In the eighteenth century there was lively interest in Natural Theology: The essential arguments were brilliantly stated by David Hume in his Dialogues Concerning Natural Religion. Thirty years later came Paley’s Evidences of the Existence and Attributes of the Deity Collected from the Appearances of Nature. Its success was very likely responsible for the endowed Lectures which ensued—the Gifford, Lectures, “for Promoting, Advancing, Teaching, and Diffusing the Study of Natural Theology”; the Bridgewater Treatises “on the Power, Wisdom and Goodness of God, as manifested in the Creation”; the Silliman Lectures “designed to illustrate the presence and providence of God as manifested in the natural and moral world”; and others.

Professor Dubos, as Silliman Lecturer, is in the same tacit predicament as so many of his post-Darwinian fellow lecturers in these series: He extricates himself, as some of them have, by duly presenting the “appearances of nature” as scientific study has revealed them, and eschewing any inference at all about God’s attributes. The argument from design, for what it is worth, is left to speak for itself.

Adaptation, Dr. Dubos’s theme, is not new in this context. The first Bridgewater Treatise was on the Adaptation of External Nature to the Moral and Intellectual Constitution of Man; and the second dealt with the Adaptation of External Nature to the Physical Condition of Man. Dr. Dubos deals with the converse issue, man’s adaptation to the conditions of external nature. It is a significant transposition: Man is no longer viewed as central and determinant; he must change to fit his surroundings or he cannot survive. The thirty-ninth Silliman Lecture is an erudite, vigorous statement of the necessity for adaptation, its dangers and demands, and especially its medical implications.

Adaptation is a biological concept which has been extended into the social sciences, where it takes on a more diffuse meaning, and has as its aim not only survival but also improved function (including the functioning of social systems). Psychological and social factors have to be taken into account as much as biological ones. Thus the ability of human beings to learn widens enormously the range of adaptive responses, and at the same time creates conditions in which man’s adaptive responses become crucially necessary. Dr. Dubos does not trouble himself or the reader with definitions and niceties of approach, but goes straight into his thesis and expounds it with enthusiasm derived from intensive firsthand experience of relevant fields and an exceptional acquaintance with many branches of learning. He speaks of his own area of research when he describes the role of gastro-intestinal flora, and the development of immunity to tuberculosis.

AT THE OUTSET Professor Dubos makes some of his primary assumptions clear. The exact sciences tell us much about man’s nature in its physico-chemical aspects, but they fail to account for what is particularly human, the way in which our responses are determined by the symbolic interpretation we attach to stimuli when they are experienced. The problem of adaptation can be construed as a dialectic between what is lasting—man’s bodily and physiological constitution and his emotional drives—and what is changing (as his environment conspicuously is). Within these tensions man tries hard to develop adaptive systems—in which his personal choice of a goal may be decisive. His responses may not be directed at coping with the environment but at expressing himself creatively. The aim of medicine, however, has always been ideally to help man to cope with his environment adaptively. Medical scientists must look beyond the methods and problems of the natural sciences applied to the corporeal machine, and must, in common with other scientists, select their areas of preferred inquiry under the influence of social demands. Science, in short, must adapt itself to the changing conditions of the society in which it functions—a view pointedly urged by Lord Florey recently in his address to the Australian National University.

Professor Dubos is indisputably a humanist. He holds that physico-chemical models and evolutionary doctrines can not compass the actual problems of human life, and he quotes the pregnant remark of Paul Valéry: “L’homme n’est pas si simple qu’il suffise de le rabaisser pour le comprendre.” Far from wanting to lower and reduce man, Dubos exalts him: Man is unique, he has characteristics which set him apart from the rest of creation. Dubos seems to see man, indeed, as an “incomparable piece of work, noble in reason, infinite in faculty, the paragon of animals.”

The initial chapter of Man Adapting reviews the problem of adaptation entailed by our biological rhythms, extremes of climate, nutritional needs and opportunities, the varied interplay between living things, and the consequences of rapidly expanding population. All this is illustrated by specific examples, and made arresting by its authoritative pricking of bubbles. The indigenous microbiota (the innumerable micro-organisms that inhabit the digestive and respiratory tracts, and constitute part of the environment to which we have to adapt) provide a telling instance. The customary distinction between these and the organisms that cause disease “is arbitrary and usually meaningless…most micro-organisms commonly harbored by the body in the state of health are capable of exerting a wide range of pathological effects under special conditions. On the other hand many of the micro-organisms classified as pathogens, indeed probably all of them, often persist in vivo without causing overt disease.” The indigenous bacteria influence the rate of bodily growth in animals, and exert a protective effect against various forms of stress, such as malnutrition and infection; they can and do become pathological: If an animal is exposed to large doses of ionizing irradiation, organisms normally present in its intestinal tract multiply and cause septicemia. Physiological traits assumed to be the product of heredity are determined actually by the bacterial environment of the individual.


THE CONTROL of infectious diseases is commonly thought to have been so far achieved that research effort can now be safely switched from them to the degenerative diseases, cancer, and mental disorder. But great as has been the advance, the morbidity rates of infection have not lessened significantly: “There are many forms of infectious diseases that are not prevented or cured by sanitation, vaccines, or drugs.” Moreover, potentially harmful microbes may persist in the body without causing any symptoms or damage, until changes in the host or in the environment give them their license to become pathogenic. Epidemiologists and microbiologists between them have corrected the simple conception of infectious disease as arising solely because individuals or populations have been exposed to an external, pathogenic organism, and have shown how important are the genetic and immunological history of the affected persons, and changes in their nutrition, or in the equilibrium established between them and the micro-organisms normally housed in their bodies.

Professor Dubos naturally deals most fully with the problems and findings that have been the subject of his own researches, but his reading, his learning, and his discussions with other scientists—he acknowledges a particular debt to Dr. Walsh McDermott—have given the book balance and breadth. Social factors, he recognizes, play a large part in the causation and progress of disease. Psychological factors, likewise; the influence of emotion on physiological responses as well as on total behavior, the effects of suggestion, the therapeutic influence of dummy drugs, “placebos”—these examples of the relationship between mental and physical functions impress him, and with less than his usual caution he suggests that “as a working hypothesis, it might be useful to assume that one or a few common organic pathways account for healing agencies as different as psychoanalysis, ataractic drugs, Zen practices, Yogi meditations, witchcraft, a good vacation, and of course the proper physician-patient relationship.” There is much virtue in that “of course.”

No one could accuse Dr. Dubos of Panglossian complacency, but his optimism is great and cheering. Bearing in mind man’s untapped adaptive resources, he sees no limit—barring nuclear war—to the modifying social influences we can bring to bear on the external world, to fashion it nearer to our requirement. He rests his case largely on the historical evidence that men can adapt to utterly threatening ordeals and privations, and survive them. But, for the humanist, survival is not the ultimate criterion: “Human life involves values which have little to do with biological needs and which transcend the survival of individual persons.” Technological, medical, and social changes have to be dearly paid for, now or later: they interfere with natural selection; people with hereditary defects are kept alive and can reproduce: the population increases fast; mutation rates may be increasing too; and it may be—Dr. Dubos is properly hesitant here—that the physiological and psychological reactions evoked by efforts to adjust to emotional stresses caused by competition and crowding leave permanent scars on the mind. Man’s adaptability leads him to fit, without active resistance or with short-sighted acquiescence, into an environment which will sap beliefs and values most intrinsic to his human quality. In Dr. Dubos’s whole-hearted denunciation, “life in the modern city has become a symbol of the fact that man can become adapted to starless skies, treeless avenues, shapeless buildings, tasteless bread, joyless celebrations, spiritless pleasures—to a life without reverence for the past, love for the present, or hope for the future.”

WHILE PLEADING for urgent and sustained research into the influence of emotional states upon physiological and chemical activities in the body and upon conduct, Dr. Dubos sees very clearly that this will be most difficult because of the limited control which the investigator can exercise in any experiment and because of the irrational, willful element in human conduct. Reductionist analysis is incapable, from its nature, of accounting fully for integrated behavior.


The five final chapters of Man Adapting are concerned with medicine, and particularly with what its primary function and purpose should be. Health is here roundly called a mirage: Man can never be so perfectly adapted to his surroundings that he has no failures or sufferings. The paradox stares us in the face, that therapeutic medicine has made enormous advances yet the need for medical facilities is constantly growing: “What boots it at one gate to make defence, and at another to let in the foe?” We have overcome bacterial pollution of water, and now we watch chemical air pollution attack us; we control bacterial invasion of food, and suffer from the allergic and other toxic effects of new synthetic products; labor-saving devices open the way for boredom and the troubles of inactivity; vitamin deficiency gives way to hypervitaminosis. The misuse of antibiotics and tranquilizers produces its catalogue of fresh forms of ill health, and the term “iatro-genic”—referring to phenomena caused by medical treatment—ceases to be an obscure and rarely needed neologism when applied to illness.

In the light of these considerations, soberly presented, Dr. Dubos deplores the sheltered passivity, the dependence, and the expectation of effortless solutions for the problem of disease which characterize large sections of society. The public confidently waits for all microbial disease to be eradicated, but this is a will-of-the-wisp. Prevention and control should be our chief concern, not treatment and complete extinction of infectious disease. Control may, however, come into sharp conflict with other social forces: In a society in which economic considerations are predominant, removal of the causes of cancer and other diseases may encounter obstacles and call for much effort. However convincing, for example, the evidence that cigarette smoking greatly increases the risk of cancer of the lung, the advertisements inviting us to smoke cigarettes will not disappear from the television screens unless there is much more determined action than at present. Psychological and social forces must be taken fully into account. It is also demonstrated more fully now than in the past that for effective removal of the causes of disease, doctors cannot alone make or advise the necessary changes; they must collaborate with others—engineers, anthropologists, sociologists, administrators—to produce effects salutary for the community at large. In epidemiological research this is already well understood, but in the application of knowledge gleaned by such research, adequate team work has in many places lagged behind, and the combination of doctor and administrator has been thought sufficient.

“PERSONALIZED” MEDICAL care directed at the sick individual is, Dr. Dubos believes, inevitably required in Western countries because of their social mores and medical ethics, but in the emergent countries collective control through preventive methods is feasible as the main medical effort, and patently desirable. The five phases through which such a program might be realized are persuasively outlined: room is found even for the “native healer,” as has been seen in various African and Asiatic countries.

Dr. Dubos is not trained in medicine. He has come to his theme by observing, as a microbiologist, “how the prevalence and severity of microbial diseases are conditioned more by the ways of life of the persons afflicted than by the virulence and other properties of the etiological agents.” He deals with the manifold problems of “man adapting” from a standpoint different in many ways—none of them fundamental—from that of the medical exponents and practitioners of social medicine. His book has freshness, a zest, and force of conviction which carry the reader on, while the accumulated instances from biology and kindred fields indicate that these are not the high but windy aspirations of a naive sciolist; they rest on much knowledge, reading, and shrewd reflection. Here and there his assertions invite qualified dissent, but not in matters of substance, though his insistence that the methods of study appropriate to the whole man are essentially different from “the stock in trade of orthodox natural sciences” would surely bring him into sharp conflict with Karl Popper.

This Issue

December 1, 1966