The Molecular Shadow

George Gaylord Simpson is one of the most distinguished zoologists of the present day. He was the first to apply to paleontology the special blend of genetic and “population dynamical” thinking that most Americans learned from Dobzhansky, Mayr, and Sewall Wright, and most English students from Fisher, Haldane, and E. B. Ford. To zoologists of my generation, brought up on morphological abstractions and collections of old bones, Simpson’s Tempo and Mode in Evolution^* came as a revelation. The older zoologists could reconstruct an animal from its fossilized remains, but Simpson reconstructed populations of animals, and made us see how they might have responded to evolutionary forces of the same kind as those that shape the genetic structure of populations alive today.

In the old days evolutionary history was a narrative unfolded to us in the form of lantern slides or still pictures, one dynasty of organisms succeeding another/like the kings and queens of schoolroom histories. Simpson changed all that. His sense of biological history is profound, and the fact that the physical sciences are for the most part nonhistorical (“a snow crystal is the same today,” said D’Arcy Thompson, “as when the first snows fell”) marks for him one of the main distinctions between them and the sciences of living things.

It is to a man like Simpson (you’d think) that the humanist should turn if he wants to get an insight into how scientists think, and what they think about when they raise their eyes from the laboratory bench and contemplate the world around them. Here then is Simpson on the biological nature of man: it is a typical passage.

The question “What is man?” is probably the most profound that can be asked by man. It has always been central to any system of philosophy or theology…. The point I want to make now is that all attempts to answer that question before 1859 are worthless and that we will be better off if we ignore them completely.

The humanist will probably recover his composure by reflecting that the Man Simpson is talking about is Biological Man, not the poor old forked radish whose passions, frailties, and bewilderment have been under scrutiny these past few thousand years. But that is not what Simpson means. He is careful to point out that a full understanding of “essential man-ness or human nature” must call upon evidence from human behavior and psychology, and he therefore applauds Darwin for having discerned (in The Descent of Man) that man is a self-conscious and reflective being who moralizes and thinks abstractly, and has a sense of beauty and a feeling for religion; is a social animal, moreover, one who has “developed cultures and societies unique in kind and complexity.”

Does Simpson really believe that everything said on these matters before Darwin is worthless? I can find no evidence that he does not. Simpson on “Science and the Culture of our Time” is equally embarrassing. In my opinion it falls below the level that would justify serious critical attention. The interesting question is why Simpson should hold and apparently rejoice in his, to my mind, coarse and rancorous opinions. Perhaps his appraisal of Greek science holds the clue (“their so-called science was for the most part childish or ridiculous or both,” he tells us, and elsewhere he refers to the “Aristotelian nonsense” of the idea of First Causes). He seems to treat the Greek philosophers as the humanistic equivalents of fossils. But is it not a minor cultural paradox that a man whose sense of biological history was so acute as almost to bring fossils back to life should treat the Greeks and the older humanists as if they were a collection of old bones?

The more technically scientific parts of Biology and Man are marked by the same style of reasoning as those which (heaven help us) might be described as “cultural.” The opinions he disagrees with are described as silly, ridiculous, nonsensical, impossible, or inconceivable, but there is little in the way of sustained or critical argument between the rude noises. Simpson is enraged by the pretensions of molecular biology (“in my opinion nothing that has so far been learned about DNA has helped significantly to understand the nature of man or of any other organism”), yet molecular biology has thrown a flood of light on comparative anatomy itself, by reformulating its central concept, of homology, in precise analytical terms. It is true that he quotes some foolish opinions about molecular biology, but their folly does not make his opinions wise.

His main complaint about molecular biology, insofar as he understands its modern connotation (his reference to Wöhler’s mythical synthesis of urea suggests to me that he does not) is directed against its claim to uphold the canon of reducibility—roughly speaking the idea that everything about organisms or societies of organisms can be fully interpreted or explained by study of the lower elements of the compositional hierarchy.

In its molecular-biological form, the principle of reducibility declares that all the phenomena we think of as characteristically biological—heredity, memory, sexuality, fear and the like—will be reduced to, or interpreted according to, molecular structures and interactions. In its sociological form it states (as John Stuart Mill stated) that “the laws of the phenomena of society are, and can be, nothing but the laws of the actions and passions of human beings united together in the social state…. Human Beings in Society have no properties but those which are derived from, and may be resolved into, the laws of the nature of individual men.”

To use William Whewell’s figure of speech, emergence and reducibility are upstairs and downstairs on the same staircase. The principle of Emergence asserts that as we proceed upward from the molecular to the biological level and thereafter to societies of organisms, new concepts arise which cannot be interpreted or even expressed in the language or with the conceptual schemes of the lower analytical level. Though in a purely compositional sense societies are “made of” organisms, yet at the social level concepts emerge that are inexplicable in a language that has only to do with individual men, e.g. democracy, credit, and crime. The notions of reducibility and emergence cry out for thorough analysis, but we shall find no such analysis in Biology and Man. “Biology,” says Simpson, “is both reductionist and compositionist, both nonreductionist and noncompositionist”; but if this is so, why should these antitheses have come to be taken so seriously in his book, in Carl Pantin’s (which I now turn to), and in Marjorie Grene’s?

Carl Pantin was Professor of Zoology in Cambridge University from 1959 to 1966. His greatest single scientific achievement was to show that the nervous system of sea anemones and other simple creatures like them work to the same fundamental pattern as the nerves of higher organisms. In anemones as in vertebrates, he showed, nervous conduction is the propagation of a change of state powered by the nerve itself, and not a form of conduction that dies away in strength from the point of excitation. Pantin’s influence on the style and content of British zoology was very great, for he and his predecessor James Gray did more than anyone else to supplant comparative anatomy by comparative physiology as the core of the zoological curriculum. Like all other academic revolutions it hardened into an orthodoxy and became an abuse (as, one day, molecular biology will too), but in Pantin’s heyday it still had freshness and vigor and an important message to declare.

The greater part in The Relations between the Sciences consists of the Tarner Lectures, delivered in 1959 but subsequently revised. When Pantin died it was still not quite ready for press, but the two editors have added greatly to its value by helpful annotations and (most important) by completing his references.

Pantin was a learned, cultivated, and reflective man with a gentleness and sincerity that are evident in the whole style and structure of his book. He had a real gift for writing. Over and over again one is struck by felicities of expression and by his gift for pointed, relevant, and above all fresh quotations. All this may give the impression that the Tarner Lectures are to be written off as scientific belles lettres, but they are nothing of the kind. Pantin and Simpson go over much of the same ground—the problems of reducibility and purposiveness, the application of physical laws to living things, the diversity of organisms (as opposed to the uniformity of physical objects), and so on—but Pantin is understanding and conciliatory where Simpson so often adopts a threatening posture. There is the germ of a good idea in Pantin’s distinction between restricted and unrestricted sciences; it is to a deliberate restriction of vision, Pantin says, that the physical sciences owe their success. “Physics and chemistry have been able to become exact and mature just because so much of the wealth of natural phenomena is excluded from their study.” If Pantin had lived, I feel sure he would have worked his idea out more fully. At present it sounds as if he thought that the success of the physical sciences was the outcome of adopting restrictiveness as a methodological policy, which I am sure is incorrect: the confinement lies not in the act of looking but in actual area of the field of view.

Among the best things in The Relations between the Sciences are Pantin’s analysis of the history of the Towy river system, and his account (à propos of the Second Law of Thermodynamics) of the structure of a thunderstorm, chosen to show how a complex and improbable dynamic organization may grow up in a purely inorganic world which, considered as a whole, is moving in the direction of randomness and disorder.

Pantin quotes extensively from William Whewell and Stanley Jevons, and his “philosophy” is altogether in their style, as opposed to John Stuart Mill’s. He has no more use for the idea of “unprejudiced” observation than they had, and he gives a useful case history of the growth of one of his own ideas. I shall read Pantin again, parts of it more than once; I wish indeed I had had a chance to read it before embarking on a number of similar essays of my own.

To turn from Pantin to Marjorie Grene is to enter the dark and troubled intellectual underworld of Natur-philosophie. In Approaches to a Philosophical Biology Dr. Grene expounds the opinions of five nature-philosophers belonging to a continental tradition of thought: Adolf Portmann, Helmuth Plessner, F. J. J. Buytendijk, Erwin W. Straus, and Kurt Goldstein. Most working biologists in the English-speaking world will never have heard of them, and Dr. Grene suspects that not many are likely to try to make their acquaintance even now; yet two of them, she tells us, have expressed revolutionary opinions, and all have profoundly illuminating things to say on behavior, consciousness and Organism, and the essential character of life and being. Alas for me, I can find little in the writing except obscurely portentous explanatory concepts (e.g. Plessner’s “positionality”) or commonplace ideas distended with intellectual gas (e.g. Straus on the Dance).

Nature-philosophy must be the most ineffectual of all scholarly pursuits, and its practitioners always seem to me to have uncannily bad judgment. We remember J. B. S. Haldane’s declaring that no chemical substance could conceivably have the properties now known to be possessed by DNA; we remember the insistent and despairing advocacy of the evolutionary doctrines that came to be associated with the name of Lamarck, or the long-winded and inconclusive discussions of the antithesis between preformation and epigenesis. The advances of molecular biology have withdrawn these problems from the agenda of Naturphilosophie, which flourishes only upon what is not yet understood; and this process of attrition will continue until nothing of it remains except nostalgic recollections of the good old days when, because no one could say anything conclusive, almost everyone could have his say.

It seems to me hopeless to expect working biologists to take nature-philosophy very seriously. If it is to survive it must recruit a new audience from literary intellectuals who feel guilty about knowing next to nothing about biology, for as I argued in a recent Romanes Lecture (Encounter, January 1969) nature-philosophy belongs to a genre that has more in common with imaginative literature than with science. To say all this is not to question the strength of Dr. Grene’s own sense of concern about the direction of growth of modern biology, but only the means by which she hopes it may be set at rest.

The two volumes of Towards a Theoretical Biology represent the proceedings of two conferences held under the auspices of the International Union of Biological Sciences in the Villa Serbelloni, the Rockefeller Foundation’s scholarly asylum by Lake Como. The organizer and central figure, C. H. Waddington, is one of the most thoughtful and analytically skillful of modern biologists. Working in Cambridge before the war, he was one of the leaders of experimental embryology; after the war, with Cambridge unhappily dominated by comparative physiology, Waddington assembled and held together a group of young geneticists who made Edinburgh one of the world’s leading centers of genetic research.

For these symposia, Waddington convened an exceptionally intelligent, articulate and restless group of biologists and biological well-wishers (including, for the second conference, one other elder statesman—Ernst Mayr—and Dr. Marjorie Grene herself). The subject matter of the conference might be loosely defined as the “basic ideas” of biology, and the question of whether we might not one day devise a theoretical biology analogous to theoretical physics. How can the “evolutionary potential” of organisms be expressed in terms that go beyond the mere contribution of offspring to the immediately succeeding generation? Is Neo-Darwinism really satisfactory?—a question that can now be asked without one’s being suspected of trying to rehabilitate Lamarck. Can a computer be programmed to replicate itself? In what language and with what conceptual apparatus shall we describe the translation of genetic instructions into flesh and blood?

None of the people who tried to answer these questions was a molecular biologist in the modern sense, but molecular biology casts a shadow over the proceedings, at least insofar as they challenge its interpretative aggressiveness and its exuberant but unendearing self-confidence and self-sufficiency. These volumes may not inaugurate a theoretical biology (I do not myself think the putative analogy with theoretical physics is really sound) but they might well inaugurate a new and authentic style of scientific literature, for the contributions are thoughtful, imaginative, sometimes illuminating, and always a delight to read.

I end with two practical suggestions. The first is that all students of the Philosophy of Science should be required to read Grene on the one hand and Towards a Theoretical Biology on the other, whereupon they will become qualified to write confused and voluminous essays on the similarities and differences between the two. The second is that an enlightened Foundation should convene a small high-powered conference on the problem of reducibility, preferably run in the style in which Waddington ran his. If the four works reviewed above are anything to go by, it is the most challenging problem in the methodology of science today.