The Life Science: Current Ideas of Biology
It is a curious anomaly of history that men made a careful study of the nonliving world before they seriously examined themselves. For three centuries, the study of physics has been regarded as the very prototype of exact inquiry. Even today it holds pride of place and gets the lion’s share of the money that governments devote to research. Out of the physical sciences grew the technology of the industrial revolution, giving us the many good and bad tools that dominate our life today. Biology, by comparison, has been considered as a very weak form of science and is still looked down on by many physicists and chemists. Yet the discoveries of biology and medical science have produced, in less than fifty years, changes far greater than those of the industrial revolution. They have added immensely to the health and happiness of mankind and have given us not only the problems of explosive population increase but also the knowledge that can allow the multitudes to be fed.
Understanding these changes involves technical knowledge of a different sort from that of the physical sciences. Biologists cannot use abstract symbolism and mathematics in the way that physicists do for the very reason that most living processes are influenced by many forces and by their long past history. This is why biology seems to mathematicians and other clever people to be an “inexact” science. But actually it involves knowing more, not less. A good biologist has to be able to think about his material from many points of view. In explaining his work to other people, he has to lead them also to see that living processes do not have single “causes,” but depend upon many factors and a long, long history.
Peter Medawar is a scientist who has this biologist’s vision and can impart it to others. Readers of The New York Review have good reason to know how well he writes. He and his wife have now produced a most attractive review of many aspects of modern biology. I must declare an interest, as the former tutor of both of them. I am entitled to be proud of them and to praise and to criticize. It is indeed gratifying that they have done so well. Peter has made immense contributions to immunology and made possible the practice of graft transplantation, for which he received the Nobel Prize. Although trained as a zoologist with no knowledge of medicine, he was the successful head of the most prestigious laboratory of the Medical Research Council, until partly paralyzed by a stroke. Jean, besides helping his amazing rehabilitation, has been the active director of an organization concerned with birth control and child welfare.
Between them, they have now produced a remarkable survey of modern biology and its social implications. They claim that it is about ideas, with a minimum of facts, but actually there is a lot of information, conveyed in an extremely concise, acceptable way. Short sentences and chapters, each of a few pages, only 173 in all, with aphorisms you will remember on almost every page. This is human science the way it should be presented. Firm in their convictions, they are yet ready to express doubts. We are not encouraged, however, to think very differently from the Medawars: the truth is told with humor but also with an asperity that is sometimes a little daunting.
They give us views of many aspects of life, literally from the cradle to the grave. Being both zoologists, they believe that an understanding of life must be firmly based in the study of animals. They give an excellent account of the essentials of evolutionary theory and of nature’s way of perfecting by selection, rather than by Lamarckian methods of instruction. The course of study that they followed in Oxford included a detailed survey of the whole animal kingdom, from an evolutionary point of view. Such comparative anatomy is now considered old-fashioned by those who know no better. But as the Medawars say, even molecular biology is grounded in the study of form.
It is true that they poke fun at some aspects of the study of comparative physiology, “piffling, physiological experiments” on the details of animal functioning. It seems to me that this scorn does not go well with the Medawars’ insistence on the value of all life. Those of us who study the details of the ways of life of insects and octopuses find them as beautiful as the details of antibody formation and perhaps in the end equally valuable for mankind too. The Medawars are indeed great putters down of what they consider to be pretensions. In commenting on the “hubris” of the molecular biologists, they manage at the same time to run down the old-fashioned critics of the subject.
Part of the challenge of their attitude is that it invites riposte and criticism, while still building a firm basis for agreement. Fundamental to their attitude is a belief in the virtues of analysis and they are not frightened by timid worries about reductionism. Yet they are also not afraid to proclaim that living things operate with a purpose, or to speak freely of teleology, a word they prefer to the genteelism “teleonomy” of Pittendrigh and Monod. They are even ready tentatively to admit to a belief in evolutionary progress.
Nonprofessionals will be specially interested when the Medawars extend themselves into the fields of social biology, which is their joint interest. Not surprisingly, they make scathing remarks about the possibility of positive programs of eugenics. Artificial selection over many generations would require a long dynasty of tyrants and “though the tyranny is not inconceivable, consistency of policy assuredly is.” However, they would be ready to advocate measures to prevent the propagation of painful and distressing conditions, such as hemophilia. They face up squarely to the question whether medical and other care may lead to the conservation and spread of unfavorable genes. The conclusion is that the risk should be accepted rather than leaving distressing diseases untreated. But as they point out, it is preferable to eliminate the disease, as is being done with malaria. As for the current controversies about intelligence, the only reference to them in this book notes that some of the evidence “has come under suspicion of having been fiddled.” Peter Medawar has since discussed the question of IQ at length in this journal (NYR, February 3, 1977).
Of course the Medawars are concerned over problems of increased population, but they do not tell us much about their attitude to differential increases between classes or nations. Perhaps they would hold that here strictly biological facts can give little help. They tell us that animal numbers in the wild are regulated by “force majeure—starvation and death by predation or infectious disease.” Curiously, they give no reference to the view of Wynne Edwards that many animal species have built-in methods of regulating their populations. Social customs seem often to drive the losers in ritual conflict to accept exclusion from breeding and even from feeding. Admittedly, there is controversy about the mechanisms by which such altruistic actions evolve. But we humans badly need to limit our populations by social conventions rather than “force majeure.”
Like other biologists, the Medawars are not very anxious to make forecasts about man’s future. They ridicule idiotic enterprises such as keeping human life in deep freeze or raising babies in bottles. But fertilizing embryos outside the body and re-implanting them is not too difficult and as applied to man it would be, as they comment, “in many ways a great improvement on ordinary adoption.” A more remote possibility is “cloning,” the production of an indefinite number of replicas of one egg. “But who is to be judged worthy of indefinite replication? The more one thinks of the enterprise, the less likely does it seem that it will ever come to pass.” They hint that such suggestions of biological engineering should not frighten the timorous because they are only based on “the deep-seated desire of many academics pour épater le bourgeois” and that the hunger for notoriety is greater than the hunger for truth. I think this is unfair and their hunger for aphorism takes them too far. Some of these techniques are possible and are already practiced by farmers. They need careful discussion.
Everyone knows now that grafts of tissue from one person to another will be rejected as foreign invaders unless the immune reaction can somehow be prevented. But the developments that Peter Medawar started in immunology have had much wider repercussions than this. The body has the most astonishing capacity to produce antibodies against almost anything, including for instance synthetic organic chemicals that have not yet been invented. The mechanism for recognizing each foreign body cannot therefore have been evolved by natural selection in the past, but it may depend upon a sort of natural selection going on within the body. According to the theory of Nils Jerne, the lymphocytes, which are the cells that produce the antibodies, are formed in a special organ dedicated to producing a variety of random mutations. This Generator of Diversity (GOD to the profane) continually provides new varieties of lymphocytes out of which some can be selected for multiplication if needed to make antibodies to a new antigen, such as a substance that the chemists have thought up.
This is only one of many ideas that the new science of immunology has produced. The whole question of how cells recognize each other is fundamental to understanding the individuality of each of us. A large class of auto-immune diseases may depend upon failure of the body to recognize some of its own cells and so to react against them. Cells may become antigenic as a result of a virus infection and perhaps this is the cause of multiple sclerosis and rheumatoid arthritis. One of the most fascinating developments is the evidence that the body develops immunity against tumors formed from its own tissues. This provides hopeful clues in the attack on cancer. It may be that regression of tumors, far from being rare, is occurring in the body all the time, as they are “spied out by circulating lymphocytes” and destroyed. Serious and malignant tumors may thus be due to a failure of the immune reaction. This raises all sorts of possibilities, including the idea that it may be worthwhile taking away part of a tumor, even if you cannot get the whole, “to remove the burden thrown upon the subject’s immunological defences.”
This may give some hint of the richness of ideas and facts which are current in cell biology today and which this book presents with unrivaled authority. The authors also give us a few chapters on other tissues, though they keep harking back to immunology. Half the chapter on circulation is about the lymphatic system and the thymus gland as a “finishing school for lymphocytes.” They are curiously puzzled over what use it is for the blood to clot, which seems pretty obvious to me when I cut myself shaving. Brains and nerves get very poor treatment, which is a pity, for much could be said of recent developments in these fields. They rightly note that those who study memory have “not yet thought of a plausible theory of structural encoding of neural memory, in the sense in which genetic ‘memory’ is structurally encoded in DNA.” With their interest in selective processes, they might have called attention to the evidence we have produced for the theory that learning occurs by selection among all the possible activities with which the individual is endowed. However, they do find time to emphasize, rightly, that Kant’s conceptions of space and time as forms of intuition are more in agreement with modern sensory physiology than are those of Bishop Berkeley.
Coming on at the end to the subject of senescence they are on more familiar ground again, and their investigation of why we grow old is a detective story in which we all have an interest. They don’t claim to have enough evidence to convict the criminal, but he is hiding somewhere among that gang of selective processes. This time it is a failure of selection to eliminate those genes that manifest themselves late in life. To give an absurd example, killing everyone whose hair turned gray would not eliminate the tendency, because the genes that make it possible have already been passed on. Senescence may thus be due to accumulation of late-acting bad genes. This they call the “genetic dustbin” theory of senescence. “It almost certainly represents part of the truth, but equally certainly is not the whole truth.”
What makes this book refreshing is the continual sense of contact between the writers and those they are addressing. They tell you things because they feel you will be interested. They want to help and they believe that science can help. Peter Medawar does not like to be called an optimist, because no sensible person should expect that things will be “best.” But they can be better, and he would like to be known as a meliorist—he wants things to be improved. The book ends with an expression of this faith:
In spite of its frightening groans and rattles, the great world machine can still be made to work, but not unless it comes to be accepted that the long-term welfare of human beings cannot be secured by policies that promote the interests of some people at the expense of others or even the interests of mankind at the expense of other living things. The unity of nature is not a slogan but a principle to the truth of which all natural processes bear witness. The lesson has been learnt too late to save some living creatures, but there may just be time to save the rest of us.