What Caused the Explosion?

Now that overpopulation has been recognized as one, and not one of the least, of the major threats to the future of the human race, it has become the subject of countless books, articles, television programs, and symposia of all kinds. Yet even now amazingly little attention is being paid to the background and causes of this overriding problem. Only a few of the better texts of modern history give it a paragraph or at most a page, chiefly in reference to the great emigrations from Europe in the nineteenth century.

The problem, in a word, is to explain what can only be described as one of the dominant phases of social development: the abrupt change from an essentially static population, in Europe and probably in other areas, to an unprecedented, precipitate rise. The initial phase of this phenomenal growth antedates the statistical age and has thus far defied treatment in conclusive terms. But the fundamental pattern of growth is no longer the subject of serious controversy. Demographers are generally agreed that the European population, estimated at 140 million in 1750, rose to 188 million in 1800, and to 266 million in 1850. Whereas during most of recorded history the movement of population was so modest and spasmodic as to be unimportant, the fantastic dimensions and the durability of the changes of the past two centuries have created social problems and international tensions that can no longer be ignored or slighted. The Reverend Thomas Malthus, who in 1798 first sounded the warning and expounded “The Principle of Population,” recognized the danger of over-population, but regarded it as a distant eventuality. Yet today the Malthusian prognostications seem mild. The threat of overpopulation stalks at our heels like an ominous specter that may be upon us within a paltry generation or at most two.

Within recent years certain historians and economists have joined forces in the effort to grapple with the basic problem of the so-called “population explosion.”^* These scholars have done fascinating work with parish registers and other local records and have taught us much about birth and death rates, about family sizes and organization, about marriage rates and other aspects of social life, such as the numerous checks to population growth and the prevalence of celibacy. But long series of parish registers are rare and it is highly unlikely that enough information can be derived from them to provide a firm foundation for the history of the population even of Western Europe, where reliable, systematic demographic data rarely antedate the mid-nineteenth century.

Certain influences on the movement of population have, of course, long since been recognized. Throughout history famines have been common and have been followed usually by epidemics and by the endemic “killer” diseases that were the bane of human existence. It was only reasonable, then, that Malthus and his contemporaries should have attributed the past drain on the population to such natural disasters, along with man-made restrictions on marriage and inheritance. Nature, in other words, had ensured that the normally high human birthrate should be counterbalanced by a high death rate.

Some twenty years ago Dr. Thomas McKeown, at present professor of social medicine in the Medical School of the University of Birmingham, together with his associate R.G. Brown, published an article in Population Studies (IX, 1955) entitled “Medical Evidence related to English Population Changes in the Eighteenth Century.” Their essay was directed at the valiant but unpersuasive thesis of G.T. Griffith: Population Problems of the Age of Malthus (1926, 2nd edition 1967), in which the author, starting from certain suggestions contained in Malthus’s writings, argued that in the England of the eighteenth century improvements in public health (advances in medical knowledge, improvements in hospitals, more substantial housing, better water supply and sanitation) had contributed heavily to a sharp decline in the death rate and had thereby brought on the striking increase in the population. Dr. McKeown brought his professional competence to bear on this phase of the problem and so completely demolished Griffith’s thesis that it has since been generally abandoned by other students of the problem.

Now, after the publication of several further essays, Dr. McKeown has published a more extended monograph, adducing much new data and, above all, employing a new approach to the old problem. In the reviewer’s opinion this is a most important contribution, in fact the most convincing and enlightening treatment of the subject yet available.

Any effort to summarize the data or the arguments in this modest volume would do it a grave injustice. Suffice it to say that Dr. McKeown is fully conversant with the extensive and diffuse literature of the controversy, and takes it into account. Furthermore, though the nature of the sources obliges him to refer chiefly to the English experience, he makes every effort to encompass the entire Western world and, wherever possible, to reach out to other parts of the Old and the New worlds.

A large part of Dr. McKeown’s book concerns the major diseases, their character, spread, mortality, and therapy. What is new here is especially the line of attack: since vital statistics for the late eighteenth and early nineteenth centuries are scant and usually unreliable and hence useless, the author argues that much could be learned of the history and treatment of the great infectious diseases in the pre-statistical period by analyzing the data and studying the incidence and effects of these diseases as they appear in the records of civil registration in England after 1838.

This procedure leads him to the conclusion that the great mortality of the “killer diseases” such as plague, typhus, tuberculosis, cholera, scarlet fever, and measles was due almost entirely to infection, the nature and forms of which he discusses at length, yet without becoming hopelessly technical. His conclusion is that even such therapeutic methods as inoculation and vaccination for smallpox were at best of limited effectiveness, not to be compared with modern methods of surveillance and containment. Though himself a physician, he feels impelled to say that human control of most diseases hardly antedates the introduction of sulfa drugs and antibiotics in the 1930s. Even the interested layman is bound to be shocked when told (p. 108) that the records indicate that between 1848 and 1971 vaccination against smallpox accounted for only 1.6 percent of the decline in the English death rate.

Having disposed at some length of the well-worn notion that the great increase in population after about 1760 was due largely to the mysterious disappearance of plague in Western and Central Europe, to the supposed control of smallpox through inoculation and vaccination, to advances in medical science and practice, and to growing attention to public health, Dr. McKeown faces the further task of finding a different and more plausible explanation of the population explosion that baffled and alarmed Malthus and his friends.

Two unrelated and generally neglected factors are adduced by Dr. McKeown as probably important contributing items in the modern rise of population. Recent monographs have thrown interesting light on both these factors and their importance is stressed by Dr. McKeown. The first item is the decrease and eventual disappearance of infanticide in most of the world. The second deals with the relationship between food supply and population growth and the nutritional changes of the period here under discussion. A brief review of these factors is essential to an appreciation of the present state of the issue.

The subject of infanticide is so abhorrent to Christian thought that no comprehensive, systematic study of it has ever, to the reviewer’s knowledge, been undertaken. I refer here not to cases of individual child murder, usually by young girls or women who have been seduced by their masters or employers and who, terror-stricken and desperate at the approach of the unwanted child, resort to any one of many forms of criminality in disposing of their infants. Such cases have been fairly common throughout the centuries and have furnished novelists with one of their most alluring themes. But no one would contend that these cases, interesting and pathetic though they may be, were ever numerous enough to affect the general birthrate. The real problem concerns legal, or at least socially acceptable, infanticide, widely practiced with the full intent of restricting the number of newborn babies.

Among the Greeks and Romans the destruction (usually at birth) of unwanted female children was routine practice to which no stigma and no sanction was attached. The Greek philosophers considered it sheer folly to permit the population to rise beyond the capacity of society to support it, and the Roman upper classes were most reluctant to marry and establish a family, preferring to adopt a son if the disposition of their estate required one. In the Orient, among the Chinese, Japanese, and Indians, or at least among certain tribes, it was customary, as the Japanese peasants put it, to “thin the rows” of the population much as one thinned the rows of growing vegetables. Where infanticide was the accepted practice it was unusual to see families with more than two or possibly three children. Without a doubt, infanticide was a most effective method of keeping the population within bounds.

The Fathers of the Christian Church broke with ancient practice in this regard. They denounced infanticide of any kind as murder, and throughout the Middle Ages and the early modern period women discovered as guilty of the crime were punished by incredibly atrocious though highly imaginative execution. But against what may be called clandestine infanticide the Church was quite helpless, for it was a crime easy to commit and extremely difficult to prove. What was to be done to poor parents who claimed that they had accidentally “overlaid” their infant child while in their sleep, or had unwittingly smothered the babe with a pillow, or been unable to provide it the proper food, or, finally, had ignorantly given it an overdose of laudanum as a pacifier?

It is impossible, in a review, to pursue this fascinating problem in detail, but the reader may be reminded that covert forms of infanticide, together with exposure, concealment, and drowning, had by the eighteenth century become so common that in many countries private or public foundling hospitals and other refuges were hastily established. Unfortunately it soon turned out that they, too, led to abuses of many kinds and that “baby farming” came to be a flourishing trade. Not until the latter part of the nineteenth century was repressive legislation enacted and even at that time probably because the rapidly growing use of contraceptives obviated the need for such drastic methods of population control. In Dr. McKeown’s, as in the reviewer’s, opinion, the role of infanticide in limiting the growth of population prior to the nineteenth century has been overlooked or grossly underestimated.

The relationship between the food supply and the movement of population was not unfamiliar even in the days of Gibbon and Malthus. Any peasant could tell you that without food you could not live and that with too little or too poor food you might well contract some mortal disease: “Famine is almost always followed by epidemical diseases,” says Gibbon in discussing the so-called “plague of Diocletian,” “the effect of scanty and unwholesome food.” Modern researches suggest that malnutrition reduces fertility as well as raising liability to infection. On the other hand, Dr. McKeown notes, where the death rate is high a relatively slight improvement in the living standard will be quickly reflected in a growth of population.

The problem confronting us is to explain how the English population, for example, which increased from roughly nine million in 1800 to roughly eighteen million in 1850, could have been fed. It is known that the food consumed by Englishmen in this period was predominantly home-grown. Even in 1850 the importation of food from abroad, which had begun in a modest and spasmodic way about 1785, was still relatively unimportant. Clearly there must have been a truly impressive improvement in the agricultural productivity of the country during the century under consideration. In the past much was made by some scholars of the so-called “agricultural revolution,” that is, the development of crop rotation, drainage of lowlands, better manuring, construction of granaries, the building of canals and roads, etc. We may readily concede that the number of “improving landlords” was constantly increasing and that there was indeed a significant rise in productivity. But it can hardly be claimed that such advances were sufficient to explain a doubling of the food supply. James Caird, writing of English agriculture after a careful survey in 1850, leaves no doubt that for the most part it was still what it had been for ages past and that England was only on the threshold of the modernization of agricultural technology.

The answer to the question seems to be that the accretion in the food supply was due largely to the rapid spread of the culture of that “miracle vegetable,” the potato, which had been brought to Europe from the Andean highlands by the Spaniards in the sixteenth century but had for long been looked upon with suspicion and grown mostly as a curiosity. Ireland appears to have been the first country to recognize its unusual nutritious and other virtues and to have grown it in quantity from the seventeenth century onward. By 1800 the majority of Irishmen were living almost exclusively on the potato and by the time of the great famine in 1846 there was no doubt whatever that the island had become hopelessly overpopulated.

Meanwhile on the Continent the potato had been adopted in various parts of Germany and the Low Countries. It was already well-known at the time of the great famine of 1709, and during the Seven Years’ War foreign soldiers, prisoners in Germany, had come to appreciate it. By the time of the famine of 1774 several governments undertook to propagandize in its favor. While conditions naturally varied from place to place, it may fairly be said that by 1800 the potato had become the principal food of the lower classes almost everywhere in northern and central Europe, while in the southern countries and the Mediterranean area maize (Indian corn), also a Spanish import from America, played an analogous role in vastly enlarging the food supply. Since everywhere the potato continued to flourish even in times of cereal crop failure, it became a vital factor in the economy.

Dr. McKeown takes full account of the food supply, as of the decline of infanticide, in his discussion of the modern rise in population. There are other, lesser factors that might be considered, but for the most part they are obscure. An example would be the history of contraception, which probably played an important role in replacing infanticide and abortion. The case for the potato and maize is easier to identify and defend, but systematic histories of these lowly foods remain to be written. Meanwhile Dr. McKeown’s critical analysis of the unprecedented and precipitate rise in the human population marks an important step toward solution of a thorny problem. His book is a distinguished piece of scholarship, consolidating, as it does, the findings of several different disciplines and adding thereto his own unrivaled knowledge and keen imagination in dealing with social problems. His book is one of the truly important books of our time and it richly deserves world-wide interest and attention.