Transitions in World Populations

Unless we know the size,density,age distribution,and reproductive capacity of a population,it is difficult to understand many aspects of its society,politics,and economy.In the contemporary world,most nations conduct periodic censuses to assess the present situation of their populations and to plan for the future.Before the mid-eighteenth century,when census taking became a regular procedure,population estimates and counts were sporadic and usually inaccurate.Thus,arriving at estimates of populations from the past,especially for non-literate societies,is a highly speculative exercise in which archaeological evidence and estimates of productive capacity of agricultural practices and technology are used. The earliest date for a population estimate with a margin of error less than 20 percent is probably 1750.

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The history of human population can be divided into two basic periods:a long era-almost all of human history-of very slow growth,and a very short period-about 250 years from the mid- 1700s to the present-of very rapid growth.Before agriculture was developed,the hunting-and-gathering economies of the world’s populations supported 5 to 10 million people,if modern studies of such populations can be used as a guide.After about 8000 B.C.E., when plants and animals were domesticated,the world’s population began to increase more rapidly but still at a modest level.Although agriculture provided a more secure and larger food supply,population concentration in villages and towns would have made people more susceptible to disease and thus reduced their numbers.Some historians also believe that the settled agricultural life also led to intensified warfare (because of the struggle for land and water) and increasing social stratification within societies.

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Still,the Neolithic revolution,the shift from hunting-and-gathering to settled agricultural life,stimulated population growth.It was the first major transition in the history of world population.One estimate, based on Roman and Chinese population counts and some informed guesses about the rest of the world,is an annual growth rate of about 0.36 per million.By 1 C.E.,the world population may have been about 300 million people.It increased between 1 C.E.and 1750 c.E.to about 500 million people.We should bear in mind that during this period of general increase,there were always areas that suffered decline, sometimes drastic,because of wars,epidemics,or natural catastrophes,such as the disastrous decline of American Indian populations after contact with Europeans,caused by disease, conquest,and social disruption.

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A second and extremely important transition took place between the mid-seventeenth and the mid-eighteenth centuries.Initially based on new food resources,this transition often is associated with the Industrial Revolution,when new sources of energy were harnessed. The growth rate greatly increased during this period in the countries most affected.Between 1750 and 1800,the world population grew at a rate of more than 4 percent a year to more than a billion people.By the mid-twentieth century,the world growth rate had tripled,and by 1990 the world population had risen to more than 5 billion.

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This demographic transition took place first in Europe and is still more characteristic of the developed world.Most pre-modern agrarian economies were characterized by a balance between the annual number of births and deaths;both were high.Life expectancy usually was less than 35 years,and the high mortality was compensated by high fertility;that is,women had many children.Improvements in medicine,hygiene,diet,and the general standard of living contributed to a decrease in mortality in the eighteenth century.This allowed populations to begin to grow at a faster rate.By the nineteenth century in most of Western Europe,the decline in mortality was followed by a decline in fertility.In some countries such as France, these two transitions took place at about the same time,so population growth was limited.In much of Europe,however,the decline in fertility lagged behind the decrease in mortality,so there was a period of rapid population growth.Until the 1920s,population growth in Western Europe and the United States was higher than in the rest of the world,especially in the less industrialized countries.In recent times,that situation has been reversed.?

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?Unless we know the size,density,age distribution,and reproductive capacity of a population,it is difficult to understand many aspects of its society,politics,and economy.In the contemporary world,most nations conduct periodic censuses to assess the present situation of their populations and to plan for the future.Before the mid-eighteenth century,when census taking became a regular procedure,population estimates and counts were sporadic and usually inaccurate.Thus,arriving at estimates of populations from the past,especially for non-literate societies,is a highly speculative exercise in which archaeological evidence and estimates of productive capacity of agricultural practices and technology are used.?The earliest date for a population estimate with a margin of error less than 20 percent is probably 1750.