. Brocchi’s interpretation of fossil species is that they are discrete and stable. They do not display the sort of large-scale change that Lamarck claimed pertained to the fossil mollusks of the Paris Basin.
Which brings us directly to the core of Brocchi’s “beautiful speculations.” Biologists and historians of evolutionary biology tend to focus first on mechanisms: Darwin is said to have bested Lamarck because he had a more plausible mechanism of evolutionary change: “natural selection” as opposed to “inheritance of acquired characters.” But this is not the whole story by far, as what really separates players in the game of evolutionary biology (now as much as in the past) are the often conflicting but all-important empirical claims of what evolutionary patterns should look like in any particular data set, be the data molecular, systematics of living biota, fossils, whatever.
We have already seen that Lamarck and Brocchi differed drastically on the claims of some of the most fundamental empirical patterns of biology: the constant and complete spatiotemporal flux of species claimed by Lamarck, contrasted with Brocchi’s vision of species as discrete, more or less stable entities, with natural births and deaths creating lineages of descent leading right up to the appearance of modern species. And we have seen enough of Brocchi’s words to know that, though the pattern of stability of species empirically matched the standard creationist claims of his day, he was looking for an explanation of the progressive “younging” of fossil faunas up to the advent of modern species in natural (secondary) causal terms (that is, “in consonance with physics”). Brocchi, in other words, was no creationist.
One tends to search in vain for causal mechanisms among early writers of a transmutational bent. Lamarck was an exception, granted; he was criticized not so much for his putative mechanism, but for his claims of constant flux between species through time and in space. Yet it is not accurate to say that early transmutationists (and here I am thinking especially of Brocchi) were more intent on establishing the reality of the progressive origin of one species from another through time than they were for causal mechanisms.
To the contrary: Brocchi and other early transmutationists were keenly aware that for their science to approach others, such as the already established role-model science of physics, they had at least to consider the thorny question of mechanism.
One reason why transmutational mechanisms remained elusive, of course, is that relatively little was understood of the basic biology of organisms. By the time Darwin discovered natural selection in the late 1830s, those interested in biology knew that organisms tend to resemble their parents, and that there is heritable variation in populations of every species. Beyond that, no one had the faintest idea why—though it must be said that with the simple addition of the principle of population-size regulation borrowed from Thomas Malthus, Darwin had all he needed to formulate what still stands as the essential statistical law of evolution: natural selection.
But self-conscious awareness of the primitive state of biological knowledge is not the whole story that explains the dearth of speculations on the origin of species. Martin Rudwick (2008) has remarked that “it was widely accepted among savants, even in Britain, that some kind of natural process, as yet unknown, must be responsible for the origin of new species” (480).
Rudwick was writing of the 1830s, but his comment applies, with somewhat lesser force, to the two or even three decades preceding the 1830s. Rudwick was alluding to the hush-hush nature of the question of the origin of species, saying that smart money knew that there must be a natural causal explanation for the existence and origin of species, but with no one daring to address the issue publicly. Very simply, there was a general reluctance to discuss the origin of species in natural causal terms throughout the 1820s and beyond. That attitude prevailed even in Darwin’s time and was the main reason Darwin kept his thoughts to himself for so long. I say this even though I am aware that it has recently become fashionable again to blame Darwin’s delay in publishing not on the frightening prospect of public outrage, but on his methodical attempt to keep his scientific ducks in a row in order to present as convincing a case as possible for transmutation. That’s ridiculous. The structure (content and order of chapters) of Darwin’s Origin of 1859 is the very same as his first extended essay on evolution—“Pencil Sketch” of 1842.
If people shied away from discussing transmutation, they found the discussion of extinction much less daunting. Cuvier led the charge with his claim that extinction is real, and that there were multiple extinction events, not just one (the “biblical deluge”) that accounted for the apparent loss of ancient species, including the large Tertiary mammals. The biblical deluge remained a hot topic of controversy in geology/paleontology at least into the early 1830s. For example, in the early pages of Darwin’s Beagle voyage Geological Diary, Darwin himself was constantly mooting (and rejecting) the idea of a single biblical flood as he studies the sediments of southern Argentina.
The early transmutationists considered four basic causes of extinction: external, physical, natural causes (either staggered, as Lyell thought, or concentrated in multi-taxon spasms, as Cuvier proposed); and—as virtually everyone considered as a possibility, or as Lamarck proposed—that species suffered a sort of “evolutionary pseudo-extinction” simply by evolving directly into their ancestors (an idea taken seriously as recently as in the mid-twentieth-century writings of the paleontologist George Gaylord Simpson). Or extinction is a false signal: early naturalists were mindful that the world had yet to be fully explored, and new species were being discovered all the time. Perhaps no species had truly become extinct, but are instead still alive, awaiting discovery. Darwin wrote in Geological Diary that he had heard reports when first arriving in southern South America that a giant mammal—perhaps the missing and presumed extinct Megatherium—might still be alive and well in the South American interior.
And then there was the fourth possibility. This one was the brainchild of Brocchi (1814), as part of his core “beautiful speculations”: “I thought I had enough inductions to venture to say that it is an established law that species die like individuals, and that they are bound to make their appearance in the world for a fixed span of time” (Dominici 2010:591).
Hence “Brocchi’s analogy”: specifically, with respect to extinction, Brocchi saw little evidence for external, physical causes for the extinction of species, though he admitted that such could “cut short” the life of species before their time. Instead, he suggested that species might have innate longevities, much as individuals do. Again, he posed this as a natural cause, implicitly suggesting that, however much God may be watching over an individual, and ultimately be responsible for their births and deaths, nonetheless the births and deaths of humans (and of course all other individual organisms) have natural causes.
And neither individuals nor species live forever. Absent compelling evidence of physical, external causes, Brocchi simply suggested that species, like individuals, must have internal longevities.
And as Rudwick has said, by implication, at least, the births of species also have natural causes. This, too, is analogous with the situation in individuals. But that’s it: even less speculation as to causes for species births than Brocchi offers for species extinction.
But the key here is the search for natural causal explanations of natural phenomena. The clear implication is that species have births through natural causes every bit as much as they suffer extinction through natural causes. And this is the way early naturalists often skirted the topic of the origin of species per se: talking about extinction—the deaths of species—and suggesting that extinction is the converse of the problem of species’ origins.
We need now to show that Brocchi’s work was known and discussed in Great Britain from about 1816 to 1830. Beyond that point, Darwin picked up and developed these themes on the natural births and deaths of species on his own.
BROCCHI AND LAMARCK IN GREAT BRITAIN, 1816–1830
Tying the issue of the advent of the species of the modern fauna to the search for natural causal explanations is relatively straightforward, at least in the British literature of 1816 to 1830. Undoubtedly much more exists to be uncovered by future historians. Yet there is enough known at this point to link both Jean-Baptiste Lamarck’s and Giambattista Brocchi’s disparate transmutational views to Charles Darwin, who, even before he became a medical student in Edinburgh in 1825 (at the age of sixteen), had apparently already read his grandfather Erasmus Darwin’s Zoonomia, replete with his evolutionary views.
As copies of Brocchi’s (1814) two-volume monograph began to show up in Paris, London, Edinburgh, and other European seats of learning of the still-young scientific enterprises of geology and paleontology, one came to the hands of Leonard Horner, a Scottish geologist and the future father-in-law of Charles Lyell. Horner appears to have been fluent in Italian, and had visited family members who were living in Italy. So it was only natural that Horner would take an interest in Brocchi’s work—and in 1816, he published a twenty-four-page review of it in the Edinburgh Review.
At the outset of the review, Horner expresses his overall admiration for Brocchi’s work, including Brocchi’s plates illustrating his fossils, which Horner (1816), in the very last sentence, proclaims to be “more beautifully executed than any thing of the kind we have ever seen before.” Of the work in general, Horner wrote that “this appears to us to be a work of very great value and merit.” He summarizes in very general terms Brocchi’s contents, saying that the “chief object is to describe the fossil shells that are found in the clay, and gravel, of which the hills that skirt the base of the Apennines are composed, and to compare them with their prototypes now existing, either in the adjoining or more distant seas” (156).
But then, after a short summary of the organization and contents of Brocchi’s monograph, Horner broaches his main criticism of the work, as he launches into a short lecture on the nature and philosophy of science. Basically Horner says that “facts” should be kept strictly separated from theory, and that “although there is not, we think, any reason to suspect that the facts have been in the slightest degree distorted, for the purposes of adapting them to some favourite system, we should have been glad to have had, in this Introduction, the descriptions, and the author’s reasonings upon them, less mixed up together” (157).
So Horner is saying that Brocchi has a “system,” or at least some conclusions too freely interspersed with the objective results to please Horner’s taste. But Horner hastens to add: “We are by no means of opinion, that the geologist ought to confine himself to a bare narration of facts, and that he ought to abstain from all theoretical explanations upon them. . . . It must be admitted that theory is the ultimate object of all geological researches” (157).
He goes on to cite Brocchi to the same effect, in which Brocchi says that those who oppose hypotheses in geology are generally “ignorant of the use of them.” So Horner is basically in Brocchi’s corner, though he concludes this short disquisition of the philosophy of science by saying, for the rest of the review, that “we shall confine ourselves principally to the matters of fact. To enter into a consideration of the author’s theoretical opinions, would extend our remarks beyond our limits, unless we were to omit what we have no doubt will be more generally interesting to our readers” (158)
So Brocchi indeed has a system, or at least some general conclusions, what Brocchi himself refers to at one point as “beautiful speculations.” But Horner is not going to bother his readers with them, although he does tell his readers that they are there.
And true to his word, most of the rest of Horner’s review of Brocchi’s monograph applies to Italian geology in Brocchi’s discussion, augmented to some degree by the results and observations of others.
Only near the end of this review does Horner turn to what he said at the outset was the main purpose of Brocchi’s work: the description of the fossil shells flanking the Apennines, along with a comparison with their “prototypes now existing” in the present seas. Horner reports that Brocchi’s fossil shells “are not scattered confusedly through the different beds, but often appear to be distributed in families and in distinct species”—meaning that many mollusks of the same distinct species (and even families) seem to co-occur. On the other hand, the species are usually not restricted to the same type of sedimentary rock, and they are not always present in otherwise identical lithologies.
Horner then reports that “the fossil shells of the sub-Apennines may be divided into two general classes, the one comprehending the shells that are still found in the sea, the other comprehending those whose prototypes are unknown” (174). Two pages later, he reports:
In the catalogue which Lamarck has given of the fossil shells that have been found in the neighbourhood of Paris, there are about five hundred species; and it is wonderful how few of them resemble those found in the Sub-Apennine Hills, and how many genera there are among them, wholly unknown in Italy. But the most remarkable difference in the fossil shells of the two countries, is in those of which the prototypes are unknown. These greatly predominate in France, and, with a few exceptions, are wholly different from those which exist in Italy. (176)
Never mind that Horner is determined to designate the “still living” members of a species as the “prototype,” rather than calling the fossil specimens the prototypes of the living. Perhaps there is some creationist perspective at work here. But nevertheless, Horner makes it clear that members of the fossil faunas in both France and Italy have living counterparts in the seas in their still-adjoining neighborhoods. Though this, as Horner promised, is a far cry from recounting Brocchi’s deeper conclusions, he is nonetheless reporting an analysis based on Brocchi’s (and Lamarck’s) comparison of their respective fossils and the still-extant species of the modern biota in Italy and in France: analytic conclusions based on empirical evidence that unmistakably points to the appearance of elements of the modern fauna at some point in the geological past. Indeed, the direct comparison of Lamarck’s and Brocchi’s results is in itself significant, given what the world already knew about Lamarck’s conclusions. Horner’s statement that the search for theory to explain phenomena in general terms is legitimate and important, and his clear pronouncement that Brocchi in fact has published such a theory, apparently served to draw attention to the potential importance of Brocchi’s work, even though Horner himself was loath to describe Brocchi’s conclusions in any detail.
ROBERT JAMESON, ROBERT GRANT . . . AND CHARLES ROBERT DARWIN
Charles Darwin (1809–1882) grew up helping his father tabulate the flowering peonies in the family garden, making collections of rocks, roaming the fields, and shooting the wildlife. As Darwin ([1876] 1950) recalled in Autobiography, his father once told him that “you care for nothing but shooting, dogs and rat-catching, and you will be a disgrace to yourself and all your family” (17). Despite growing up in a well-to-do household, Darwin’s father, Robert Waring Darwin, was determined that his son have an education befitting his family background—and more than that, have a profession.
Robert Waring Darwin was a physician, as was his famous father, Erasmus Darwin, before him, as well as many of the male collateral kin. Edinburgh was well established as the medical school of choice, and Robert decided to send young Charles there to follow in the family footsteps. This was in 1825, when Charles was only sixteen. Charles’s older brother Erasmus (“Ras”—who trained in, but never practiced, medicine) was already enrolled at Edinburgh, softening the blow of leaving home and training for a profession that alternately bored and frightened him (though he did show some promise as he went with his father on some of his rounds back at home).
When first looking at Darwin’s pre-Beagle education in detail, I was surprised to learn that Edinburgh was a hotbed of advanced, modern, even radical thinking. Radical scientific ideas, particularly the growing debate and open advocacy of various forms of transmutation in continental Europe, were definitely part of the intellectual currency in Edinburgh in the 1820s.
I knew about the medical school of course. But I had no idea that it housed, along with its lecture halls and operating theaters, the best natural history museum at the time in Great Britain. I had never heard of the Edinburgh New Philosophical Journal—a goldmine of scientific observations, results, and discussions of theory. I hadn’t known, either, of the Plinian Society and other discussion groups, formal and informal, that regularly met to discuss the latest ideas. Nor had I ever heard that at least one of the lectures in one of Darwin’s courses was entitled “On the Origin of the Animal Species.”
I knew none of these things about the medical school—even when I glimpsed its shadowy presence one winter’s night when I alighted in Edinburgh from a train from London. I was there to look over some of the cornets in the musical instrument collection overseen by Arnold Myers, renowned brass musical instrument historian. I was living outside my paleontological/evolutionary skin on that quick trip. I had no idea whatsoever that I was crossing Darwin’s footsteps as I entered Reid Concert Hall to see the horns in the basement, paying no heed whatsoever to the remains of a building next door that had been so important in the emergence of evolutionary theory.
In retrospect, I wonder why I was so surprised to discover that Edinburgh had been such a hotspot of radical biological thinking. After all, I had known since the 1960s that Edinburgh had been home to James Hutton (1726–1797), considered the founder of modern geology. Hutton showed conclusively that molten rocks that later cooled and hardened (igneous rocks, such as lavas) can be injected into, or lie on top of, sedimentary rocks. His was the linchpin demonstration that not all rocks were formed from chemical precipitates: the theory called “Neptunism,” which up until then had been the prevailing geological theory.
But it was Hutton’s demonstration of the enormity of geological time, and his conviction that processes of erosion, deposition, volcanoes and the like were always at work in the geological past, that was really important to me as a young paleontologist. Hutton taught us that the history of the earth can be interpreted in a rational way by considering the world around us today, and by paying close attention to what the outcroppings of rock have to tell us if we only examine them carefully. This aspect of Hutton’s work was the direct forerunner to Charles Lyell’s principle of uniformity: the processes we see operating today are the very same that shaped the events in the long history of the earth.
Hutton was a farmer, geologist, and also a physician, initially taking courses at the Edinburgh medical school before completing that phase of his studies on the Continent. My first trip to Edinburgh was in 1973, the year after “Punctuated Equilibria” (Eldredge and Gould 1972a) had appeared. I was there to do some field work collecting trilobites with Euan N. K. Clarkson, whose work on trilobite eyes in the 1960s had shown me the way to understanding the evolution of my own species in North America. That, in turn, was the work that led me to the notion of punctuated equilibria.
But this was my first trip to Europe, and of course we saw the sights in Edinburgh. One stop was Holyrood Palace, Scottish residency of the British royal family. And just outside, in Holyrood Park, loomed the Salisbury Crags and the hill known as “Arthur’s Seat,” where Hutton made his observations that led him to demolish Neptunism, as the evidence there is unequivocal that igneous rocks are not formed as chemical precipitates from cold oceanic waters. Hiking up the stretch to Arthur’s Seat, with its magnificent view of Edinburgh (and the Firth of Forth to the north) was in itself exhilarating. But even more exciting was examining the evidence first-hand of the baking of sedimentary rocks by a molten mass of lava that had subsequently cooled to stone. I saw the evidence, knowing what role it played in the history of my science, and was thrilled.
The “deep time” revealed in Hutton’s work, and his direct stimulus to the later work of Charles Lyell, which in turn had had such an effect on the young Darwin, was an utterly necessary precondition for the serious contemplation of the history of life on earth. Small wonder, then, that Edinburgh’s intellectual environment also fostered equivalent, radical ideas in zoology, as they had a generation earlier in geology.
But the story of Darwin’s mentors in medical school, and what he himself absorbed while he was there, was far less known in the 1960s than the saga of Hutton (and his “Boswell,” John Playfair). I was ignorant of all of this, but should not have been particularly surprised when I finally learned, in the first decade of this century, of the foment around transmutational ideas that seethed in Edinburgh. The creative intellectual ferment of Edinburgh in science in the late eighteenth century and first decades of the nineteenth had carried on in biological topics well into the 1830s.
Robert Grant (1793–1874), himself an Edinburgh-trained physician, was an out-and-out champion of Jean-Baptiste Lamarck. Almost solely through Darwin’s word, Grant has become easily the most famous of what historian James Secord has called “the Edinburgh Lamarckians.” His connection to Darwin was extremely important.
But it was Robert Jameson, originally known to me only as an important early geologist who was stodgily one of the last defenders of Neptunism, who was the real central mover-and-shaker of the new wave of thinking. It was Jameson who founded and ran the natural history museum. It was Jameson who founded, edited, and wrote for the Edinburgh New Philosophical Journal, almost undoubtedly the author of the first (and most probably the second) of two anonymous essays exploring transmutation, as well as, presumably, a précis of the work of the transmutational ideas of the Frenchman Étienne Geoffroy Saint-Hilaire, also Giambattista Brocchi’s death notice, Georges Cuvier’s eulogy of Jean-Baptiste Lamarck, and, I suspect, many more goodies yet to be unearthed by modern scholars.
Darwin ([1876] 1950) himself writes that “the Plinian Society was encouraged, and, I believe, founded by Professor Jameson” (23)—the latter statement disputed by some historians. The Plinian Society was a social group where students would gather to discuss their research and opinions on the hottest topics of the day in natural history. And it was indeed Jameson, in the fifth edition (1827) of the translation of Cuvier’s Essay on the Theory of the Earth, who added a discussion to the section on illustrations, couching his thoughts on transmutation (not labeled as such) in terms of the advent of the modern fauna.
Darwin wrote a list of “books that I have read thro since my return to Edinburgh,” presumably meaning the start of his second term in medical school in 1826. Ras had departed for London, and Darwin had turned to a deeper involvement with his fellow students, and with the invertebrate zoologist Robert Grant. The list of books is eclectic, but includes three or four items of special interest: his grandfather Erasmus’s Zoonomia, Cuvier’s Theory of the Earth (Darwin had a personal copy of Jameson’s fifth edition, which appeared early in 1827), “several numbers in the New Edinb: Philos Journal” (Jameson’s journal), and seven “Pamphlets by Drs. Grant & Brewster on Nature History”—some of the last undoubtedly including Grant’s papers in Jameson’s journal, one of which was a paper by Grant with Darwin’s own (unattributed) original observations on the motile “ova” (larvae, actually) of the bryozoan Flustra. Grant had trained Darwin in field collecting and microscopic study of marine invertebrates.
If it weren’t for the second volume of Lyell’s Principles of Geology (1832), I might never have heard of Brocchi, at least from my own readings, despite the fact that his ideas are all over the place in books and articles of the 1820s and 1830s, and were demonstrably the basis of Darwin’s deliberate testing of Lamarckian versus Brocchian versions of transmutation while on the Beagle. And while Grant seems to have been performing the still widely practiced petty pilferage wrought by mentors mining their students’ work for their own gain and glory when he ripped Darwin’s data off, it is Darwin’s own behavior that has arrested my attention in this regard.
As James Secord has said, basically the only thing anyone seems to know about Jameson comes from Darwin’s Autobiography, written for his family’s eyes only when Darwin was sixty-seven years old, about fifty years after he was at Edinburgh. I think the portraits that Darwin paints of both Grant and Jameson are fraught with a desire to retain an aura of his own originality, and are, at least in Jameson’s case, deceptive and off-putting.
Of Jameson, Darwin ([1876] 1950) writes: “During my second year at Edinburgh I attended Jameson’s lectures on Geology and Zoology, but they were incredibly dull. The sole effect they produced on me was the determination never as long as I lived to read a book on Geology, or in any way to study the science” (23).
We’ll meet Darwin’s denial that someone had had any “effect” on him again, as he says the very same thing, not only about Robert Grant, but also about his own grandfather. It is like a mantra, this “no effect on me” repeated claim, yet it is always followed by a mitigating, second-thought statement. Here, in the next sentence on Jameson, is Darwin’s “on the other hand” second thought: “Yet I feel sure that I was prepared for a philosophical treatment of the subject” (23).
Darwin embellishes his disdain for Professor Jameson, writing in Autobiography:
Equally striking is the fact that I, though now only sixty-seven years old, heard the Professor, in a field lecture at Salisbury Craigs, discoursing on a trap-dyke, with amygdaloidal margins and the strata indurated on each side, with volcanic rocks all around us, say that it was a fissure filled with sediment from above, adding with a sneer that there were men who maintained that it had been injected from beneath in a molten condition. When I think of this lecture, I do not wonder that I determined never to attend to Geology. (23)
Darwin was a hip young student who knew that the Salisbury Crags (I love the Scottish “Craigs”) were a huge piece of Hutton’s evidence. Darwin’s probably anachronistically advanced terminology in this passage shows that he, even as a young student, thought that Professor Jameson was hopelessly out of date.
And I cannot help but observe that our visit to Salisbury Crags/Arthur’s Seat in Holyrood Park in 1973 was the first, wholly inadvertent, place where my path crossed the footprints, not only of James Hutton, but also those of Charles Darwin. I love that.
As to Jameson not inspiring him, never mind that he had been reading the fifth edition of Jameson’s translation of Cuvier’s Theory of the Earth, replete with Jameson’s own illustrations. Never mind that one or more lectures (the number isn’t clear) in Jameson’s course had been entitled “On the Origins of the Animal Species.” Methinks the sixty-seven-year-old Darwin doth protest too much.
Apparently it was the anthropologist Loren Eisley who first drew attention to the short, unsigned essay “Observations of the Nature and Importance of Geology” (1826), in the first volume of the Edinburgh New Philosophical Journal. That it was in fact written by Jameson, the journal’s editor, as James Secord (1991) has persuasively argued, is bolstered by a lingering, wistful hint of Neptunism, that school of geological thought that held that the rocks of the earth’s crust all originated as precipitates in the primordial ocean. Near the end of this essay, the author writes “whether granite be a production of fire or water.” Jameson was known to have been one of the very last defenders of a doctrine that most geologists had abandoned by the mid-1820s.
“Observations on the Nature and Importance of Geology” ([Jameson] 1826) is a strong statement on transmutation. It mixes distinct Brocchian and Lamarckian elements, though Lamarck is the only one of the two mentioned by name (perhaps the reason why many historians have supposed that Robert Grant was the author). It delivers a thumbnail sketch of the economic (including agricultural) and even moral significance of geology, constituting an encyclopedic survey in capsule form of the values of this branch of science in fact echoed in the structure of Grant’s “Essay on the Study of the Animal Kingdom” ([1828] 1829), discussed shortly. There is no direct record that “Observations on the Nature and Importance of Geology” was in one of the “numbers” (issues) that Darwin read in this journal, though some historians have found it difficult to believe that he hadn’t in fact read it. Among the notable, isolated gems in this essay are the word “evolved” in a totally unambiguous context: Lamarck “maintains, that all other animals [other than “infusorians”], by the operation of external circumstances, are evolved from these [worms] in a double series, and in a gradual manner” ([Jameson] 1826:297). He also uses the catch-phrase “origin of species” when he writes, “Geology does not inform us merely of the origin of animal species, but also of their destruction” (297).
Jameson (the presumed author of “Observations on the Nature and Importance of Geology”) makes the very interesting point that the physical side of the history of the earth seems very different from the history of life. There is no discernible progress from simple to complex in the rocks of the earth’s crust. If anything, to Jameson, the oldest rocks seem to be “the most compound.”
In contrast, there is a gradation from simple to complex in both the spectrum of the anatomies of currently living species (in the two separate sets of them distinguished by Lamarck) and the fossil record of the history of life: We “meet with the more perfect classes of animals, only in the more recent beds of rocks, and the most perfect, those closely allied to our own species, only in the most recent; beneath them occur granivorous, before carnivorous, animals; and human remains, are found only in alluvial soil, in calcareous tuff, and in limestone conglomerates” (297). As we shall soon see, Jameson was not reluctant to include humans in his views on the advent of the modern fauna.
And the “sagacious” Lamarck “has expressed himself in the most unambiguous manner” to the effect “that all other animals, by the operation of external circumstances, are evolved from these [worms] . . . in a gradual manner.” Thus “the scale of gradation, according to which he arranges the animal kingdom, is, at the same time, the history of their origin; and the discovery of this truly natural method, the most important problem of the natural philosopher” (297).
Thus Jameson (if indeed he wrote these words) is strongly in favor of the search for natural causes underlying natural phenomena. The rest of this paragraph is worth quoting in full:
Although it should not be forgotten, that this meritorious philosopher [Lamarck], more in conformity with his own hypothesis than is permitted in the province of physical science, has resigned himself to the influence of imagination and attempted explanations, which, from the present state of our knowledge, we are incapable of giving, we nevertheless feel ourselves drawn towards it, and these notions of the progressive formation of the organic world, must be found more worthy of its first Great Author than the limited conceptions we commonly entertain. (297)
This presumably includes such “limited conceptions” as the notion that each species is separately created by God, and that the unproven “explanations” probably referring to Lamarck’s mechanisms is, I think, borne out by yet a third anonymous contribution (in the same journal and almost certainly again by Jameson), summarizing the experimental results of Étienne Geoffroy Saint-Hilaire, discussed shortly.
There follows a remarkable page examining theories of extinction, headed by the already quoted comment that geology sheds light not only on “the origin of animal species, but also [on] their destruction.” First the author says that, of the “vast number of animal remains” in the fossil record, “but few belong to species now living, and these only, in the most recent rock-formations.” The vast majority of species once alive are long since gone. And he says that one explanation for apparent extinction is that many living species have yet to be discovered.
The writer then asks whether “this destruction . . . ha[s] been the result of violent accidents, and destructive revolutions on the earth”? We have independent evidence that Jameson did not accept Cuvier’s ideas on “revolutions” (mass extinctions), from his own sections accompanying the translation of Cuvier’s text. He goes on:
Or does it not rather indicate a great law of nature, which cannot be discovered by reason of its remote antiquity? Within the narrow circle of vision in which the organic world manifests itself to our observation, we observe individuals only going to destruction, and in opposition to that, great preparations made for the preservation of the species. But if all living perish, may no point of duration have been fixed for the species; or do we not rather, in these signs of a former world, discover a proof, that, from a change in the media in which organic creatures lived, and from powerful causes operating upon them, their power of propagation may be weakened, and at length become perfectly extinct? Is the continual decrease, then, which we observe among some species, a consequence of the various modes of destruction they experience from the hand of man, or may it not rather be produced by natural circumstances, and be a sign of the approaching old age of the species? (298)
So here is Brocchi, with individuals and species analogized, and the interesting addition of individuals “going to destruction,” but making “great preparations” for the survival of the species as a whole—by “generation” (reproduction). Like Brocchi himself, the discourse is limited to the causal explanation of the extinction of species, in the context, though, of the assumption that natural causal explanations for the origins of species will ultimately be found. And though the phrase “old age” resonates in pure Brocchian fashion in the last words of the paragraph’s final sentence, mention is made also of the possibility that the “powers of propagation” may be weakened from external, environmental causes.
But then the author of this essay turns to Lamarck’s idea that many species become extinct simply by slowly evolving themselves out of existence: extinction of a species is a side-effect of its having been transformed into a descendant species. The writer begins with the admission that “the distinction of species is undoubtedly one of the foundations of natural history; and her character is the propagation of similar forms”—meaning that species are discrete, and that the individuals within species “propagate” similar offspring:
But . . . are these forms as immutable as some distinguished naturalists maintain; or do not our domestic animals and our cultivated or artificial plants prove the contrary? If these, by change of situation, of climate, or nourishment, and by every other circumstance that operates upon them, can change their relations, it is probable that many fossil species to which no originals can be found, may not be extinct, but have gradually passed into others. (298)
So here, right after Brocchi, is pure Lamarck: the reason why so few living species can be found as fossils is at least in part because those fossil species kept on slowly being transformed into the species now alive in the modern world. Note that “originals” here means not the ancient species, but the living ones—just as Horner (1816) used the word “prototypes” in the review of Brocchi. And it is interesting, too, that the author of this essay invokes domestic animals as evidence for mutability.
But why is there little direct evidence of such slow, steady, gradual change from an ancestral species into another, including living species from recently “extinct” species whose remains are found in the youngest sediments? The author of this piece does not invoke a poor fossil record (though he does concede earlier in the essay that the record is incompletely known and often the fossils that have been found are poorly preserved). Rather he invokes, in this 1826 essay, the vast reaches of geological time. He maintains that change is very slow. True, he remarks, “We indeed observe that the Ibis, which was worshipped in ancient Egypt, and preserved as a mummy, is still the same in modern Egypt; but what are the few thousand years to which the mummy refers, in comparison with the age of the world, as its history is related by geology” (299).
Napoleon’s foray into Egypt ignited a fierce discussion among the Parisian natural philosophers. Cuvier twitted his pro-transmutational colleagues Lamarck and Geoffroy on this lack of change between mummified and modern sacred ibises, and the author here is simply agreeing with the transmutationists.
One possible, albeit slight, argument that Darwin indeed read this essay was that, though he examined plankton hauls and individual specimens of bryozoans, octopi, corals, nudibranch mollusks, and fossil marine invertebrates, almost none of his observations on invertebrates can be firmly linked with his early speculations on transmutation. Rather, it was the living and fossil species of vertebrates (chiefly birds and mammals—though one snake also stands out) that provided the patterns that brought Darwin to favor, not only transmutation, but a distinctly Brocchian, rather than a Lamarckian, brand of transmutation. I always thought that Darwin focused on vertebrates over invertebrates because he was surer of the biogeographic affinities of vertebrates: edentate mammals, for example, were known to be characteristic of South America. He wanted to be sure that he was looking at the patterns of stability and change in time and space of species that could not also be found—and evolving—elsewhere.
Thus it is striking to read these words in “Observations on the Nature and Importance of Geology” ([Jameson] 1826):
As there are among dicotelydons, that is, among the most perfect plants, no species, which are at the same time indigenous to the hot climates of the old and new worlds, so both halves of the globe in the same zone possess mammiferous animals, birds, reptiles, and insects peculiar to each. Species common to both are found only among inferior gradations of organization, and species of a higher order are found only in those high northern latitudes, where the continents were undoubtedly at one time conjoined. (299)
Darwin’s obsession with endemism while on the Beagle, and his consequent focus on higher animals, may have been inspired in part by reading these words.
This anonymously penned essay, as far as I am aware, is the first post-Lamarckian, post-Brocchian work to examine, and even to develop a bit further, the transmutational debate in terms of the search for natural causal explanations, patterns of transmutation (and biogeography), and putative causes underlying the origins and extinctions of species. Matched in scope only by Grant’s lecture of 1828 (published in 1829), this short paper (1826) in the Edinburgh New Philosophical Journal is a landmark in the history of evolutionary biology. It is impossible for me to imagine that Darwin somehow managed to miss it.
The fifth edition of Jameson’s translation of Cuvier’s Essay on the Theory of the Earth. With Geological Illustrations by Professor Jameson was published in 1827. As we have already seen, this book appears on the list of works Darwin “has read thro” since “my return to Edinburgh.” Though Jameson was no fan of Cuvier’s vision of multiple catastrophes wiping out most species in earlier faunas, replaced by newly created species as geological time wears on, he nonetheless admired the man and his work, manifestly enough to prepare successive editions in which presumably the main additions were in his own “geological illustrations.” And Jameson added a lot to the geological illustrations for this new, fifth, and final edition of Cuvier.
At first glance, the reader looking for signs of transmutational thinking in Jameson’s geological illustrations is apt to be a bit disappointed. Nothing like the clear, ringing declarations of “Observations on the Nature and Importance of Geology” (1826) present themselves in nearly as much depth, scope, and intensity—with the exception of two short passages. The first occurs in the preface to the fifth edition, hinting at transmutation, but also firmly linking Jameson to the anonymous essay “Observations on the Nature and Importance of Geology”:
Can it be maintained of Geology, which discloses to us the history of the first origin of organic beings, and traces their gradual development from the monade to man himself,—which enumerates and describes the changes that plants, animals, and minerals—the atmosphere, and the waters of the globe—have undergone from the earliest geological periods up to our own time, and which even instructs us in the earliest history of the human species—that it offers no gratification to the philosopher? Can even those who estimate the value of science, not by intellectual desires, but by practical advantages, deny the importance of Geology, certainly one of the foundations of agriculture, and which enables us to search out materials for numberless important economical purposes? (Jameson 1827b:vi–vii)
The first sentence is a pretty stark declaration of a natural causal process underlying the changes from “monades” to “man,” while the second sentence links Jameson firmly with “Observations on the Nature and Importance of Geology.”
The second passage on transmutation is a rather remarkable statement in the section “On the Universal Deluge.” Here we read:
These [physical geological] operations at the earth’s surface generally appear to have produced its present figure, and to have designed it for the habitation of numerous organic beings; This appears as early as a suitable element occurred; first in water, then in land animals; and, like the formation of rocks, we observe produced a regular succession of organic formations, the later always descending from the earlier, down to the present inhabitants of the earth, and to the last created being who was to exercise dominion over them. (431)
Again, pretty stark, as Jameson transforms a generalized statement of the geological succession from simple to complex into a declaration of transmutation—with the simple yet unmistakable phrase “the later always descending from the earlier, down to the present inhabitants of the earth.” That the advent of the modern fauna is a key to his thinking is thereby made especially plain, though Jameson pulls his punches a trifle when he refers to human beings as having been “created.”
The next sentence is also arresting, if for no other reason than it also seems to confirm the suspicion that Jameson was indeed the author of “Observations on the Nature and Importance of Geology.” Jameson writes: “But here occurs this important distinction: the organic world, with youthful vigour, renews itself daily, and decomposes its materials only to reunite them by fresh combinations in uninterrupted succession; while the powers of the inorganic world appear almost extinguished” (431).
This is the very same contrast between the dynamism and progressive changes in life through time contrasted with the immanence, sameness, and non-progressive aura of the physical history of the earth. Jameson does allude, several sentences earlier, to the effect that “new elements” (meaning water, first, then dry land) had on life, where the inorganic world seems to set the stage for changes in the succession of life. Despite this slight inconsistency, the distinction between the inorganic and organic histories of the earth, mentioned in these two successive publications, strongly suggests that Jameson was the author of both.
As far as Jameson’s text per se is concerned, though, that’s it for transmutational themes in Essay on the Theory of the Earth. With Geological Illustrations. But as it turns out, that is by no means the only material of direct transmutational import to be found in these pages. Jameson (Jameson 1827b:547–550), in fact, saved the best, literally, for last: just before we read “The End,” there are two remarkable tables (“tabular views”), the first taking up three pages, the second only one (figure 1.3). They amount to the first quantitative analysis of the fossil record since Brocchi published his observations on the percentages of living species of mollusks known from the fossil record.
The first table is “The Genera of Fossil Mammifera, Cetacea, Aves, Reptilia and Insecta,—exhibiting their Geognostical Number and Distribution.” The genera are listed down the left-hand column. Then there are six vertical columns: genera that are found (1) living only; (2) living and in the fossil state; (3) fossil only; (4) in the Strata anterior to the Chalk; (5) in the Strata of the Chalk; and (6) in the Strata posterior to the Chalk. Then there are two more columns: Number of Species (1) in the Living State (he makes no entries here) and (2) in the Fossil State; Jameson concludes the table with a column for miscellaneous observations.
The “table of genera” makes it obvious at a glance that many genera of the tabulated groups occur in the fossil as well as the living “state,” and that most of these occur in Tertiary sediments (that is, “posterior to the Chalk,” which is Cretaceous in age). There is in general a clear pattern of progressive modernization of the fauna as one approaches the “Recent.” That this pattern is a function of descent (species within genera) is implicit, and certainly borne out by the brief passage on descent in the text itself.
The second table lists the genera that are found in higher taxa (“Classes, Orders, or Families”) in the same columnar organization of geological occurrence as in the first table. For the univalved and bivalved mollusks, as well as the mammals and Cetacea (whales—which are of course mammals), most of the genera found as fossils are, again, Tertiary in age, though the “lower” orders of animals display less of a pattern of progressive modernization of the fauna as one ascends the stratigraphic column.
FIGURE 1.3 Robert Jameson, “The Genera of Fossil Mammifera, Cetacea, Aves, Reptilia and Insecta” and “The Classes, Orders, or Families, of Animals, occurring in a Living and Fossil State.” (From Essay on the Theory of the Earth. With Geological Illustrations by Professor Jameson [1827b:547–550])
Jameson does not discuss these results in the text, or even allude to them, as far as I can find. But someone, again almost undoubtedly Jameson, does in fact utilize these data in the second anonymous transmutational essay, again in the New Edinburgh Philosophical Journal, published in the same year as Jameson’s fifth edition of Cuvier: 1827. Its title: “Of the Changes Which Life Has Experienced on the Globe.”
The very first paragraph contains, as far as I have been able to ascertain, the first explicit usage of the imagery of new species replacing older extinct ones: the author writes “new animals and vegetables have assumed the place of those that have been destroyed and whose ancient existence is only revealed to us by their fossil remains” (Jameson 1827c:298). This imagery soon took center stage as the pattern to be explained by natural (secondary) causes in the British literature.
And the advent of the modern fauna is also well represented here: “As we approach nearer to the present time, we find in all places remains more and more resembling those of the plants and animals which now live in the same country” (299). Note how endemism is again a part of the mix when it comes to comparing fossil species with those of the “Recent.”
Going on to discuss changes in biogeographic distribution, the author of this little piece also says that physical changes in fact contribute to extinctions: “The beings, which were unable to resist the influence of these various causes were destroyed and disappeared from the earth, with the circumstances for which they were created; new species appeared with new conditions of existence” (300). And then, in what must have been a direct reference to Jameson’s tables, he writes:
But, in examining the series of fossils that are found buried in the strata of the globe, there is nowhere perceived a distinct line of demarcation between the different terms of that series, so as to prove that life has been once or oftener totally renewed on the earth. On the contrary, we discover in it a proof of the successive and gradual change which we have pointed out. Certain primitive types have indeed completely disappeared, but they are found existing at various epochs, and their remains are blended with those of more modern types; along with new species of types still existing, we find some of anterior epochs; certain genera that yet obtain are common to all the terms of the series; and toward the end of the series, we find the remains of some of our present species along with ancient types and extinct species. (300)
It is very much as if the author of “Of the Changes Which Life Has Experienced on the Globe” had Jameson’s tables in front of him when he wrote this passage. And that he sees in these data irrefutable proof that Cuvier’s ideas on multiple mass extinctions and subsequent wholesale reinvention of life are wrong is clear also from his conviction that his “theory, which has been founded on all the facts that have been established, cannot but prevail over the systems hitherto proposed.”
Then there is the more celebrated and better-known Robert Grant. Darwin’s ([1876] 1950) passage on Grant in Autobiography is well known: “He [Grant] one day, when we were walking together, burst forth in high admiration of Lamarck and his views on evolution. I listened in silent astonishment, and as far as I can judge without any effect on my mind. I had previously read the Zoonomia of my grandfather, in which similar views are maintained, but without producing any effect on me” (21).
Just as he did for Jameson, Darwin uses this almost mantra-like repetition of “no effect,” as he seeks to minimize the influence of both his grandfather’s and his mentor Grant’s evolutionary views. But he does go on to say in the very next sentence: “Nevertheless it is probable that hearing rather early in life such views maintained and praised may have favoured my upholding them under a different form in my Origin of Species” (21).
In other words, Darwin finds he can’t deny some kind of influence on him in his grandfather’s work (indeed, in his grandfather’s previous stature as England’s most outstanding, even notorious, evolutionist) and in the words and research program of his mentor Robert Grant. Though he was a medical doctor, Grant had been trained in invertebrate zoology in Paris, although not by Lamarck. That his work is distinctly transmutational lies in the fact that he was searching for connections between the plant and animal kingdoms. Indeed the very word “bryozoan” means “moss animals,” in spite of the fact it was known before the 1820s that these minute colonial organisms are clearly animals; Grant also used the word “zoophyte” (“animal plant”) regularly.
But the hallmark of Grant’s Lamarck-infused research was the search for anatomical intermediacy between different groups of species, genera, or even higher taxa: for example, in the paper naming the new genus Cliona, Grant (1826) claimed that the combination of characters present in Cliona provided the missing connection between Alcyonium (a cnidarian) and sponges.
Darwin “often” went to the shoreline of the Firth of Forth on the northern outskirts of Edinburgh with Grant. They were collecting marine invertebrates, and Darwin’s own research was on the bryozoan Flustra. Grant taught Darwin how to use a light microscope, and Darwin made some novel observations on what they thought was the “ova” (in reality, the larvae) of these bryozoans. Darwin discussed these results at a meeting of the Plinian Society. Writing in Autobiography, Darwin ([1876] 1950) said: “The papers which were read to our little society were not printed, so that I had not had the satisfaction of seeing my paper in print; but I believe Dr. Grant noticed my small discovery in his excellent memoir on Flustra” (22). In other words, Grant ripped Darwin off, publishing Darwin’s observations without crediting his young disciple. And I think it likely that it was on one of these excursions to the Firth of Forth that Grant “burst forth” in his paean of praise of Lamarck.
The Firth of Forth means something to me, as it ranks now to have been the second time that I crossed paths with Charles Darwin. I was to start chasing him down in earnest only in the first decade of the twenty-first century, after I had become involved in developing the exhibition Darwin, Discovering the Tree of Life—and thereby becoming so hooked that I had to pursue him in Great Britain and in South America.
We went out to the Firth of Forth with our host Euan Clarkson on a pleasant weekend excursion to collect Carboniferous fossil shrimp along the shoreline. We were in a mixed group of amateurs and professionals. Among us was the by-then-elderly Robert Watson-Watt, who invented radar during World War II. Watson-Watt sported a three-piece heavy mustard-colored tweed suit and spats—rather formal attire for such a shoreline experience, especially as the day was rather warm for those seaside Edinburgh climes. We were lucky indeed to have met Watson-Watt, as he died shortly thereafter at the age of eighty-one.
But once again, I had no idea at the time that Darwin had been there in the course of his training as a field zoologist, and under the guidance of an avowed adherent of Lamarck, whose own research focused on deep historical connections between such fundamentally disparate groups as plants and animals.
We ended that 1973 journey with a visit to London. Westminster Abbey was a don’t miss, and I found myself gazing at the slab covering Isaac Newton, the patron spirit of the entire enterprise of modern science, and especially of the search for natural causes for natural phenomena. But then I looked down, and found I was standing above Charles Darwin. Instantly there were tears in my eyes.
I had no idea Darwin was buried in Westminster. Many years later, in conjunction with doing that Darwin exhibition, I found out that Darwin had planned to be buried in the church cemetery in Downe Village, less than one mile from his house. But politics intervened. Darwin, as the Newton of evolutionary biology, could not have landed up in a more fitting place.
In any case, in Autobiography, Darwin dismisses Grant as having done nothing “more in science” after taking a position at the University of London in 1828—evidently not taking Grant’s inaugural address entitled “Essay on the Study of the Animal Kingdom” (1829) seriously. In fact, Grant’s essay is so beautifully fraught with Brocchi and Lamarck (though mentioning neither by name) that it must stand as one of the clearest and strongest exponents of a transmutational viewpoint published in England, with the exception of the earlier work of Darwin’s own grandfather, of course. Darwin does laconically acknowledge Grant’s notice of Darwin’s “small discovery in his excellent memoir on Flustra.” Whether his dismissal of Grant as a serious player in evolutionary thinking arose over that plagiarism flap, or simply from a desire to de-emphasize Grant’s importance on the development of Darwin’s own thinking, is impossible to judge.
Grant’s “Essay on the Study of the Animal Kingdom” (1829), the publication of the introductory lecture at the University of London (1828), is an understated, yet eye-opening gem in the early history of overtly published transmutational thinking in Great Britain. True, as Grant discusses the “succession” of animal species, he uses the word “created,” and goes out of his way in one particular passage to allude to the “Author of Nature.” The fiery, explosive words effusive in their praise of Lamarck, which one might have expected given Darwin’s report of Grant’s “outburst,” are basically missing here: this was, after all, a public lecture in the intellectually more staid environment of London. Grant was a very early faculty appointee in Great Britain, and he evidently chose his words carefully.
What we find, instead of a ringingly explicit proclamation of Lamarckian transmutation, is a measured description of the range of subject matter of zoology, including especially comparative anatomy and comparative physiology, but also biogeography, behavior, and even the human economic and philosophical interests attached to the animal world.
But the origins, nature of the histories, and extinctions of species are also here, as Grant (1829) writes:
This science [zoology] enquires into the origin and duration of entire species, and the causes which operate towards their increase or their gradual extinction; the laws which regulate their distribution, and the changes they undergo by the influence of climate, domestication, and other external circumstances. . . . It investigates the characters and relations of the extinct races of animals, the remains of which are found every where imbedded in the crust of the earth; and thus enables us to read, in their imperfect and mutilated remains, the history of the former inhabitants of this globe. It points out to us the order followed in the successive creation of animals, as discovered by their fossil remains, by their degree of organization, and by their relations to the strata of the earth, and unfolds the nature of those remarkable revolutions that have repeatedly taken place in the Animal Kingdom, in consequence of sudden or gradual changes in the condition of the surface of this globe. (6–7)
Grant’s rhetoric here is fraught with the search for “laws” and “causes” explicitly linked with everything on the history of species: their histories, the changes they undergo, and their eventual extinctions—everything but their origins. Yet we know from Darwin himself (and of course other evidence, including Grant’s empirical work) that he was in fact a transmutationist. One can only assume that on the very question of actual origins of species, Grant was doing the conventional thing by treading lightly; and indeed it is in the following paragraph that Grant does the obligatory genuflect to the “Author of Nature,” “to exalt our conceptions of the infinite wisdom, power and goodness of the great Author of Nature, as displayed in his minutest works.”
In other words, had Darwin not assured us of Grant’s fiercely held support of Lamarckian transmutation, it still might have been possible—though just barely so—to read Grant’s words cited earlier as not especially transmutational, if not downright creationist.
Nor is the passage purely Lamarckian in flavor, though the allusion to the “changes” that species undergo in the course of their histories is definitely reminiscent of Lamarck’s predicted pattern of the constant flux that species undergo through time. Rather, the passage has all the elements of the sort of hybrid vision of transmutation that was first developed in Jameson’s writings (assuming the two anonymous essays that had appeared shortly before were his), melding the births and deaths of species with evidence of continuity and change both within and among species.
Grant also alludes to the “constant warfare between the species”—ideas generally associated with the Frenchman de Candolle. From physiology to ecology, Grant is manifestly interested in dynamic, natural processes.
But it is in the passage that Grant indeed “bursts forth”—and what he writes is a brilliant synthesis of Brocchian and Lamarckian viewpoints: Brocchi’s analogy between the births and deaths of individuals and species is clearly here (though once again restricted to their deaths), and Grant (1829) tells us why Lamarck’s expectation of consistently smooth intergradations between species is in fact not observed, as he writes:
In this vast host of living beings, which all start into existence, vanish, and are renewed, in swift succession, like the shadows of the clouds in a summer’s day, each species has its peculiar form, structure, properties, and habits, adapted to its situation, which serve to distinguish it from every other species; and each individual has its destined purpose in the economy of nature. Individuals appear and disappear in rapid succession upon the earth, and entire species of animals have their limited duration, which is but a moment, compared with the antiquity of the globe. (11–12)
This is pure Brocchi. Grant is saying, despite his Lamarckian propensities, that species are discrete entities, and are adapted to their own “situation.” That means that every individual, as a representative of its species, plays a “destined” role “in the economy of nature.” Sticking with individuals, he then says that they “appear and disappear” in “rapid succession,” and jumps back up to the level of species: species themselves have their own “limited duration.”
Like Brocchi, Grant shies away from an explicit assessment of the analogy between the births of individuals and of species. Nor does he make clear the cause of the short durations (in the scale of geological time) of species. But the basic analogy between individuals and species is abundantly clear in this passage, and Brocchi’s fundamental “beautiful speculation” is unmistakably in print, in English, three years before Darwin set sail on the Beagle.
Grant (1829) continues:
Numberless species, and even entire genera and tribes of animals, the links which once connected the existing races, have long since begun and finished their career, and their former existence can now only be recognized by their skeletons, embalmed in the soft superficial strata of the earth, or by their casts preserved in the more solid rocks. . . . Almost every stratum [contain fossils that] the Zoologist must learn to decipher the history of the species, and discover their relations to the existing races. (11–12)
And there it is: all species (and “races”) were once connected. The reason we don’t find the Lamarckian “smear” of intergradation is that extinction has long since claimed those intermediates. It is the job of the “zoologist” (that is, paleontologist or, nowadays, “paleozoologist”) to discover these ancient remains and to “decipher” their relations with one another—and with the existing fauna. And though these words call to mind Grant’s well-publicized admiration of Lamarck, it must also be said that Brocchi would have had no objection to them either: in Brocchi’s lineages of ancestral and descendant species, the degree of anatomical differences between species was usually rather modest.
These two cited passages are in reality parts of a single, rather remarkable, modern-sounding paragraph. Use of the word “adapted,” the phrase “economy of nature,” the notion that species are indeed discrete entities with origins and eventual deaths (like individuals), and that all species and “races” were once interconnected, the skein only being broken by extinction, is as concise a characterization of the evolutionary history of life anyone (especially a paleontologist like myself) could ever hope to see. And these words were written in 1828—a culmination and integration, I think, of the transmutational ideas being developed and bandied about by those “Edinburgh Lamarckians”—especially Jameson and Grant.
There are further passages in which Grant reiterates the need to compare fossil species with living species, and by “pointing out the extensive and terrible catastrophes to which the Animal Kingdom has often been subjected,” thereby understanding a “cause of the many apparent interruptions in the chain of existing species”: his allegiance to Lamarck once again showing through, though once again Brocchi would not have objected. And while we have come to think of Grant strictly as a marine invertebrate zoologist (and there is indeed little evidence that he actually collected and analyzed fossils, or indeed delved into any other geological subject, on his own), nonetheless it was de rigeur for anyone braving the quest for a non-miraculous explanation of the origins of species in terms of material, natural (secondary) causes to address the fossil record and the connections between extinct and modern species simply in order to solve that cardinal question: How did modern species originate? Grant was no exception.
Giambattista Brocchi died in Egypt in 1826, and a brief notice of his passing was published—again anonymously, but again almost certainly written by Robert Jameson (1827a)—in the New Edinburgh Philosophical Journal. Brocchi is memorialized as “so well-known by his numerous works on geology and conchology” (383). Though nothing of Brocchi’s analogy and “beautiful speculations” is mentioned, the death notice is important simply in the fact that it is only the second time we know of that Brocchi’s name is mentioned in a British publication. That Jameson thought so highly of him is clear from the fact of the death notice itself.
One last, again anonymous, and once again undoubtedly Jameson-produced essay concludes this short review of the early transmutational literature centered in Edinburgh, mostly in Jameson’s own journal. The essay, published in 1829, is entitled “Of the Continuity of the Animal Kingdom by Means of Generation, from the First Ages of the World, to the Present Times” (subtitled “On the Relations of Organic Structure and Parentage That May Exist Between the Animals of the Historic Ages and Those at Present Living, and the Antediluvian and Extinct Species”). This is a short (3½-page) précis of a forthcoming “series of memoirs” by Étienne Geoffroy Saint-Hilaire “of which the first only has been read.”
The essay proclaims Lamarck to have been a genius ahead of his time—and also proclaims that Geoffroy’s experimental work proves that Lamarck was correct in asserting that transmutation occurs as a reaction to change in external circumstances. It is difficult to judge whether some passages are meant strictly to summarize Geoffroy’s views, or whether they do so, but with the anonymous author’s wholehearted agreement and approval.
Summarizing Geoffroy’s basic transmutational interpretation of the history of life, the author (Jameson [1829]) writes:
M. Geoffroy St. Hilaire believes in an uninterrupted succession of the animal kingdom, effected by means of generation, from the earliest ages of the world up to the present day. The ancient animals, indeed, whose remains have been preserved in the fossil state, are all, or at least almost all, different from those which now exist on the surface of the globe. But this is not a reason for thinking that they could not have been the ancestors of these latter. In the first place, the extinct species are united with the living species by the closest analogy. All have without difficulty entered into the prescribed limits of our great classifications; all, as being formed of analogous organs, seem to be nothing but modifications of the same being, of what is now called the vertebrate animal. (153)
This summary of Geoffroy’s views suggests that he (that is, Geoffroy) basically agreed with Lamarck that comparatively few species known as fossils are still to be found in the modern fauna; given the emphasis on vertebrates in Geoffroy’s work, this is hardly surprising. Yet Geoffroy used “mastodon” phylogeny to show that a progression of fossil and living species may belong to the same genera, as species of some genera of fossil elephants are still alive in the modern fauna. Jameson himself had (in 1827) already listed nearly thirty vertebrate genera known to be “living and in the fossil state.”
The anonymous author proceeds with his précis of Geoffroy’s views—this time pertaining to his older colleague Lamarck: “M. Geoffroy St Hilaire cited, as the performance of an author who outstripped the age in which he lived, the work in which M. de Lamarck treats Of the Influence of circumstances upon the actions and habitudes of living bodies, and, reciprocally, on the influence of the actions and habitudes of living bodies upon the modification of their parts” (154).
In what now seems to be as much the opinion of the anonymous author as it is of Geoffroy, we read that though Lamarck’s facts are not all trustworthy, his conclusions are undoubtedly true (“right for the wrong reason”): “The particular facts on which M. Lamarck rests his grand idea, are far from being perfectly correct. Perhaps there is not even one of them that is not blemished by some inaccuracy; yet the conclusion which he draws from them is true—such is the power of genius on foreseeing the great truths of nature.” But “to establish M. Geoffroy’s opinions in a solid manner, the important point is to demonstrate that the differences of atmospheric constitutions may have been sufficiently great and powerful to bring the different species and genera, from the types they originally presented, to what we now see them to be. Now, of this the author thinks no doubt can be entertained” (154).
First, consider the effects of introducing species into new geographic areas—new circumstance, new “atmospheric conditions.” Using data published, again in Jameson’s journal, by “Dr. Roulin with respect to the animals transported from Europe to America,” we see “the modifications which the species may still undergo, in consequence of a mere transportation from one latitude to another” (154).
But something more is required: experimental evidence on the production of monstrosities. We read that Geoffroy performed experiments on chickens, kept secret until now in a hostile political atmosphere, “to determine the power of external causes in modifying the development of living beings” (155).
And here, in what must be the anonymous author’s own conclusions on the significance of Geoffroy’s experimental work, we read: “The experiments here alluded to are conclusive. M. Geoffrey St Hilaire, by varying the phenomena of heat, dryness, and motion, not only produced monstrosities at pleasure, but even produced a given species of monstrosity, by means of a particular precaution” (155).
And the denouement: “And let it not be objected that the monstrous species thus produced in an artificial manner, were incapable of being reproduced and perpetuated. Nature, aided by time, which he had not at his disposal, acting by more numerous and gentler modifications, could have done what will always be impossible in the most judiciously conducted experiments” (155).
That Jameson (whether as author or simply as editor) is publishing here in 1829 such a ringing endorsement of the truth of Lamarck’s “grand idea” of transmutation, is in itself ringing testimony that transmutation was finally out of the closet as a subject to be discussed openly by the late 1820s—albeit still in anonymous authorship.
There is no evidence that Darwin ever read this short précis of Geoffroy’s work. By then he was long gone to Cambridge to take an undergraduate degree, en route to becoming a clergyman in the Church of England—though of course the Edinburgh New Philosophical Journal was available far beyond Edinburgh’s city limits. But there is plenty of evidence that Darwin’s interest in species and geology (despite what he later had had to say about Jameson’s lectures) if anything intensified while he was in Cambridge from 1828 to 1831.
CHARLES DARWIN IN CAMBRIDGE, 1828–1831
While Charles Darwin, acquiescing to his father’s desire to see him gain a profession after his “failure” at medical school, went to Cambridge for a general undergraduate degree with the nominal thought of eventually training for the clergy, he appears to have focused more on natural history than philosophy, literature, or religion. He continued his well-established habits of collecting specimens (mostly beetles) and participating in discussions of a scientific nature with many of the leading figures of the emerging professional science he met in Cambridge, among whom were John Stevens Henslow, Adam Sedgwick, William Whewell, and John Herschel. Sedgwick by then was already one of Britain’s most highly skilled and respected geologists. Whewell, a philosopher, had coined the very term “scientist,” and although he forever opposed ideas of transmutation, was very well read on this and all natural history subjects. Herschel, son of the famous astronomer William Herschel, was himself a scientist, but also a philosopher and a great thinker. He was an eloquent proponent of the search for natural causes for natural phenomena, which he felt was the central task of science, and yet certainly not antithetical to the observance of religion.
But it was John Stevens Henslow who was the main figure for Darwin. Henslow served for Darwin the same mentoring role as Grant did in Darwin’s second year at Edinburgh, after his older brother Erasmus had departed for London. Darwin became known as “the man who walks with Henslow,” frequently dining as well at the Henslow table.
There was one great difference between Darwin’s elders, teachers, and mentors at Edinburgh, and those he later met at Cambridge: in Edinburgh they had medical degrees. At Cambridge, most, including scientists such as Henslow and Sedgwick, were ordained clergymen. Little is known of the discussions with these men and others that Darwin was fortunate enough to take part in. But it seems a very safe bet that the radical ideas (including most certainly transmutation) that were so freely discussed, and often strongly supported, in Edinburgh were treated with great circumspection, if brought up at all, in those days in Cambridge.
Henslow had begun as a crystallographer, but had then accepted a professorship in botany, and, becoming a quick and enthusiastic study, founded the Cambridge Herbarium and the Botanical Gardens, and began giving lectures in botany. Darwin took his course three times—every year that he was there.
Of course there is no way of knowing what Henslow and Darwin discussed during all their meetings; a syllabus of Henslow’s botany course survives. But the greatest insight into what Henslow may well have taught Darwin resides in the 10,172 individual plants mounted by Henslow, his staff, and students, including Darwin, on 3,654 sheets preserved in the Cambridge Herbarium. These have been analyzed recently by a team consisting of Darwin historian David Kohn, botanists Gina Murrell and John Parker, and information specialist Mark Whitehorn (2005).
Henslow was clearly out to determine the limits of variation within stable species. That he saw species as inherently stable despite their internal variation has generally been assumed to reflect his creationist position—though transmutationists such as Robert Jameson and Robert Grant especially were aware of within-species variation as well. Just because someone saw species as inherently stable (Giambattista Brocchi, for example; Jameson, for another) did not automatically imply the person was a creationist. Whewell saw species as stable, and was an adamant creationist. But it was only Jean-Baptiste Lamarck (and later, apparently, Étienne Geoffroy Saint-Hilaire, and arguably Jameson in the end) among the transmutationists who saw species as non-stable, inherently variable, and changing entities though time and space. To see species as stable entities was not to automatically be someone who rejected transmutation.
Henslow’s Herbarium sheets show that he was equally aware of within-population species variation and geographic variation. There can be no doubt that this emphasis on variation played a big role in Darwin’s thinking, though probably more so in the years after he discovered natural selection (in 1838) than in his earliest transmutational forays, in which he stressed the births and deaths of species, paying relatively little heed to patterns of within-species variation. But there is absolutely no doubt that Darwin’s hands-on experiences collecting British plants in the field and laying them out on sheets to document variation deepened his experiences in empirical field and observational research, extending his earlier experiences with marine invertebrates with Grant, as well as his own work with beetles. What he privately made of the variation Henslow taught him to see is of course unknown.
Adam Sedgwick, who was to write one of the more scathing denunciations of the Origin of Species when Darwin at long last published his transmutational views in 1859, was also, ironically, instrumental in training the young man to make geological observations in the field, which would be critical to the emergence of Darwin’s initial ruminations on transmutation. Darwin was right to worry about what his older colleagues, including his teachers, would think of his transmutational ideas: the major reason, I persist in thinking, that Darwin was so reluctant to publish his evolutionary ideas.
In roughly a week, Sedgwick taught Darwin the rudiments of measuring the angles of bedding planes in sedimentary rocks, a critical first step in arranging the sporadically outcropping rocks of a region in ascending stratigraphic (hence chronological) order, thence paving the way for an interpretation of the sequence of events in the physical history of a region in the remote geological past. Darwin ([1832] 2008b) was later to write Henslow from the Beagle, asking him to convey his thanks to Professor Sedgwick for this absolutely invaluable training: “Tell Prof: Sedgwick he does not know how much I am indebted to him for the Welch [sic] expedition” (129). Apparently, Sedgwick trusted Darwin’s observational skills so highly that the two entered into spirited discussions, often disagreeing on their interpretations of the geological history of that part of Wales they were visiting: a sign of great respect from the learned Professor Sedgwick.
As critically important as these experiences with the Reverends Henslow and Sedgwick undoubtedly were, there was one more circumstance that must have played an important role in shaping the course of Darwin’s intellectual life: he read Herschel’s A Preliminary Discourse on the Study of Natural Philosophy (1830). Considered by some to be the first modern statement of the nature and practice of science, the book amazed me. Following Herschel’s plea not to regard science (344; though Whewell had not yet coined the term “scientist”) as antithetical to religion, but simply as a rational way of understanding and explaining natural phenomena, Herschel then gives a thoroughly modern-sounding (to my non-philosopher’s ear, in any case) account of how science is done: basically what has come to be called the “hypothetico-deductive method” (figure 1.4)
FIGURE 1.4 John Herschel. (By permission, Library of Congress, Prints and Photographs Division)
Herschel presents scientific laws as invariant and eternal. Speaking of the combining of chemical elements, he says that “no chemist can doubt that it is already fixed what they [the elements] will do when the case does occur. They will obey certain laws, of which we know nothing at present, but which must be already fixed, or they could not be laws. It is not by habit, or by trial and failure, that they will learn what to do.” Herschel saw laws starkly: If A, then B. No room for trial and error—the attitude that led him (it was rumored to Darwin) to pronounce natural selection as the “Law of Higgledy-Piggledy” once the Origin of Species appeared in 1859. Given the importance of Herschel as one of the main inspirations to pursue a career in science, this must have been a cruel and crushing blow.
The remainder of Herschel’s book is an account of how natural philosophy sees the world, as of 1830. I was, in my naïveté, stunned to read “that, in one second of time, light travels over 192,000 miles”—surprisingly close to the modern figure. But it is what Herschel has to say on the history of life, and the patterns of resemblance linking up the species of the modern biota, that are most germane to understanding the influence Herschel had on the young Darwin. For though, in the early pages, Herschel says that “to ascend to the origin of things, and speculate on the creation, is not the business of the natural philosopher” (that is, science cannot know the ways of God), he does nonetheless boldly state the modern, scientific understanding of the modernization of the fauna right up to the origin of present-day species. This passage, on the fossil record, clearly embraces a vision of continuity of descent within lineages, and replacement of old species by new, à la Brocchi, Jameson, and Grant:
These remains [fossils] are occasionally brought to light; and their examination has afforded indubitable evidence of the former existence of a state of animated nature widely different from what now obtains on the globe, and of a period anterior to that in which it has been the habitation of man, or rather, indeed, of a series of periods, of unknown duration, in which both land and sea teemed with forms of animal and vegetable life, which have successively disappeared and given place to others, and these again to new races approximating gradually more and more nearly to those which now inhabit them, and at length comprehending species which have their counterparts existing. (283)
It couldn’t be more clear, really, that Herschel (like everyone else, omitting citation) was repeating the conclusions, and even the language, of the radical thinking in Edinburgh. As to the modern fauna, considered alone, Herschel (1830) writes that “the great progress which has been made in comparative anatomy has enabled us to trace a graduated scale of organization almost through the whole chain of animal being; a scale not without its intervals, but which every successive discovery of animals heretofore unknown has tended to fill up” (290). A tip of the hat, perhaps, to Lamarck, though no one, including Brocchi, would have disagreed.
And before turning to Darwin’s epochal experimental transmutational work on the Beagle, let us not forget that famous line from Herschel’s letter to Charles Lyell written in February 1836, not to be seen by Darwin until the letter was published in 1838 (though he may have discussed the same points when he met Herschel in Cape Town in June 1836). This letter was written long after Darwin had not only sailed, but (as we shall soon see) had long since developed his own transmutational ideas (no later than February 1835—but in my opinion several years earlier). Obviously, then, Herschel’s words to Lyell could have had “no effect” on the actual development of Darwin’s views—beyond, that is, cheering him on when he read the words and noted them in Notebook E, and later resurrected them in the second sentence of the Origin of Species. But the passage is instructive, as it leaves little doubt that Herschel was almost certainly thinking that natural rather than miraculous processes underlie the origin of species when he wrote the passage, cited earlier, in Preliminary Discourse on Natural Philosophy (1830)—the passage Darwin must have read.
In the more complete quote, Herschel writes to Lyell:
Of course I allude to that mystery of mysteries, the replacement of extinct species by others. Many will doubtless think your speculations too bold, but it is well to face the difficulty at once. For my own part, I cannot but think it an inadequate conception of the Creator, to assume it as granted that his combinations are exhausted upon any one of the theatres of his former exercise, though in this, as in all his other works, we are led, by all analogy, to suppose that he operates through a series of intermediate causes, and that in consequence the origin of fresh species, could it ever come under our cognizance, would be found to be a natural in contradistinction to a miraculous process—although we perceive no indications of any process actually in progress which is likely to issue in such a result.” (quoted in Babbage 1838:225–227; see also Kohn 1987:413n.59-2)
Only Lamarck had offered a natural causal process (and by 1829 Jameson, citing Geoffroy, had agreed), and that was not for the replacement of species by “fresh” species, but through the steady modification of one species transforming it into an apparent descendant. But for those, beginning with Brocchi, who saw the problem as replacement of extinct, stable species by descendant “fresh” species, no one had yet proposed a mechanism—and were not to do so until Darwin, safely home from the Beagle voyage, did so in 1837, in Notebook B. Contrary to what one might imagine, that causal, theoretical explanation was not natural selection. It was, instead, geographic (“allopatric”) speciation.
Time now to look at how Darwin did that.
