Fig. 6. Growth of the Population of the United States (After Pearl)

      We may similarly project it into the past. France, for example, is an old nation; but we lack reliable census data for France before 1800. Data available since then, however, are sufficient to create the segment of a curve which may be projected backward as well as forward. The curve for France’s present cycle of growth had practically reached its upper limit in prewar days, and suggested decline. The period of time required by a given nation to go through the familiar pattern of growth varies greatly. With France, the period seems to have been something over four centuries for its current cycle. But records for Algeria convinced Pearl that this one small country had lived through almost a complete cycle of growth, from youth to maturity, in less than a hundred years — that cycle com prising the period of open French control following conquest, which seems to have been completed around 1850 (see Fig. 8).

      Fig. 7. Growth of the Population of France (After Pearl)

      This leads to another striking observation. Algeria was an old country, with an indigenous population, before it was brought under French domination. The introduction of French control apparently launched a new cycle in the nation’s life. Alterations in the environment were sufficiently radical to permit a new cycle of population growth to superimpose itself on whatever old one had existed — one for which we have no census records. When the new trend began, it followed exactly the pattern of expansion we are now familiar with in other countries.

      We may thus reach an interesting observation. New cycles of growth may be superimposed upon old ones. We cannot predict when this will happen. Nor can we, as regards humanity, predict the conditions that permit it to happen. But a new cycle can appear when some fundamental change occurs.

      If we put our colony of Drosophila into a larger bottle, with greater food supplies, a new cycle of growth would begin, but with a pattern quite similar in shape to the old. Similarly, a nation can apparently effect, through a reorganization of its resources, a change in environmental essentials which accomplishes much the same end. It seems to be established, for instance, that the introduction of an industrial economy permits a new rate of population growth substantially in excess of that which was sustained by the community when it was dominantly agricultural.

      Fig. 8. Growth of the Indigenous Native Population of Algeria (After Pearl)

      The world has striking evidence of this in the case of Russia, which following 1917-1918 entered into a new growth cycle. In terms of this new cycle, Russia stands today as the youngest of the great nations in the world. The United States is comparatively an old nation, in the sense of the dynamic forces that are reflected in a rate of growth, biologically and industrially.

      Fig. 9. Growth of the Population of Germany

      This chart (after Pearl) makes apparent two cycles of growth which have overlapped during the period of census history.

      Pearl was convinced that a similar new cycle was once evidenced in Germany, where census records go back far enough to permit him to find a modern cycle of growth superimposed on an old one In the first half of the nineteenth century, Germany’s population was reaching the upper level of growth in a cycle that had prevailed since the 1600's. For years the nation had been predominantly agricultural. The abortive democratic revolution of 1848 was coincident with the beginning of a new industrialization, conducted under Prussian leadership, and new political forms. In the twenty years that followed 1850, this industrialization reached a development that permitted the swift defeat of France in 1870. The further unification of Germany that Bismarck then imposed seems merely to have added impetus to the new growth in strength already then established. These events were almost immediately reflected in a rapid increase in the population’s rate of growth. The upsurge was clearly in evidence by 1870, and subsequent census figures demonstrated that a new cycle of growth had begun, as shown in Fig. 9.Germany’s new pattern of growth, following 1850, demonstrates an interesting and perhaps significant point, when her population chart is compared with those for England, France, and the United States: Germany in 1914 was in one sense the youngest of these four industrialized nations. This may help account for the extraordinary vitality evidenced by the German people in their rapid rise from their 1918 defeat — one which hardly disturbed their social integration. What it may mean hereafter is wholly problematical, since today’s Germans, living in the world’s greatest mass of ruins, seem only individual remnants or survivors of a population that no longer is a united nation.

      For our own purposes here, the past pattern of Germany’s population growth is worth noting only because it leads to a conclusion which Pearl phrases succinctly:

      When human social evolution does manage to put a kink in the curve of population growth, it has not done it by altering any biological law. It merely shifts, by a greater or smaller amount, the absolute base from which the law operates. Then the process goes on as before.*

      [* Ibid. p. 20]

      It is possible to draw another conclusion from which Pearl abstains, but which seems inherent in the data available to us. The renaissance in the pattern of growth apparently does not occur, except concurrently with revolutionary changes in the environment. In viewing the United States, we have no grounds for believing that the prevailing trend in our population growth will undergo any material change, unless we simultaneously have grounds for believing that a great revolution in American affairs is due — and a revolution, at that, complete enough to permeate our political, economic, philosophic, and social institutions.

      This is exceedingly important to understand, for it has further implications. We are going to discover that patterns of growth in human organisms — an organism like a group of workers associated in an industry — look and act very much like the patterns or trends in population growth. And, in further similarity — these patterns show what we might call an “urge to fulfillment.” That is, they are consistent; they do not change capriciously; and there seems no reason to expect any change unless we also imply a revolution in the constitution of the organism, or in the environment where the pattern is being worked out.

      It may well be that our discovery of a new source of energy, such as has been revealed to us by nuclear physics, or some of our revolutionary new advances in chemistry, which in effect give us new sources of raw material, do herald a fundamental revolution in our society. For instance, Dr. Hornell Hart, Professor of Sociology at Duke University, who believes many of the activities of the human race can be fitted to the Pearl logistic curves, suggests that harnessing of atomic energy may mean a steep upward swing in some of our familiar graphs.* Others may find themselves inclined to agree with him. Some hope, similarly, that the United Nations is a precursor of a new form of world government that could release wholly new energies in our nation. But it would be some time before we could be statistically sure of any such change. When a new trend line is superimposed on an old one, the rise will seem to immediate observers like a mere rise in the cycle that rides on the trend. Some years would have to pass before we could be certain that any such rise is not just cyclic in character, but amounts to a rise in the trend line itself — the imposing of a new, rapidly rising trend line on the old.

      [• American Journal of Sociology, June, 1946.]

      This much is worth noting: changes that accompany a new rate of growth in any given society are so profound, and so all-reaching, that old established institutions undergo a severe shake-up. This shake-up will be in evidence long before we get the statistical data to show what is really happening. It is not impossible that the economic and social upheavals being experienced by our own generation are the foreshadows, as it were, of revolutionary changes that ultimately will give us