DECREASING AND INCREASING RETURNS 11 1. Estimates of the world's population. 11 2. Population growth in Europe since 1800. f 3. Increase since 1790 in America. f 4. Relation of population to resources. 5 5. Birth rates. f 6. Death rates.
7. Population growth and intensive cultivation. 5 8. Law of increas ing and decreasing returns. I 9. Increasing returns in the nineteenth century. § 10. Rhythmic changes of population. 11 11. Cumulative dy namic economy. § 12. Individual and general adjustment to static con ditions. § 13. Adjustment to dynamic forces. Note on Various mean ings of diminishing returns.
§ 1. Estimates of the world's population. The move ment of population can be known with approximate accuracy only where a census of the population is regularly taken. This was done nowhere until the end of the eighteenth cen tury, and even now is done for only a small part of the world. In all other places and times, movements of population can only be estimated, usually from very insufficient data. It is certain, however, that in ancient times a considerable density of population was attained only in a few centers of empire (Egypt, Babylon, Persia, Greece, Rome, etc.), where peace, trade, fertile soil, comparatively advanced methods of agri culture, accumulated wealth, and extended political power with tributes from subject people were combined in an ex ceptional degree. Nearly the whole of the habitable globe was possessed by hunting tribes or by pastoral nations very sparsely peopling the lands. It has been estimated that the population of the earth at the death of Augustus (19 A.D.) was about 50 Since 1800 there is more of knowledge 1 The Italian economist Bodio's estimate is 54 million.
428 and less of guess work in the figures, which have been esti mated as follows: Repeating the warning that these figures are mere esti mates, it may yet be believed that a great increase had taken place between the first century and the year 1800, of which a large part, about half, had been in the Chinese Empire, numbering then about 300,000,000 people. But the most enor mous increase occurred between 1800 and 1910, about one billion people being added to the world's population, the total in 1910 being nearly three times as great as it was in 1800.
The population of Europe is said hardly to have exceeded 50,000,000 before the fifteenth at which time Eng land had about 2,500,000 people.* Population grew rapidly
from the end of the fifteenth century with the increase of centralized government, better agricultural methods, foreign trade, inventions, An enormous loss of life took place on the Continent during the Thirty Years' War (1618-1648), still a term of dread in Germany which, during that time, lost 2 The first column was compiled from various authorities by Prof. W. F. Willcox, in his paper "The Expansion of Europe"; from which we have derived the yearly arithmetic increase and percentage of increase by decades.
Mulhall's "Dictionary of Statistics." • At accession of Henry VII, 1485 A.D. See Train's "Social England," vol. III, p. 129.
through violence, pestilence, and famine about two thirds of its former population. Despite numerous wars the popula tion of Europe, according to a widely quoted estimate, was 130,000,000 in and was about 175,000,000 in § 2. Population growth in Europe since 1800. Popula tion increased in Europe at an unprecedented rate in the nine teenth century. It numbered about 175,000,000 in 1800, over 250,000,000 in 1850, about 390,000,000 in 1900, and 400, 000,000 in 1910. Many things helped to increase the food supplies available for Europe. The resources of the Amer ican continent were hardly touched until the great western movement of population began and new agencies of trans portation brought American fields thousands of miles nearer to European markets. The improvement of machinery and of other economic equipment in Europe, and better methods of cultivation aided to increase production rapidly. Popula tion followed, tho not with equal step. The increase has gone on at undiminished pace in eastern and southeastern countries but recently there has been a notable decline in the rate of increase in several of the countries of western Europe. France has been nearly at the stationary stage since the be ginning of the twentieth century, and England probably will have reached it by the middle of the century. The great war begun in 1914 must, in the warring nations, greatly reduce the marriage rate, increase the death rate, and reduce the birth rate, until the end of hostilities. The men killed in battle are fewer than the children never to be born, who but for the war would have come into the world.