The Story of Western Science

by Susan Wise Bauer

  Life . . . is an order and state of things which permit of organic movements; and these movements . . . result from the action of a stimulating cause which excites them. . . . Living beings . . . possess, as everyone knows, the faculties of alimentation, development, [and] reproduction, and they are subject to death.5

  In other words, all living things have movement that originates from within. They also respond to outside stimuli by changing and shifting. And, perhaps most of all, they die.

  So the study of biology (the logos, word, about bios, all living things) did not have the luxury of ignoring beginnings and ends—unlike geology. Movement is change; birth is change; death is change. The biologist could not simply describe. He had to explain the presence, and purpose, of change.

  Lamarck proposed three principles of change.

  The first, the “principle of use and disuse,” incorporated decay and death into the forward progress of life itself. Returning to the idea that the history of the earth and the history of life are intertwined, Lamarck theorized that living creatures transform as they respond to shifts in the earth itself:

  The continued use of any organ leads to its development, strengthens it and even enlarges it, while permanent disuse of any organ is injurious to its development, causes it to deteriorate and ultimately disappear if the disuse continues for a long period through successive generations. Hence we may infer that when some change in the environment leads to a change of habit in some race of animals, the organs that are less used die away little by little, while those which are more used develop better, and acquire a vigour and size proportional to their use.6

  Small changes in the environment lead to small changes in life; “a great and permanent alteration in the environment . . . induces new habits,” which over time produce great changes.

  Second, these alterations happen over great periods of time and are brought about by no agency apart from nature itself. Like Hutton, twenty years before, Lamarck rejected the possibility of ancient deluges and comets: “But why are we to assume . . . a universal catastrophe,” he writes, “when the better known procedure of nature suffices to account for all the facts which we can observe?”

  With regard to living bodies . . . nature has done everything little by little and successively. . . . In all nature’s works nothing is done abruptly, but . . . she acts everywhere slowly and by successive stages. . . . There is no necessity whatever to imagine that a universal catastrophe came to overthrow everything, and destroy a great part of nature’s own works.

  He acknowledges the part that a “Supreme Author” must have played at the beginning of all things, but insists that this “infinite Power” designed nature to carry out change without further divine interference: “Nature herself,” he writes, “has created organisation, life, and even feeling. . . . Nature possesses the necessary powers and faculties for producing herself.”7

  And finally, all of this change has a particular direction—from the simple to the complex, from lesser to greater, from primitive to the most advanced. Life began, long ago, in water and in simplicity, and then evolved forward:

  Water is the true cradle of the entire animal kingdom. . . . It is exclusively in water or very moist places that nature achieved . . . those direct or spontaneous generations which bring into existence the most simple organized animalcules, whence all other animals have sprung in turn. . . . After a long succession of generations these individuals, originally belonging to one species, become at length transformed into a new species distinct from the first.

  This transformation turned simple, “imperfect” living bodies into “the most perfect . . . having the most complex organisation.” Loss, death, and decay had a purpose: nature’s path led, ultimately, to perfection.8

  It was a grand theory, but Lamarck was forced to argue for it on the traditional basis of internal consistency. His proposal wasn’t exactly open to experimental proofs; the best he could do was to put forward his observations that existing living creatures appeared to be perfectly adapted to their early environments, along with the certainty that the earth had changed enormously over time. The logical conclusion was, obviously, that living creatures had also changed enormously over time.

  The great weakness of the proposal was its missing mechanism. How did those changes get passed along from generation to generation? Lamarck had no idea (and neither did anyone else), so he was forced to rely on vague Platonic language about nature’s “will” to produce transformations. “Something that might amuse the imagination of a poet,” sniffed Georges Cuvier, who found the principle of use and disuse entirely ridiculous.9

  This missing mechanism ultimately doomed the theory; it drew more opposition than agreement, more scorn than acceptance. Lamarck, never in the top rank of French scientists either socially or by training, grew increasingly bitter over the reception of the Zoological Philosophy. He continued to defend it, but the frailty that had haunted him since his teenaged injury had progressed; his eyes were failing, he was soon unable to leave his house easily, and his mind increasingly circled around his failures. He had never been wealthy, and his savings shrank to nothing. His wife died. One of his sons had been born deaf and mentally disabled, and he was forced to confine another to an insane asylum. At his death, twenty years after the publication of his groundbreaking theory, Lamarck’s two surviving daughters were too poor to bury him properly; his body was deposited into a general pit that was cleared out every five years, with all the bones piled together in an underground catacomb. Today, his final resting place is unknown.

  He had been a little too far ahead of his time, a little too grand in his scheme, a little too dismissive of the need for physical evidence. But he provided a pattern for future biologists, an outline that every subsequent natural historian would build on: the first coherent narrative about the history of life. Fifty years later, the prominent biologist Ernst Haeckel—supporter and popularizer of Charles Darwin, and a best-selling author in his own right—finally provided Jean-Baptiste Lamarck with a proper elegy: “To him will always belong the immortal glory,” Haeckel concluded, “of having for the first time worked out the theory of descent, as an independent scientific theory of the first order, and as the philosophical foundation of the whole science of biology.”10

  To read relevant excerpts from the Zoological Philosophy, visit http://susanwisebauer.com/story-of-science.

  JEAN-BAPTISTE LAMARCK

  Zoological Philosophy

  (1809)

  Lamarck’s prose style is clear but repetitive; the Zoological Philosophy is about five times as long as it needs to be. You can grasp the basics of his argument by reading the Preface, Preliminary Discourse, Chapters 1–4 and Chapter 7 of Part I, and Chapters 1 and 2 of Part II.

  The 1914 translation by Hugh Elliot is still standard. It is widely available as an e-book and has also been reprinted (in an exact replication of the e-book) as a paperback by Forgotten Books.

  Jean Baptiste Lamarck, Zoological Philosophy: An Exposition with Regard to the Natural History of Animals, trans. Hugh Elliot, Macmillan (e-book, 1914; paperback reprint by Forgotten Books, 2012; no ISBN).

  * * *

  * The two-continent war had at least two names; the European fight is generally known as the Seven Years’ War, while the North American conflict is more usually called the French and Indian War or the War of the Conquest.

  TWENTY

  Natural Selection

  The first naturalistic explanation for the origin of species

  Species have changed, and are still slowly changing by the

  preservation and accumulation of successive slight favourable

  variations.

  —Charles Darwin, On the Origin of Species, 1859

  The Zoological Philosophy, sweeping and comprehensive though it was, left a colossal question unanswered.

  From “the most simple organized animalcules,” Lamarck had written, “all other animals have sprung in turn.” But how did this happen? Had all
species on earth sprung from a single kind? If so, what prompted them to divide and differentiate? And for that matter, what was a species?

  This wasn’t a simple question. Lamarck, more interested in life itself than in its subdivisions, had skirted it with a one-line definition (“Any collection of like individuals which were produced by others similar to themselves”). But in this, he was not out of line with his contemporaries. No natural historian, from Aristotle on, had really offered a satisfactory definition of species—or a coherent explanation of how different species came to be.1

  Aristotle had grouped animals together using several different criteria—anatomy, diet, and (most of all) habits. His “species” were separated by the ways in which each one had adapted to a specific manner of life. So his divisions were complicated and overlapping: aquatic and nonaquatic, with feet and without feet, stationary and free, bloody and bloodless.2

  Medieval efforts to classify living things tended to follow this pattern by grouping plants and animals together by their structure, or appearance, or habits, or all three simultaneously. “Plants are divided into three groups,” writes Abu al-Dinawari, in the ninth-century Book of Plants:

  In one, root and stem survive the winter; in the second the winter kills the stem, but the root survives and the plant develops anew from this surviving rootstock; in the third group both root and stem are killed by the winter, and the new plant develops from seeds scattered in the earth. All plants may also be arranged in three other groups; some rise without help in one stem, others rise also but need the help of some object to climb, whilst the plants of the third group do not rise above the soil, but creep along its surface and spread upon it.3

  Seven hundred years later, the English naturalist Thomas Moufet was still making use of the same imprecise methods to “classify” insects. “Some are green, some black, some blue,” he wrote, in the Theatrum insectorum. “Some fly with one pair of wings, others with more; those that have no wings they leap, those that cannot either fly or leap, they walk; some have longer shanks, some shorter. Some there are that sing, others are silent.”4

  But as the sixteenth century gave way to the seventeenth, explorers ranged farther and farther into unfamiliar lands; colonists farmed strange grounds and hunted exotic animals through unknown forests; and the relatively small number of known animals, plants, and insects exploded into a panoply of varieties. A better method of organization was needed—along with a more reliable system of dividing all of that organic abundance into groups.

  In 1735, Carolus Linnaeus’s Systema naturae made the first truly scientific attempt to classify living things. After this first version of Systema naturae came out, Linnaeus, a Swedish physician and botanist, revised and reworked it for thirty years, publishing the twelfth revised edition not long before his death. He followed medieval custom by grouping plants into one kingdom, animals into another, and minerals into a third (a division still preserved for us in the game Twenty Questions). But his taxonomy departed from medieval practice in its precision and rigor: every living creature was assigned, on the basis of its morphology (form or shape), into a single genus, a single order, and a single class.

  Despite its groundbreaking precision, the Systema naturae shared with Aristotle, and with every other natural historian who had tried to put living things into categories, the most basic of assumptions: Species were different.

  For Aristotle, they were essentially different, separate in their very being. Medieval thinkers agreed. A species, according to Augustine of Hippo, was similia atque ad unam originem pertinentia, “similar and of a single origin,” each one created individually and apart from the other. Linnaeus’s species are just as static: “We count as many species,” he writes, “as different forms were created in the beginning.” Even Lamarck, for all his talk of simple animalcules developing into more complex ones, seems to have had in mind a whole array of simple animalcules, each brought to life by spontaneous generation and then developing into its own more complex forms.5

  Species did not develop from each other. They were, as Ernst Mayr put it, fixed, permanent, and bridgeless. And the precision of Linnaeus’s classifications only cemented this belief more firmly into place.

  •

  Three decades after Linnaeus’s death, Charles Darwin was born in Shropshire, England, the fifth child of a prosperous physician. It was 1809; the intermittently mad George III ruled Britain, in spells; Jean-Baptiste Lamarck had just published the Zoological Philosophy, James Hutton’s uniformity was slowly enfolding Bishop Ussher’s young earth, and Georges Cuvier was hard at work drafting his alternative theory of catastrophes.

  “I was a born naturalist,” Darwin later remarked; his childhood was devoted to collecting, fishing, tracking, and reading natural history. But his father sent him first to the University of Edinburgh to study medicine, and then to Cambridge, hoping to launch him into the church. Neither field interested him (“my time was wasted,” he wrote, “I was . . . sickened with lectures”) and he did more riding than studying, more bird-watching than Greek. “No pursuit at Cambridge,” he recollected, “gave me so much pleasure as collecting beetles.”6

  Darwin finished school in 1831 with a decent degree, an encyclopedic knowledge of the natural world, and absolutely no interest in either healing or preaching. But he had impressed several of his Cambridge professors with his extracurricular studies. One of them, the botanist John Henslow, recommended him to another acquaintance, naval officer Robert Fitzroy, as the perfect addition to Fitzroy’s upcoming expedition—a two-year sea voyage that would take a complete geographic survey of the South American coast.

  Darwin accepted at once. The planned Christmas departure of Fitzroy’s ship, the HMS Beagle, was delayed when the entire crew got sloshed: “A beautiful day,” Darwin recorded in his diary on December 26, “& an excellent one for sailing—the opportunity has been lost owing to the drunkedness & absence of nearly the whole crew.” Finally, the Beagle set off from Plymouth Sound on December 27, 1831.7

  The two-year journey extended to five, and the Beagle continued from the South American coast to the Galápagos Islands, then to Tahiti and Australia, circling the globe before returning home. Darwin kept copious notes on his observations. Again and again, these notes describe his struggle with the problem of species.

  To start with, the whole concept of a species was still poorly defined. “No one definition has satisfied all naturalists,” Darwin wrote, a quarter of a century later, “yet every naturalist knows vaguely what he means when he speaks of a species.” And the fixity and permanence of species (whatever they were) required multiple acts of divine creation. So why were European ground beetles, Alpine cave beetles, and American cave fish all sightless? Had each of these species been created, separately, without sight? Turnips, rutabagas, and various gourds all had enlarged stems; should this be chalked up to “three separated yet closely related acts of creation”? Or perhaps these were not separate species, just varieties? But in that case, the present definitions of species were all drastically inadequate.8

  Darwin’s questions were only deepened by the vast variations of living creatures that he now saw. Each island of the Galápagos had its own mockingbird; they did not interbreed, and they differed in vital ways, so each might be considered a different species; yet they were also, essentially, alike. How should they be classified? What accounted for their differences, and (even more) their similarities?

  “When I was on board the Beagle,” Charles Darwin later wrote, “I believed in the permanence of species, but, as far as I can remember, vague doubts occasionally flitted across my mind. On my return home in the autumn of 1836 I immediately began to prepare my journal for publication” (the account would be published in 1839 as Journal and Remarks, although it is usually now known as The Voyage of the Beagle) “and then saw how many facts indicated the common descent of species, so that in July, 1837, I opened a note-book to record any facts which might bear on the question; but I did not become con
vinced that species were mutable until, I think, two or three years had elapsed.”9

  That notebook was only the first of a series; and all of them were filled with problems. In the notebook that Darwin created between July 1837 and February 1838, he wrote, in part,

  Species are constant over whole country?

  Every animal has tendency to change.—This difficult to prove. . . .

  No answer because time short & no great change has happened.

  Unknown causes of change. . . .

  Each species changes. Does it progress?

  Changes not result of will of animal, but law of adaptation.

  There is nothing stranger in death of species than individuals.

  Difficult for man to be unprejudiced about self. 10

  While he was struggling with the species problem, Darwin was also reading the works of fellow natural philosophers: borrowing some of their principles, rejecting others. Charles Lyell had published the Principles of Geology just as Darwin was setting out on the HMS Beagle; “I had brought with me the first volume . . . which I studied attentively,” Darwin notes, “and the book was of the highest service to me in many ways.” He found Lyell’s long-and-slow philosophy of change entirely convincing and adopted it for his own (“Natura non facit saltum,” he wrote—Nature does not make sudden jumps) but disagreed with Lyell’s insistence that changes have no particular progression forward. Darwin read Lamarck’s Zoological Philosophy and appreciated Lamarck’s vision of adaptation leading toward more complex, more “perfect” forms—although he made vigorous marginal notes criticizing the theory of use and disuse. “It is absurd this way,” he scribbled, “he assumes the want of habit causes animals annihilation of organ and vice versa.”11

  In the fall of 1838, he picked up the most recent edition of Thomas Malthus’s best-selling Essay on the Principle of Population. Malthus, a professor of history and political economy at the East India Company’s training college for its administrators, had first published the essay in 1798, and had been refining it ever since. The future of the human race, Malthus argued, was shaped by two factors: