The modern expansion of world population.
The attempt is made in this discussion to portray the dimensions of the modern growth of world population against the background of previous long-range trends, to show how the trend has evolved during the last 2 centuries in the world as a whole and its major areas, and to consider some possibilities with regard to its continuation in the future. The world population in the middle of the 18th century is estimated at about 800 million. Compared with the United Nations 1965 estimate of 3281 million, the "low" estimate for 1750 indicates a 5-fold increase and the "high" estimate an increase of more than 3-fold during the last 2 centuries. Available data suggest that accelerated growth problems began somewhat before 1750 in parts of Europe, Russia and America and possibly before 1700 in China. 2 phases of the world population trend since the 18th century can be distinguished: a phase of growth at relative moderate speed from 1750 to 1900 and a phase of sharply accelerated growth since 1900. The question arises as to what is the explanation for the apparent and approximately simultaneous upturn of the population during the 18th and early 19th century, in widely separated regions of the world where economic conditions and developments were diverse. The question requires some new research directions. 1 suggested direction is the study of worldwide epidemiological and economic repercussions of the European voyages of discovery and conquest from the 15th century onward. Since the beginning of the present century, the former ambiguous relationship between economic development and population in different areas has been transformed into a strong inverse relationship. Since 1900 the less developed areas have borne almost the entire responsibility for speeding up the expansion of world population in the 2nd phase, while growth in more developed areas has proceeded at a relatively steady if not slackening pace.