Ever Since Darwin: Reflections in Natural History
Page 3
Now Tory politics was not Fitzroy’s only ideological passion. The other was religion. Fitzroy had some moments of doubt about the Bible’s literal truth, but he tended to view Moses as an accurate historian and geologist and even spent considerable time trying to calculate the dimensions of Noah’s Ark. Fitzroy’s idée fixe, at least in later life, was the “argument from design,” the belief that God’s benevolence (indeed his very existence) can be inferred from the perfection of organic structure. Darwin, on the other hand, accepted the idea of excellent design but proposed a natural explanation that could not have been more contrary to Fitzroy’s conviction. Darwin developed an evolutionary theory based on chance variation and natural selection imposed by an external environment: a rigidly materialistic (and basically atheistic) version of evolution (see essay 1). Many other evolutionary theories of the nineteenth century were far more congenial to Fitzroy’s type of Christianity. Religious leaders, for example, had far less trouble with common proposals for innate perfecting tendencies than with Darwin’s uncompromisingly mechanical view.
Was Darwin led to his philosophical outlook partly as a response to Fitzroy’s dogmatic insistence upon the argument from design? We have no evidence that Darwin, aboard the Beagle, was anything but a good Christian. The doubts and rejection came later. Midway through the voyage, he wrote to a friend: “I often conjecture what will become of me; my wishes certainly would make me a country clergyman.” And he even coauthored with Fitzroy an appeal for the support of Pacific missionary work entitled, “The Moral State of Tahiti.” But the seeds of doubt must have been sown in quiet hours of contemplation aboard the Beagle. And think of Darwin’s position on board—dining every day for five years with an authoritarian captain whom he could not rebuke, whose politics and bearing stood against all his beliefs, and whom, basically, he did not like. Who knows what “silent alchemy” might have worked upon Darwin’s brain during five years of insistent harangue. Fitzroy may well have been far more important than finches, at least for inspiring the materialistic and antitheistic tone of Darwin’s philosophy and evolutionary theory.
Fitzroy, at least, blamed himself as his mind became unhinged in later life. He began to see himself as the unwitting agent of Darwin’s heresy (indeed, I am suggesting that this may be true in a more literal sense than Fitzroy ever imagined). He developed a burning desire to expiate his guilt and to reassert the Bible’s supremacy. At the famous British Association Meeting of 1860 (where Huxley creamed Bishop “Soapy Sam” Wilberforce), the unbalanced Fitzroy stalked about, holding a Bible above his head and shouting, “The Book, The Book.” Five years later, he slit his throat.
3 | Darwin’s Dilemma: The Odyssey of Evolution
THE EXEGESIS OF evolution as a concept has occupied the lifetimes of a thousand scientists. In this essay, I present something almost laughably narrow in comparison—an exegesis of the word itself. I shall trace how organic change came to be called evolution. The tale is complex and fascinating as a purely antiquarian exercise in etymological detection. But more is at stake, for a past usage of this word has contributed to the most common, current misunderstanding among laymen of what scientists mean by evolution.
To begin with a paradox: Darwin, Lamarck, and Haeckel—the greatest nineteenth-century evolutionists of England, France, and Germany, respectively—did not use the word evolution in the original editions of their great works. Darwin spoke of “descent with modification,” Lamarck of “transformisme.” Haeckel preferred “Transmutations-Theorie” or “Descendenz-Theorie.” Why did they not use “evolution” and how did their story of organic change acquire its present name?
Darwin shunned evolution as a description of his theory for two reasons. In his day, first of all, evolution already had a technical meaning in biology. In fact, it described a theory of embryology that could not be reconciled with Darwin’s views of organic development.
In 1744, the German biologist Albrecht von Haller had coined the term evolution to describe the theory that embryos grew from preformed homunculi enclosed in the egg or sperm (and that, fantastic as it may seem today, all future generations had been created in the ovaries of Eve or testes of Adam, enclosed like Russian dolls, one within the next—a homunculus in each of Eve’s ova, a tinier homunculus in each ovum of the homunculus, and so on). This theory of evolution (or preformation) was opposed by the epigeneticists who believed that the complexity of adult shape arose from an originally formless egg (see essay 25 for a fuller account of this debate). Haller chose his term carefully, for the Latin evolvere means “to unroll”; indeed, the tiny homunculus unfolded from its originally cramped quarters and simply increased in size during its embryonic development.
Yet Haller’s embryological evolution seemed to preclude Darwin’s descent with modification. If the entire history of the human race were prepackaged into Eve’s ovaries, how could natural selection (or any other force for that matter) alter the preordained course of our sojourn on earth?
Our mystery seems only to deepen. How could Haller’s term be transformed into a nearly opposite meaning? This became possible only because Haller’s theory was in its death throes by 1859; with its demise, the term that Haller had used became available for other purposes.
“Evolution” as a description of Darwin’s “descent with modification” was not borrowed from a previous technical meaning; it was, rather, expropriated from the vernacular. Evolution, in Darwin’s day, had become a common English word with a meaning quite different from Haller’s technical sense. The Oxford English Dictionary traces it to a 1647 poem of H. More: “Evolution of outward forms spread in the world’s vast spright [spirit].” But this was “unrolling” in a sense very different from Haller’s. It implied “the appearance in orderly succession of a long train of events,” and more important, it embodied a concept of progressive development—an orderly unfolding from simple to complex. The O.E.D. continues, “The process of developing from a rudimentary to a mature or complete state.” Thus evolution, in the vernacular, was firmly tied to a concept of progress.
Darwin did use evolve in this vernacular sense—in fact it is the very last word of his book.
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.
Darwin chose it for this passage because he wanted to contrast the flux of organic development with the fixity of such physical laws as gravitation. But it was a word he used very rarely indeed, for Darwin explicitly rejected the common equation of what we now call evolution with any notion of progress.
In a famous epigram, Darwin reminded himself never to say “higher” or “lower” in describing the structure of organisms—for if an amoeba is as well adapted to its environment as we are to ours, who is to say that we are higher creatures? Thus Darwin shunned evolution as a description for his descent with modification, both because its technical meaning contrasted with his beliefs and because he was uncomfortable with the notion of inevitable progress inherent in its vernacular meaning.
Evolution entered the English language as a synonym for “descent with modification” through the propaganda of Herbert Spencer, that indefatigable Victorian pundit of nearly everything. Evolution, to Spencer, was the overarching law of all development. And, to a smug Victorian, what principle other than progress could rule the developmental processes of the universe? Thus, Spencer defined the universal law in his First Principles of 1862: “Evolution is an integration of matter and concomitant dissipation of motion; during which the matter passes from an indefinite, incoherent homogeneity to a definite coherent heterogeneity.”
Two other aspects of Spencer’s work contributed to the establishment of evolution in its present meaning: First, in writing his very popular Principles of Biology (1864–67), Spencer constantly used
“evolution” as a description of organic change. Second, he did not view progress as an intrinsic capacity of matter, but as a result of “cooperation” between internal and external (environmental) forces. This view fit nicely with most nineteenth-century concepts of organic evolution, for Victorian scientists easily equated organic change with organic progress. Thus evolution was available when many scientists felt a need for a term more succinct than Darwin’s descent with modification. And since most evolutionists saw organic change as a process directed toward increasing complexity (that is, to us), their appropriation of Spencer’s general term did no violence to his definition.
Ironically, however, the father of evolutionary theory stood almost alone in insisting that organic change led only to increasing adaptation between organisms and their own environment and not to an abstract ideal of progress defined by structural complexity or increasing heterogeneity—never say higher or lower. Had we heeded Darwin’s warning, we would have been spared much of the confusion and misunderstanding that exists between scientists and laymen today. For Darwin’s view has triumphed among scientists who long ago abandoned the concept of necessary links between evolution and progress as the worst kind of anthropocentric bias. Yet most laymen still equate evolution with progress and define human evolution not simply as change, but as increasing intelligence, increasing height, or some other measure of assumed improvement.
In what may well be the most widespread antievolutionary document of modern times, the Jehovah’s Witnesses’ pamphlet ‘Did Man Get Here by Evolution or by Creation?” proclaims: “Evolution, in very simple terms, means that life progressed from one-celled organisms to its highest state, the human being, by means of a series of biological changes taking place over millions of years.… Mere change within a basic type of living thing is not to be regarded as evolution.”
This fallacious equation of organic evolution with progress continues to have unfortunate consequences. Historically, it engendered the abuses of Social Darwinism (which Darwin himself held in such suspicion). This discredited theory ranked human groups and cultures according to their assumed level of evolutionary attainment, with (not surprisingly) white Europeans at the top and people dwelling in their conquered colonies at the bottom. Today, it remains a primary component of our global arrogance, our belief in dominion over, rather than fellowship with, more than a million other species that inhabit our planet. The moving finger has written, of course, and nothing can be done; yet I am rather sorry that scientists contributed to a fundamental misunderstanding by selecting a vernacular word meaning progress as a name for Darwin’s less euphonious but more accurate “descent with modification.”
4 | Darwin’s Untimely Burial
IN ONE OF THE numerous movie versions of A Christmas Carol, Ebenezer Scrooge encounters a dignified gentleman sitting on a landing, as he mounts the steps to visit his dying partner, Jacob Marley, “Are you the doctor?” Scrooge inquires. “No,” replies the man, “I’m the undertaker; ours is a very competitive business.” The cutthroat world of intellectuals must rank a close second, and few events attract more notice than a proclamation that popular ideas have died. Darwin’s theory of natural selection has been a perennial candidate for burial. Tom Bethell held the most recent wake in a piece called “Darwin’s Mistake” (Harper’s, February 1976): “Darwin’s theory, I believe, is on the verge of collapse.… Natural selection was quietly abandoned, even by his most ardent supporters, some years ago.” News to me, and I, although I wear the Darwinian label with some pride, am not among the most ardent defenders of natural selection. I recall Mark Twain’s famous response to a premature obituary: “The reports of my death are greatly exaggerated.”
Bethell’s argument has a curious ring for most practicing scientists. We are always ready to watch a theory fall under the impact of new data, but we do not expect a great and influential theory to collapse from a logical error in its formulation. Virtually every empirical scientist has a touch of the Philistine. Scientists tend to ignore academic philosophy as an empty pursuit. Surely, any intelligent person can think straight by intuition. Yet Bethell cites no data at all in sealing the coffin of natural selection, only an error in Darwin’s reasoning: “Darwin made a mistake sufficiently serious to undermine his theory. And that mistake has only recently been recognized as such.… At one point in his argument, Darwin was misled.”
Although I will try to refute Bethell, I also deplore the unwillingness of scientists to explore seriously the logical structure of arguments. Much of what passes for evolutionary theory is as vacuous as Bethell claims. Many great theories are held together by chains of dubious metaphor and analogy. Bethell has correctly identified the hogwash surrounding evolutionary theory. But we differ in one fundamental way: for Bethell, Darwinian theory is rotten to the core; I find a pearl of great price at the center.
Natural selection is the central concept of Darwinian theory—the fittest survive and spread their favored traits through populations. Natural selection is defined by Spencer’s phrase “survival of the fittest,” but what does this famous bit of jargon really mean? Who are the fittest? And how is “fitness” defined? We often read that fitness involves no more than “differential reproductive success”—the production of more surviving offspring than other competing members of the population. Whoa! cries Bethell, as many others have before him. This formulation defines fitness in terms of survival only. The crucial phrase of natural selection means no more than “the survival of those who survive”—a vacuous tautology. (A tautology is a phrase—like “my father is a man”—containing no information in the predicate (“a man”) not inherent in the subject (“my father”). Tautologies are fine as definitions, but not as testable scientific statements—there can be nothing to test in a statement true by definition.)
But how could Darwin have made such a monumental, two-bit mistake? Even his severest critics have never accused him of crass stupidity. Obviously, Darwin must have tried to define fitness differently—to find a criterion for fitness independent of mere survival. Darwin did propose an independent criterion, but Bethell argues quite correctly that he relied upon analogy to establish it, a dangerous and slippery strategy. One might think that the first chapter of such a revolutionary book as Origin of Species would deal with cosmic questions and general concerns. It doesn’t. It’s about pigeons. Darwin devotes most of his first forty pages to “artificial selection” of favored traits by animal breeders. For here an independent criterion surely operates. The pigeon fancier knows what he wants. The fittest are not defined by their survival. They are, rather, allowed to survive because they possess desired traits.
The principle of natural selection depends upon the validity of an analogy with artificial selection. We must be able, like the pigeon fancier, to identify the fittest beforehand, not only by their subsequent survival. But nature is not an animal breeder; no preordained purpose regulates the history of life. In nature, any traits possessed by survivors must be counted as “more evolved”; in artificial selection, “superior” traits are defined before breeding even begins. Later evolutionists, Bethell argues, recognized the failure of Darwin’s analogy and redefined “fitness’ as mere survival. But they did not realize that they had undermined the logical structure of Darwin’s central postulate. Nature provides no independent criterion of fitness; thus, natural selection is tautological.
Bethel then moves to two important corollaries of his major argument. First, if fitness only means survival, then how can natural selection be a “creative” force, as Darwinians insist. Natural selection can only tell us how “a given type of animal became more numerous”; it cannot explain “how one type of animal gradually changed into another.” Secondly, why were Darwin and other eminent Victorians so sure that mindless nature could be compared with conscious selection by breeders. Bethell argues that the cultural climate of triumphant industrial capitalism had defined any change as inherently progressive. Mere survival in nature could only be for the good:
“It is beginning to look as though what Darwin really discovered was nothing more than the Victorian propensity to believe in progress.”
I believe that Darwin was right and that Bethell and his colleagues are mistaken: criteria of fitness independent of survival can be applied to nature and have been used consistently by evolutionists. But let me first admit that Bethell’s criticism applies to much of the technical literature in evolutionary theory, especially to the abstract mathematical treatments that consider evolution only as an alteration in numbers, not as a change in quality. These studies do assess fitness only in terms of differential survival. What else can be done with abstract models that trace the relative successes of hypothetical genes A and B in populations that exist only on computer tape? Nature, however, is not limited by the calculations of theoretical geneticists. In nature, A’s “superiority” over B will be expressed as differential survival, but it is not defined by it—or, at least, it better not be so defined, lest Bethell et al. triumph and Darwin surrender.
My defense of Darwin is neither startling, novel, nor profound. I merely assert that Darwin was justified in analogizing natural selection with animal breeding. In artificial selection, a breeder’s desire represents a “change of environment” for a population. In this new environment, certain traits are superior a priori; (they survive and spread by our breeder’s choice, but this is a result of their fitness, not a definition of it). In nature, Darwinian evolution is also a response to changing environments. Now, the key point: certain morphological, physiological, and behavioral traits should be superior a priori as designs for living in new environments. These traits confer fitness by an engineer’s criterion of good design, not by the empirical fact of their survival and spread. It got colder before the woolly mammoth evolved its shaggy coat.