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428 THE LIFE SCIENCES tinents to immigration, the industrial revolution, the introduction of contra- ceptive devices, improvements in medical knowledge, and introduction of public health measures. Man, a highly social being, is an animal as well. In form and function, development and growth, reproduction, aging, and death, he is a biological entity who shares the attributes of physical life with the millions of plant and animal species to which he is related. This relationship, known since prescientific times, became part of established science long before the theory of evolution was proposed. It is the reason why studies of fungi and mice, flies and rabbits, weeds, cats, and many other types of organisms have contributed to understanding man and to improving his health and biological well-being, and why future studies with experimental organisms will bear on man's own future. Man's mental attributes form a superstructure that does not exist inde- penderlt of his organismal construction. Human thought is based on the human brain; the brain-and, hence, the mind, the "self" of each person is one of the derived, developed expressions of the genes that he inherited from his parents. Man's capacities are, thus, inextricably linked to his genes, whose molecular nature is now understood to a very high degree, but which presently lie outside his control. The social creations of man language, knowledge, culture, philosophy, society have an existence of their own and are transmitted by social inheritance from generation to generation. But they depend for both their persistence and change on the genetic endowments of the biological human beings who are subjected to them and, at the same time, make them possible. In these considerations, "man" should be taken as inclusive of all human beings on our planet. The brotherhood of all men is not only an ethical imperative; it is based on our common descent and on the magnitude of the shared genetic heritage. Man has organized "nations" geographic, political, economic, military, and cultural units that insist on their sovereign status. The short-range future of man will differ among these sovereign groups, particularly between the "developed" and the "under- developed" nations. This discussion is particularly concerned with prospects in the developed countries. THE GREAT HAZARDS War The considerations of the future of man that follow presuppose that man- kind will not be subjected to a nuclear holocaust. If such an event were to
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BIOLOGY AND THE FUTURE OF MAN occur, the problems of retaining or re-establishing social organization, the breakdown of health services, including the production and distribution of life-saving drugs, and the ensuing threat of worldwide epidemics would take precedence over all other aspects of human affairs. Modern technology is sufficiently powerful to make complete extermination of man a possibility. To accomplish such a deed would require overwhelming use of nuclear weapons over large areas of the globe and a deliberate effort to distribute lethal levels of fallout over all inhabited regions. Barring such extreme measures, some of mankind would probably survive a nuclear war. The acute dose of irradiation required to kill human beings in a single, brief exposure is relatively small. Accordingly, direct radiation from nuclear explosives would take an immense toll, but the survivors would probably be able to repopulate the earth. Those who survived the immediate impact of nuclear explosions would be subjected to chronic irradiation from fallout, which would lead to a variety of deleterious effects. In addition to the damage to their own bodies, the survivors would produce egg or sperm cells that would contain many new mutations leading to abnormal offspring. Nevertheless, the radiation dose that the survivors would have received from the initial exposure and subsequent fallout might often be low enough to permit them also to produce normal-appearing and normal-functioning children, provided the survivors would still want to create a new generation. Ironically, it is precisely under these circumstances that social inhibitions against control of human genetics would dissolve most rapidly; post-nuclear-war man would almost certainly utilize available genetic understanding and biological technology to guide the evolution of his species. Should Homo sapiens, as such, survive nuclear war, there can be no guarantee that he could reconstruct his civilization. Our technologically developed society rests on a complex web of production that could be rebuilt only with extraordinary difficulty. Meanwhile, this would probably occur in a world significantly altered. The ecological consequences of worldwide fallout and long-term rise in radioactivity are virtually impossible to predict. But plant and animal species vary remarkably in their radiosensitivity, and surely current food chains would be disrupted with such profound ecological consequences that it is not clear that man could continue to find sustenance, warmth, and shelter. Similar considerations may well apply to the possibility of widespread use of biological warfare. The constructive understanding of life that biology provides can also be used for wholesale destruction of life. Once undertaken, war, in the future as in the past, is liable to grow beyond control, whether it be conducted with physical, chemical, or biological
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430 THE LIFE SCIENCES means. A future for man can be assured only when the ultimate danger of modern war is fully recognized and mankind abandons warfare. Man and His Environment For thousands of years, since first he became a farmer, man has changed his general environment. Some such actions were favorable; for example, during a previous era the rainfall in the American plains was limited, enabling the Indians annually to burn the prairies to drive the buffalo. The resulting debris created our great grasslands and helped generate the deepest, grandest soils on this continent. But, deforestation and primitive methods of agriculture have denuded vast areas and exposed their soil to erosion. It was just such practice that silted the Tigris and Euphrates rivers, thus contributing to the demise of the great Sumerian civilization. With con- tinuing loss, precious soil is essentially irretrievable. Return of the dust bowl of the south central United States to productive agriculture will require years of expensive and intensive effort, which will be economically rational only when national requirements are desperate. Hundreds of thousands of acres of forest were despoiled without provision for reforestation. Large areas of South American forest have been cleared for agriculture, despite the fact that, within a year or two, the rich forest is replaced by a concrete- like laterite soil; until research provides the technology to prevent this, such forest should remain in the native state. But when such knowledge is in hand, vast areas could be opened for productive agriculture. Excessive hunting of some animals for food, and of the large predatory animals either for sport or in self-defense, has wiped out many species either wholly or in many regions. Witness the slaughter of the giant, Hightless Moa by the Maori after they found New Zealand (about A.D. 1200) and the decreasing numbers of virtually all the great birds of our own country. When Euro- peans first came to this country, it harbored 5 billion passenger pigeons and 50 million bison. The former are gone and only 6,000 of the latter remain. Less than 3 percent of the original acreage of redwoods now stands, and there is no record of the disappearance of great numbers of species from our prairies, lakes, and forests. And mankind is the poorer. The prospect of a planet populated exclusively by man and the few animal species he has domesticated is bleak indeed. How grim to think of a world without tigers, whales, condors, or redwoods! The rise in population density, the operations of modern industry, and the diverse products of modern technology have led to pollution of air, water, and soil by a wide variety of chemical compounds and even unde- sirable proliferation of certain living forms, notably algae, while defiling the
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BIOLOGY AND THE FUTURE OF MAN landscape and minimizing the exposure of urbanites and suburbanites to natural surroundings. Large-scale use of pesticides can start a chain in which these substances concentrate in plant and animal tissues and, when ingested, accumulate in the adipose tissue of the human body. As an illustration of this process, consider the record of Clear Lake, California, where DDD (a breakdown product of DDI) entered the lake at 0.02 part per million (ppm). A year later, its concentration was 10 ppm in the plankton, 900 ppm in fish that eat the plankton, and 2,700 ppm in fish that eat fish that eat plankton. No data are available concerning people who ate such fish. Similarly, the routine addition of antibiotics to feed of domestic animals leads to their ingestion by man. Exposure to repeated low levels of these drugs may inhibit growth of sensitive organisms and may thereby foster growth of resistant strains and so may decrease the effective- ness of these drugs to fight infection. The effects of these changes in the environment on man himself are not known. Although it is possible that some of the agents to which man is now inadvertently exposed will cause serious disease, shortening of the life-span, decreased fertility, or deleterious mutational changes in genes, none of these has as yet actually been demonstrated to have occurred. This, however, does not imply that dangers do not exist. Such possible effects may be numerous, yet difficult to discover. It has taken decades to establish the statistical relation between cigarette smoking and lung cancer; the same may also hold true for the relation between new factors in our environment and other diseases. Unlike the effects of acute, heavy doses of deleterious substances that rapidly lead to severe illness, pollutants are taken up in small amounts over long periods. Their effects, therefore, may be delayed for years or decades. Moreover, different individuals probably react differently to the same low level of exposure to a foreign substance. Some may excrete more of a given compound than others, thereby avoiding accumulation. Some may decompose the agent in their tissues, while others leave it unchanged. Some may be more resistant to its effects. If, as an arbitrary figure, one in 1,000 individuals will suffer ill effects from a specific agent, causal relationships can be revealed only by very large-scale studies of whole popu- lation groups. Yet if one incident in 1,000 seems a small effect, consider that, in a population of 200 million, as many as 200 thousand individuals would experience damage. Conceivably, the incidence of heart attacks may have been increased to this extent by the carbon monoxide of auto- mobile exhausts in regions where smog formation is heavy, but this has yet to be demonstrated. Appropriate studies would have to make use of large cohorts of people followed in their pattern of diseases, fertility, and life-span over very long periods perhaps longer than the professional
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THE LIFE SCIENCES life-span of a single generation of investigators. There is precedent for such studies in the research on the relation of smoking to lung cancer, but the scale of such studies must be greatly expanded. Until reliable evidence thus obtained becomes available, public health measures designed to minimize exposure to such pollutants are patently advisable. But surely a rule of reason should prevail. To only a few chemicals does man owe as great a debt as to DDT. It has contributed to the great increase in agricultural productivity, while sparing countless humanity from a host of diseases, most notably, perhaps, scrub typhus and malaria. Indeed, it is estimated that, in little more than two decades, DDT has prevented 500 million deaths due to malaria that would otherwise have been inevitable. Abandonment of this valuable insecticide should be under- taken only at such time and in such places as it is evident that the prospective gain to humanity exceeds the consequent losses. At this writing, all avail- able substitutes for DDT are both more expensive per crop-year and de- cidedly more hazardous to those who manufacture and utilize them in crop treatment or for other, more general purposes. The health problems engendered by undesirable contaminants of the environment may also be raised by substances that are intentionally in- gested. Only large-scale, long-term epidemiological research will reveal whether the contraceptive pills, pain killers, sleeping pills, sweeteners, and tranquilizers, now consumed on so great a scale, have any untoward long- range effects on their consumers.* Man has always been exposed to the hazards of his environment and it may well be that he has never been more safe than he is today in the developed nations. Food contamination is probably minimal as compared with that in any previous era, communal water supplies are cleaner, and, despite the smog problem, air is probably less polluted than in the era of soft coal or before central heating systems were the norm. Witness the fact that jungle-dwelling natives of South America exhibit a considerably greater incidence of chromosomal aberra- tions in their somatic cells than does the American population. But modern man also increasingly exposes himself to the chemical products of his own technologies and has both the biological understanding to ascertain the extent of such hazards and the prospect of technological innovation to minimize them where they are demonstrated. To do less would be im- provident and derelict. The federal record systems, particularly those of the Veterans Adminis- tration and the Department of Defense, are already available for epidemi- ological follow-up studies among veterans. They could be made still more useful by utilizing record linkages, i.e., linking together the many inde ~ This sentence was written in June 1969. Revelations of the untoward effects of both steroid contraceptives and cyclamates were made public months later.
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BIOLOGY AND THE FUTURE OF MAN pendent records of births, illnesses, deaths, and other vital statistics in the defense and social security agencies and many others. While this entails the possibility of intrusion into the privacy of individuals, it should be possible to erect safeguards against misuse. Such safeguards will be effec- tive if the prevailing climate of opinion welcomes the attainment of useful information and forbids authoritarian attempts at improper exploitation of linked data. Man's biological future depends on knowledge of his experi- ences, good and bad, and record linkage is an important means of acquir- ing such knowledge. Even more subtle than the effects on man of pollutants and of specific agents may be the effects of changes in his general pattern of living. Urban aggregation has removed many men from natural surroundings. The in- creased level of environmental noise, caused by industrial procedures and automobile and airplane engines, has added a new dimension to sensory exposure. Crowding together in overpopulated regions has greatly changed the interrelations among people who, only a few thousand years ago, lived in small bands with minor contact with one another. Development of the science of animal behavior is beginning to give some insight into the interrelations between genetically founded behavioral attri- butes, the effects of early training, and the effects of the immediate environ- ment on overt behavior. We are prone to think of hostility, crime, and other antisocial behavior as conditioned by social circumstances. And there is, indeed, ample evidence to support this belief. We do not know, however, how much personal unhappiness and social distress is a consequence of man's basic biological nature in conflict with an unnatural, essentially non- human environment. The stereotyped movements of caged polar bears, viz., the reaction of bears to a non-bearlike environment, may well have analogies in mentally ill patients. Undesirable modes of behavior as well as various psychosomatic illnesses may frequently be extreme expressions of maladjustments of the human animal. Hopefully, research in behavioral biology will furnish deeper insights into man's nature, and application of these insights may lead in the not-too-distant future to fundamentally new parameters for environmental engineering. These will endeavor to fit the environment to man instead of leaving man unfit for the environments he created. Important to such studies are the nonhuman primates apes and monkeys; every effort should be made to assure the survival of as many such species as possible. Scientific advancement has enabled man to triumph over his environ- ment. With technological skills and machinery he is able to move, change, and control natural resources for his agriculture, forestry, fisheries, recrea- tion, and urban and industrial development. The wasteful, injurious prac- tices of yesterday have largely been abandoned. Forests are replanted as
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THE LIFE SCIENCES they are timbered; soils are fertilized so as to compensate for the minerals removed by the plant harvest; saline soils are restored to useful tillage by large-scale leaching; a beginning has been made at reversal of thoughtless practices that could result in the almost irreversible death of large lakes. Although Lake Erie is in serious trouble, Lake Washington is being recov- ered, and Lake Tahoe may yet be saved. Civilization depends and will continue to depend upon the renewable resources of the environment- land, water, air, and populations of plants and animals, both wild and cultivated. Fortunately, the public and its representatives are increasingly anxious about the status of these resources and the vital role they play in our survival and general well-being. Environmental pollution becomes of increasing concern as the human population congregates in cities and occupies more of the landscape. The public is pressing for greater understanding of the function and interaction of the biological and physical elements of the environment and for appli cation of this understanding to the management of the renewable resources that supply man's food, clothing, recreation, and shelter. This sense of urgency, arising originally from the desire simply to assure the viability of life an char Planet is heightened by growing public appreciation of the ^~ ^~ i- 7 ~ I- 1 importance of beauty, natural and manmade, ~n our surroundings for the improvement of the quality of life. Many reports have directed attention to the more obvious gross problems of managing the environment, problems that derive from a combination of population growth, advancing technology, and increased technological pro- ductivity. Concern has been expressed with respect to rising atmospheric CO,; increasing particulate content of the atmosphere; buildup of radio- activity; accumulation of diverse chemicals in lakes, streams, rivers, coastal waters, and the ocean itself; soil erosion and destruction; replacement of fertile, green farm and woodland by highways and towns; rising noise levels; and "thermal pollution." Figure 49 displays the record and projec- tion of various endeavors of our society, each of which must necessarily adversely affect the environment. If these projections are even approxi- mately correct, and if each of these enterprises grows without appropriate monitoring for its ecological consequences' the totality could constitute the saddest, most brutal, and most disastrous act of vandalism in historic. Economic growth, insofar as it leads to higher standards of living, better health, and national security, is clearly to be desired and fostered. But life should be worth living, and this generation should assure that it can transmit to posterity a land whose beauty and resources have been safeguarded, embellished, and protected. To do so demands a level of regional and national planning, with due regard for ecological understanding, without historic parallel. Moreover, we must assume the burden of transmitting
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BIOLOGY AND THE FUTURE OF MAN 435 Air Freight Air Transportation (Revenue Passenger 3150% \ Miles) 2615% A_ 8 1l 1250 , a) Q ° 1000 > a) C: ._ o ~ 750 ~5 0 CO Cal ._ - o c 500 o ._ x LL ~ 250 a) CL Public Construction / of Highways 2020% ~v I .............. . ~.. .. 1947 '50 '60 '70 '80 '90 2000 ................... Utility Sales of Electricity 1 3 50 % '~4 Chemicals and Products go Residential Construction .. Public Construction of <~4 Water and Sewerage .~ Automobiles ~4 (Annual Production) '~4 Nonferrous Metals and . ~ Products ,.1 Paper and Paper Board ., Production ..~4 Gross National Products .~4 Petroleum Consumption ·... ....... ....... ..... ...... d Steer Ingot Production and Detergents FIGURE 49 Projections of expansion of certain industries that have an influence on pollution. Medium-level projections, 1970-2000. (Data from H. H. Landsberg, L. L. Fischman, and J. L. Fisher, Resources in America's Future, published by The Johns Hopkins University Press for Resources for the Future, Inc., Washington, D.C., 1963.) such understanding and planning capability to the developing nations, most of which still retain the native qualities of their environments and are in danger of galloping destruction of their resources as they race to develop their technological capabilities and to achieve economic independence and a reasonable standard of living. Biologists and engineers should work jointly to design cities of quality and beauty. Dwellings and industrial structures should be surrounded by at least minimal lawns and plantings of ornamental trees, shrubs, and
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436 THE LIFE SCIENCES flowers. There can be no relaxation of efforts to assure "clean" air and water, although useful operational criteria for these remain to be established. The burden of responsibility must be made to lie with those whose activities introduce contaminants into the environment. Even now, there are tech- nological means for dealing with most pollutants at the source. A rational society will insist that these means be utilized and that new, cheap, and efficient means be continually sought. Where none exist, it becomes essential that the advantages afforded by polluting activities nondegradable detergents and pesticides, heavy use of fertilizer, the exhaust of internal- combustion engines, the sonic boom, and the contrails of a supersonic transport be weighed against their cumulative effects on mankind. It is doubtful that, at this writing, the evidence on which to rest such judgments exists. Patently, this evidence must be sought. Through care, planning, and utilization of the sciences of agriculture and forestry, the landscape of the country can be conserved, returning it to its simple charm, with neither billboards nor automobile graveyards. More- over, a great and complex effort based on ecological understanding will be required to cope with the pressures that annually result in conversion of one million acres of farm and wildland to highways and building sites. Certain areas representative of nature seashore, mountains, desert, forest should be preserved forever wild for recreation and on a scale adequate to preserve the natural biota. Ecologists and environmental biologists, together with other scientists, should combine to develop a strategy for the wise use of our renewable resources and the preservation of an attractive environment. The attainment of these goals does not depend alone on the technical skills of biologists and other scientists and engineers; people generally must desire to live in harmonious, healthful environments. Without broad social motivation supporting their use, the knowledge and the skills of the specialists will lie fallow. The Size of Human Populations In the seventh century, according to the records of the Church of Mayo, two kings of Erin summoned the principal clergy and laity to a council at Temora, in conse- quence of a general dearth, the land not being sufficient to support the increasing population. The chiefs . . . decreed that a fast should be observed both by clergy and laity so that they might with one accord solicit God to prayer to remote by some species of pestilence the burthensome multitudes of tile inferior people.... St. Gerald and his associates suggested that it would be more conformable to the Divine Nature and not more difficult to multiply the fruits of the earth than to destroy its inhabitants. An amendment was accordingly moved "to supplicate the Almighty not to reduce the number of men till it answered the quantity of corn usually produced, but to increase the produce of the land so that it might satisfy the wants of the people." However, the nobles and clergy, headed by St. Fechin, bore down the opposition and
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BIOLOGY AND THE FUTURE OF MAN called for a pestilence on the lower orders of the people. According to the records a pestilence was given, which included in its ravages the authors of the petition, the two kings who had summoned the convention, with St. Fechin, the King of Ulster and Munster and a third of the nobles concerned.... W. J. Simpson, A Treatise on Plague The upsurge in the growth of human populations constitutes the major problem for the immediate future of man. Accordingly, it is difficult to exaggerate the urgency of deepening our biological knowledge of man and his environment. There is every reason to expect that, by the end of the century, a brief 30 years from now, the world will have twice its present population. Unless forestalled by a worldwide holocaust, in the year 2000 the world population will surely be not fewer than 6 billion people, and may well exceed 7 billion. (See Figure 50.) Since the means for improved control of disease are already at hand, if the food supply keeps pace, a World Population (billions) -~7.5 . ........................ . - 0 200 400 600 800 ~1144 ~8~ 1000 12001400 1600 1800 2000 1900 Date -. ~ I............. I............ ......... I............. ~ ~ l l 4 15 30 2 \ 100 )8 ) from the beginning FIGURE 50 World population growth (projected with assumption of constant fertility levels and declining mortality). (Small numbers outside parentheses indicate the rapidly decreasing number of years required to increase world population by a billion people.) (From World Population: A Challenge to the United Nations and Its System of Agencies, UNA-USA National Policy Panel on World Population, May 1969.)
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United States . _ -Canada, Australia - Latin America rEurope anon | Africa USSR 1968 1930 THE LIFE SCIENCES world population of 7 billion will be reached even if present birth rates are considerably reduced. Population growth is occurring most rapidly in the newly developing nations, where abject poverty is widespread, the mass of the population is uneducated, and the industrial sectors of their econ- omies are poorly developed. (See Figure 51.) Moreover, future demands on the biosphere are not to be measured by simple extrapolation from the present. Much of the present population is badly nourished, while, because of improved communications and appre- ciation of the living standards of developed nations, popular aspirations for improved living conditions are high in almost all nations. Even a doubling of per capita consumption of protein, clothing, and shelter would leave present aspirations unfulfilled. If the projected doubling of the world's population is realized, and if political order is to be maintained, it is not unreasonable to expect that the demands on the biosphere by the end of the century will be three or four times those-of the present! The problem of achieving such increases becomes staggering when we realize that the end of the century is so close that this year's infants will then be in the middle of their childbearing period. Moreover, regard for the human heritage requires that these needs be met without despoiling either the quality of man or the material base from which he draws life. Distribution of Population India China Japan Rest of Asia 7.5 billion 1830 / -3.4 billion [I...' ,... ~ ~ :# ~ ::::::::O |-.' '! ~ .' ~ .. ,. #, . . // / 2.0 billion ' ~ / 1968 2000 /U.S. 200 350 / Canada, Australasia 40 70 / Latin America 270 760 a.,_ A=^ 57Q 860 U.S.S.R. 240 400 India 520 1330 China 730 1480 Japan 100 140 Rest of Asia 590 1550 Europe 460 Africa 330 1.0 billion FIGURE 51 Projected population of developed and underdeveloped nations in the year 2000. (From World Population: A Challenge to the United Nations and Its System of A agencies, UNA-USA National Policy Panel on World Population, May 1969.)
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BIOLOGY AND THE FUTURE OF MAN be applied to the immediate problems of agricultural production is not due to biological limitations of genetic endowments in different human Livery region Is poten- tially able to produce the numerous trained persons needed to explore and solve the specific problems of the region. Obviously, these problems are not restricted to agriculture. Each region requires a corps of local scientific and engineering specialists to make available to its population the bene- ficial results of industrial and scientific technology, and American technical assistance should give high priority to assisting in the endeavor to train such specialists. The immediate demands on the biosphere have been generated and exacerbated by rapid population growth, which, particularly in the devel- oping nations, is the consequence of the almost abrupt inauguration of public health and sanitation measures, producing drastic reduction of the death rate while the birth rate remained unchecked. Because no imaginable program of population control could restrain population growth signifi- cantly in the next decade, the emergency problem is to attain, as rapidly as possible, adequate levels of education and significant local programs in agriculture and related science and technology for the vast numbers of the human race. We are not optimistic that this can be achieved in time to avert disaster in the 1970's, but the attempt must be made. It is all too evident that the surplus agricultural productivity of a few developed nations Canada, Australia, the United States" even if used to the full, can have little impact in this worsening situation. Moreover, population growth in these nations will, in time, require domestic utilization of their own pro- duction. If this estimate of the situation is correct, the acute problem is not that of population size itself but of the speed of modernization and the extent to which the gains so realized are offset by the speed of population growth. The speed of modernization turns on many factors, on national and inter- national allocation of resources for space' war, schools, and factories, inter alla. But basically it also depends, even at quite local levels, on the extent to which the growth of agricultural production can be made to exceed that of population. Investment in development can be made only after the current costs of growth have been met. - groups, but to the limitations of their education. ~ POPULATION CONTROL: THE LONG-TERM PROBLEM The long-term prospects for a truly human civilization depend in very large measure on whether humanity can, in time, succeed in moderating its fecundity. Only if this effort is successful, and early, can our progeny be offered the opportunity to relish the gift of life and to maximize their own 441
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442 THE LIFE SCIENCES human potential. The dimensions of the problem are dramatically evident in the remarkable diminution in the time required for doubling of the world population, as seen in Table 69. This remarkably accelerated growth, largely the result of decreasing death rates due to simple public health and hygienic measures accompanied by commensurate increases in agricultural productivity, occurred first in Europe and the United States and is now operative also in many of the developing nations, with startling consequences. Witness Brazil with a population of 17.5 million in 1900, 52 million in l9SO, 71 million in 1960, 83 million in 1966, and an estimated 240 million by 2000, or a 14-fold increase within We twentieth century! Yet concern for population growth is not new. In Politics, Aristotle warned that ". . . neglect of an effective birth control policy is a never- failing source of poverty which, in turn, is the parent of revolution and crime," and he advocated that parents with too many children practice abortion. He went unheeded through the following centuries as the Romans encouraged large families to man their wide-flung armies, the Judaeo- Christian ethic considered children as gifts of God, and St. Augustine stated the purpose of Christian marriage to be procreation, a view unmodified by the Reformation. Much earlier, Tertullian noted that "the scourges of pestilence, famine, wars and earthquake have come to be regarded as a blessing to crowded nations since they served to prune away the luxuriant growth of the human race." From time to time, advocates of population control appeared, most particularly Malthus, who stated that, otherwise, TABLE 69 Time Required to Double World Population TIME WORLD POPULATION YEAR REQUIRED (YEARS) 250~000~000 500,000,000 1,000,000,000 2,000,000~000 4,000,000,000 8,000,000,000 1650 1 850 1930 1 97Sa 2005 a 1,649 200 80 4Sa 30a 0 Estimate.
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BIOLOGY AND THE FUTURE OF MAN population would always rise to the limits of food-production capacity, so that necessarily there would always be hunger and poverty. (Ironically, Malthus rested his case on the history of eighteenth-century United States.) Unfortunately, his teaching was rejected both by the Christian ethic and by Marxism, which taught that overpopulation is merely a capitalist notion invented to justify the poverty of working-class peoples and is rectifiable by enhanced production and improved distribution rather than by birth control. Malthusian predictions have largely been justified, although he foresaw neither the consequences of the introduction of agricultural technology nor the demographic consequences of simple hygienic measures. Today, these problems must be considered separately in global and local contexts. The food crisis of some developing nations, considered earlier, is patently urgent. Yet, worldwide, since about 1950 agricultural productivity has grown by about 3 percent annually, while population increase has averaged less than 2 percent. Indeed, it is estimated that if worldwide per capita food con- sumption had held constant at 1955 levels, despite the population increase by 1975 there would have been a world surplus of 40 million tons of wheat and 75 million tons of rice. This will not occur because of both rising per capita food consumption and the controlled productivity practiced, in vary- ing degree and kind, in the United States, Australia, New Zealand, Canada, France, and the Argentine. Meanwhile, the developing nations, caught up in the worldwide revolution of rising expectations, find themselves short of food and of capital for development. Income for development can be generated by increased production and by decreased reproduction. Clearly, both are needed. Some inherently undesirable means to decrease the rate of population growth, e.g., war, famine, pestilence, are all too evident. On the other hand, populations that have learned to reduce their fertility to the point where they enjoy good health and the longevity characteristic of the more developed nations, and whose growth amounts to only 1 percent per year should encounter no substantial difficulty in reaching a stationary position if that is clearly desirable. Only as that occurs can increased production of agriculture and the extractive and manufacturing industries be utilized for development and increase in the general standard of living. It may well be asked how many countries can be expected to do this soon enough. Markedly in- creased agricultural productivity accompanied by population growth inevitably leads to rapid urbanization, frequently at a rate in excess of any prospect of gainful employment of the translocated individuals. Yet this process, at a moderate rate, is imperative if a developing agrarian society is to acquire a sufficient urban population to sustain its growing industry, educational system, etc. 443
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444 THE LIFE SCIENCES As we have indicated, if the oncoming food-shortage crisis can be averted, known technology, if put into practice, can readily so enhance food produc- tion as to defer the world food problem almost indefinitely. It is the combi- nation of new strains and application of fertilizer that has so remarkably increased agricultural yields in Europe, Japan, and the United States. In a general way, application of a ton of fertilizer nitrogen yields an increment in crop production equal to the basic yield of a 14-acre plot. Stated differently, there are about 3.5 billion acres of land presently under culti- vation; application of $10 worth of fertilizer per acre would increase pro- duction by about 50 percent, i.e., for $35 billion per year or $10 per capita, worldwide, world food production would rise by the equivalent of 1.7 billion acres of average land and a 50 percent increase in available food, per capita. Moreover, it has been calculated that if all land now in tillage were cultivated as in Holland the world could support 60 billion people on a typical Dutch diet; if it were managed as in Japan, it could support about 90 billion people on a typical Japanese diet. And all this is possible apart from the realizable expectation of yet another agricultural revolution based on improved control of agriculture, growth of food yeast, bacteria and algae, or synthetic foodstuffs based on petrochemicals. Approximately one acre is required to feed one man by efficient current agriculture, yet a one-square-yard tank growing algae can produce all his caloric, protein, and vitamin needs! All of which is to say that measures to upgrade agri- cultural practice in the developing nations could forestall a Malthusian crisis for more than a half century, even at current rates of population growth. But with what consequences? The problem of population growth involves much more than merely increasing agricultural production. The constraints to population size are all too visible even in the traditional self-sufficient agrarian society. Such societies have rarely been able to combine high population density with good health and relative freedom from poverty. But it is hard to specify the limits to the density of population that can be supported in health and prosperity by a highly educated population making sophisticated use of energy and raw materials and continuing to develop both its basic science and technology. There is reason to believe that, given the time and effort required to increase all forms of production sufficiently, this planet can sustain in relative abundance a total population considerably larger than the present one. Although no data are available to establish what the maximum might be, it is patently very much larger than at present. One can argue, however, that the maximum possible is decidedly greater than the optimum. Even the present population suffices to populate the planet, at all times, with the diversified human talent required to contribute to progress on all human
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BIOLOGY AND THE FUTURE OF MAN fronts- science, the arts, industry, government, eta. At some point, industry must forego population growth as the underlying basis for economic ex- pansion. Meanwhile, many of the most tragic ills of human existence find their origin in population growth. Hunger, pollution, crime, despoliation of the natural beauty of the planet, irreversible extermination of countless species of plants and animals, overlarge, dirty, overcrowded cities with their paradoxical loneliness, continual erosion of limited natural resources, and the seething unrest that creates the political instability that leads to international conflict and war, all derive from the unbridled growth of human populations. The fortunate nations are those that have, spontane- ously rather than as a matter of national policy, achieved a low rate of population growth or an exact equilibrium of the birth and death rates. Accordingly, another set of important emergency problems of a biological nature are those relevant to a reduction of human fertility. In the long run, birth rates must come down if death rates are to stay low, and in the short run, lower fertility would speed the process of modernization by widening the difference between the growth rates of population and pro- duction. Reductions of the birth rate in the underdeveloped countries have an additional advantage. High birth rates produce high proportions of young people. In virtually every country with a birth rate of 40 or more per 1,000 population, more than 40 percent of the total population is under age 15. Under these circumstances it becomes almost impossible for such a society to increase its working capital- to generate enough wealth for school construction, higher education, improved housing, or industrial plants. In consequence, for example, the illiteracy rate must surely rise, despite national determination to lower it. In advanced countries with low birth rates, between 25 and 30 percent of the total population is under age 15. A reduction in birth rates brings down rates of growth and reduces the proportion in the ages of childhood dependence. Correspondingly, it increases the proportion of the popula tion in the productive years of life. Indeed, very high birth rates speed population growth in two ways: ( 1 ) they swell the entering stream of life; and (2) by creating young popu- lations they cut the rate of depletion through death. Today, the lowest crude death rates (i.e., annual deaths per 1,000 population uncorrected for age) are not found in the most highly developed countries. The world's lowest crude death rates are found in such places as Taiwan, Singapore, Puerto Rico, and Chile, where health protection has become relatively good and a history of high birth rates has left a young population. In the long run, reductions in birth rates reduce growth both directly and indi- rectly by increasing the average age and, other things being equal, the crude death rate. Clearly, the possibilities of modernization would be
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446 THE LIFE SCIENCES greatly enhanced, globally, if rates of growth could be cut in 15 years from 3 percent to, say, 1 percent by reductions in birth rates. This would mean that populations now growing at rates that double in 23 years would come to a rate that would give them 69 years in which to absorb the increase, viz., the burden of natural increase in the newly developing countries would then be about that experienced by the United States in recent years. Most societies and individuals desire to limit. the size of families, but they are usually not content with a family size corresponding to zero growth of the population. Although, at the present stage of population growth, any reduction in family size is important, ultimately the mean family size will have to be limited to a replacement number. Family planning is not equivalent to population control. Family planning is the rational and deliberate spacing of children in the number desired by the parents. But that number is determined by cultural considerations, family income, and ego satisfaction in the developed nations and by the economic utility of children in the underdeveloped nations. Accordingly, large families are the norm among the affluent and among the ignorant poor. Population control demands that families be limited to the replacement rate. Nothing can do more to help obtain reductions of fertility than the development of more efficient, cheap, safe, reversible, and acceptable methods of contraception. People will use even the best of methods only when they want to have fewer children. Historically, whereas strongly motivated couples have even utilized inadequate methods of contraception and resorted to abortion, weakly motivated populations must be enticed to use even the best possible methods. Today, readiness to accept contracep- tion is widespread. More than half the population of the developing nations live under governments that have decided, as a matter of national policy, to foster the spread of family planning and limitation. The list includes most of the countries of Asia and a goodly number in Africa and Latin America. Most of these countries are developing educational programs to interest and inform their people and service programs to give them supplies. Careful surveys of attitudes toward reproduction have been made in more than 20 countries. Virtually everywhere, the majority of women desire to limit their childbearing. This does not mean that they want only two or three children, but that they want to stop before their families get truly large. Moreover, where services and supplies are made available, women are beginning to seek them in large numbers. Taiwan, South Korea, Hong Kong, and Singapore have clearly reduced their birth rates through their family planning programs. Today, in the developed nations, contraception has changed rapidly from use of the older conventional methods to the combination steroid pill. In underdeveloped countries, new contraceptors are mainly using the plastic
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- BIOLOGY AND THE FUTURE OF MAN intrauterine device. Neither method is perfect, but both are spectacularly effective and successful compared with the conventional contraceptives, "rhythm" methods, Eric. The availability of the cheap intrauterine device has encouraged governments of underdeveloped nations to build the organi- zations they require to spread family planning practices. With such organizations in being and operative, the next technological innovation can be introduced much more rapidly. It is because they have effective methods, hope for better ones, and the organizations to make use of them, that such countries as South Korea, Taiwan, India, and Pakistan now hope to halve their birth rates in 15 years. If they could do so, their long-run problems of modernization and economic development would be greatly simplified. The world needs better methods than are now available. The pill and the intrauterine device represent major innovations because, temporally, they separate contraception from coitus. The intrauterine device is prob- ably at a very early stage of development. An unacceptable proportion of all users spontaneously eject it, bleed, or suffer discomfort. On the other hand, apparently the majority of those who accept it wear it without aware- ness and with very high effectiveness. Two to three years after acceptance, 50 percent or more of women continue to wear their devices. It is likely that better procedures, better materials, and better shapes will lead to a greatly improved experience. Clearly, it is imperative that appropriate, vigorous investigation be undertaken to solve the riddle of the mode of action of these devices and to ameliorate their occasional side effects. Similarly, work is needed to reduce the side effects of steroid pills, to minimize their effects on lactation and on thromboembolic phenomena, to reduce their costs, and to establish systematically and in sustained fashion the actual experience of those who take them, to reduce the frequency of subsequent multiple births and, most importantly, to establish the biological consequences of long-term use with complete certainty. Similarly, an effort to find means of replacing the oral route of administration with a depot injection, vie., an injection allowing a steadier rate of absorption and, hence, smaller and longer-lasting doses, would be well repaid. Meanwhile, as this research proceeds, we deplore statements decrying use of steroid pills on the ground of their manifest occasional untoward side effects. Since the death rate from such usage is well below the death rate from pregnancy itself, these pills not only afford millions of families the opportunity for a richer, fuller life while checking the demographic explosion; on balance they also spare the lives of a significant number of women who would otherwise die of the complications of pregnancy. It would be highly desirable, of course, to have a method that is, in effect, permanent until positive measures are taken to counteract the con- traceptive. Children are often conceived as a consequence of careless con 447
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448 THE LIFE SCIENCES traceptive practice. Doubtless, birth rates would drop faster if there were a method in which carelessness meant failure to counteract a contraceptive. Clearly, however, such a development could pose serious problems of personal freedom unless the counteracting agent were freely available. Only a beginning has been made in relevant basic research. Among other things, we need to know a great deal more about tubal events, includ- ing gamete transport, fertilization, and zygote physiology. The fields of neuroendocrinology, immunological suppression of reproduction, blastocyst nidation, gonadotrophin chemistry, and the mechanisms of sex hormone action urgently need development. An intensive program of basic research might produce important results that could facilitate population control. The fundamental knowledge, the techniques, and the requisite base of pro- fessional skill for such an effort are now beginning to appear. In the long run, all practical results depend on basic research. But in the long run, unless birth rates are lowered rapidly, populations will become multiples of what they are today unless death rates rise. In the past decade, applied research based on many preceding years of basic research has made possible the contraceptive pills, the intrauterine devices and, conse- quently, the beginnings of a birth rate decline in some developing areas as well as in developed nations. Further basic research is greatly needed to prepare for yet further advances, and it is the only pathway to completely new approaches in population control. Meanwhile, intensification and enlargement of applied research is an urgent necessity. The United States and other developed nations find themselves in the embarrassing position of advocating that other nations increase their efforts at population control. Granted the validity of this position, viz., that it really does address itself to the self-interest of the affected nations, such a posture is not readily acceptable when the advice comes from a nation that has not itself adopted comparable internal policies. Since this country is in the fortunate position of enjoying a high economic level and a rela- tively low population growth rate, and while our total population is not yet excessive for our natural resources but is on the way to becoming so, the moment is opportune to examine our internal policies and alter these as seems appropriate. Clearly, our relatively low rate of population increase reflects the fact that American parents have not been behaving in the manner seemingly encouraged by the national mores and laws. Is it not appropriate to recon- sider laws that discourage abortion, forbid or make difficult distribution of birth control information and devices, and encourage large families by income tax forgiveness and by other social measures? These derive from an earlier ethos when an expanding population was required to develop the national frontiers. They seem entirely inappropriate today.
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BIOLOGY AND THE FUTURE OF MAN 449 Nor is the United States immune from the population explosion. Until recently our population growth has been dominated by the extremely low birth experience of the depression years and the subsequent war. But the children of the "baby boom" are just entering the child-bearing population. Thus, our female population in the age range 16-44 was 32 million in 1940~ 34 million in 1950, and 36 million in 1960, but it will be 43 million in 1970 and 54 million in 1980. The potential for an extraordinary burst in population is evident in the very fact of the existence of this breeding popu- lation. The current rate of population growth, i.e., the excess of births over deaths, is about 2 million per year, yet it is estimated that about 500,000 babies per year are "unwanted." Surely, provision to the mothers of these unwanted babies of information, contraceptive materials, or legal abortions would make for a happier society while reducing the societal burdens of population growth. Moreover, it should be understood that the penalties for population expansion are far greater in an affluent society than in a marginal economy. This is already painfully evident in the United States. Rising per capita real income places less and less tolerable burdens upon the environment: vastly increased solid waste, nondegradable detergents, pesticides, con- tainers and trash, more automobiles, heavier traffic, increased CO and CO' production, more smog, rapid erosion of fields for airports, highways, parking spaces and suburbia, rapidly increased water usage for anything . .... . . · . but drinking, Liz., a~rcondit~on~ng, swimming pools, metal-fabricat~on and paper-production plants, etc., while the same processes accelerate the de- pletion of all our nonrenewable resources-oil, iron, and copper ores, etc. Indeed, this is the lesson of Figure 49. Further, consider the seemingly impossible burden of coping with the demand for college education: college enrollments, which were 6 million in 1965, will be 8 million in 1970, 10 million in 1975, and 12 million in 1980. The effort required to meet all the expectations of this burgeoning population will be enormous and ... ... . _, wall utilize more and more ot our precious land and irreplaceable resources. This is in clear contrast to the burden upon the environment generated by adding to the population of a developing nation more individuals whose mean income is but a few hundred dollars a year. Clearly, the national interest and our individual interests would be well served by all measures that would damp the demographic explosion at home as well as abroad. There is, however, one aspect in which population control and the health of the population are at odds. Population control would be furthered by encouraging late marriage, a principal factor in the low birth rate in Ireland. But the incidence of such congenital defects as Down's syndrome and cleft palate, as well as of twinning, rises with the age of the parents. Hence, the optimal situation would be that in which marriage occurs at a
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450 TEIE LIFE SCIENCES young age and a family of two or three children follows shortly thereafter. Success in such a program then requires the full cooperation of society and 20 to 25 years of uninterrupted, successful contraception. Without sterili- zation, statistically, this seems an unlikely prospect unless research can provide much simpler and more effective contraceptive methods than those presently available. Guarding the Genetic Quality of Man The human gene pool is the primary resource of mankind, today and to- morrow. The present gene pool is the culmination of 3 billion years of evolution and natural selection. The physical vigor, long life, and intel- lectual capacity of most humans reflect the fact that, historically, natural selection has minimized the incidence of genes that, when expressed in the homozygous phenotype (an individual with two identical genes for the trait in question), would result in serious physical or mental incapacity. How- ever, advances in medicine in the last few decades have dramatically altered this situation. The "engineering" of human development so as to permit survival despite the handicap of such genetic endowment is called "euphenics" ("eu"- well, "phen" appearance). By ensuring survival and, thus, permitting the reproduction of such homozygotes, medical prac- tice has relaxed the selection against such genes. For example, formerly the intellectual deficit of most phenylketonuric children was such that they were unable to reproduce; when raised from birth on a suitable phenylalanine-poor diet they will now, presumably, marry and have offspring. Instead of "extinction" of the genes responsible for the disease in the nonreproductive homozygote, this should lead to an increase in the frequency of these genes in future generations and conse- quently an increase in phenylketonurics. A similar situation obtains for all other genetic afflictions that can now be neutralized by various treat- ments. Consider pyloric stenosis, an abnormal constriction at the junction of the stomach and intestine; this is a relatively common hereditary disease of the newborn, occurring in about 5 out of 1,000 live male births and in 1 out of 1,000 live female births. Formerly, most infants so afflicted died in very early life, but 50 years ago a surgical procedure was instituted that permits survival and normal health. The survival and later reproduction of children treated with that procedure has resulted in the perpetuation of this genotype; among their offspring the frequency of infants with pyloric stenosis is about 50 times higher than in the general population. And these children, having been operated upon, will again later produce a surplus of their own affected kind. Thus, a continuous increase of the disease must be expected in successive generations. Similar considerations apply to
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BIOLOGY AND THE FUTURE OF MAN 451 galactosemia and fulminating juvenile diabetes, and the list must grow as clinical medicine learns to circumvent the consequences of many other genetic disorders. The extent of this problem is evident from the fact that, even now, 6 percent of all infants have detectable genetic defects of greater or lesser seriousness, and all humans must be heterozygous (possessing two nonidentical genes, one from each parent, for a given trait) for at least a dozen or more disadvantageous genes. The speed of accumulation of unfavorable genes in the population de- pends on many factors. Generally, it is a very slow process, which, for centuries, will have no easily recognizable effects. Many a "bad" gene whose effects are overcome euphonically may be said to have lost its "badness," wholly or to a large degree, so that its accumulation no longer represents a serious biological load even though it may represent a con- siderable economic load. Such accumulation may be contained by genetic counseling, which leads some carriers of such genes to limit their families or even to refrain from having children. Genetic counseling can often assure worried persons that their fears of defective offspring are unjustified or exaggerated, but in some instances the predicted likelihood of severely abnormal offspring is high. Knowledge of the inheritance and the variability in expression of the nu- merous kinds of human defects accumulates steadily, and the outlook for improved foundations for counseling is favorable. It will be enormously enhanced as procedures are developed that might make possible positive recognition of those who are asymptomatic heterozygotes for specified undesirable genes. As medical euphonies becomes increasingly successful, it will become increasingly important that genetic counseling be universally practiced. Otherwise, in a few generations, the ethic that guides medical practice will have seriously damaged the heritage of countless previous generations. Having thwarted the historical process of natural selection against such disadvantageous genes, civilization must provide an acceptable substitute. The possibility has been discussed that the great insights of molecular biology may make it possible, in the future, to replace specific undesirable genes in a person's cells with desirable ones brought in from the outside. Several strategies are available, based largely upon understanding of the mechanisms of viral infection. However, many biologists think that the prospects for such "genetic surgery" are doubtful in the foreseeable future. Even if succesful, this would probably simply be a more sophisticated euphonic technique. While there is some possibility that appropriate, de- sirable genes might, one day, be introduced into body cells, it seems unlikely that the new genes could be so inserted into appreciable numbers of germ cells.
Representative terms from entire chapter: