Changes in the size of the population of a given area or society has some important consequences. Rapid growth of the population will place pressure upon the resources (social and natural) needed to support the population. Distribution will also pressure resources, particularly if the population is located where the resources are not. Populations will display characteristic age and sex structures that will further shape what the society can and cannot do. We will briefly describe these general issues and the proceed to an examination of the components of population growth, their interrelations and the effect they have upon the social organization of the society.
Population growth rates are high in some parts of the world and showing no signs of slowing. World population size is approximately 6 billion people with a growth rate close to 2 percent per year (check out the population counter for current and comparative data). Another interesting site (6 billion people) on the web provides additional information about children, allows you to see how many will be alive when you born. This site is maintained by the Musee de l'Homme in Paris.
Western European populations are growing very slowly and in some instances actually declining (Eastern European countries have negative growth rates). Africa, parts of Asia and South America have rates of population growth near 3 percent per year. Such rates are the highest that human populations have seen in its entire history and have serious implications for the resources and our ability to provide for these human beings.
Popnet has links to statistics for a variety of countries in the world. Give them a look.
The resources of the world are concentrated now in the less developed parts of the world, but used in the developed, slower growing populations. As these less developed countries proceed toward modernization, they will want to retain more of the resources for their own uses. In some cases the demand for their resources is actually having negative impact upon the local peoples as in the disappearance of the rain forests in Central and South America. Some countries are very densely populated and though small, have very few natural resources (the Netherlands and Belgium). Others are very sparsely populated and have few resources. The issue is how the population is distributed.
In the United States the disparity between resources and population is most evident when we look at the increasing population concentrations in the West and Southwest and their demands for water. The Denver metropolitan area relies upon the Colorado River drainage for most of its water, but then so do Phoenix, Tucson and Los Angeles. There is simply not enough water in the basin to meet all the needs of these growing population centers.
The age distribution and structure of the population affects the general social well-being of the society. For example, the "baby boom" has stressed American society at every turn. As they passed through the education system, they consistently overloaded it. When they entered labor force, they were hard pressed to find enough new jobs to absorb them. In a few years (2015) many of them will begin to retire and will place a tremendous burden upon the social security, retirement programs and health systems.
Nations with rapidly growing populations have very large numbers of young people that they must educate, feed, cloth and eventually employ (See the United Nations Indicators of Youth and Elderly for comparisons). Countries such as Mexico, for example, have more than half their population under the age of 18. See this projection by the U.S. Bureau of the census, you must pick the country.
Nations with very slow growing populations or ones actually in decline face the opposite problem: a large number of elderly. The demands upon the social and natural resources by these different age structures are quite striking.
I have used the International Data Base created by the U.S. Bureau of the Census to create pages showing these kinds of pyramids. The first pyramid shows the age sex structure of a population (Argentina, 1997) that is growing at a fairly steady rate. The second shows the age sex structure of a population that is rapidly expanding, and the third pyramid shows the age sex structure of a stable or stabilizing population. Each of these is explained with the figures showing the structures..
P2 = P1 + (B - D) + (IM - OM)
These components entirely describe the way in which a population may change over time. A population may be described as open or closed as far as migration is concerned. If the population is "closed," there is no migration in or out of the population. Most national populations are essentially closed, that is they have very limited in or out migration.
Within a nation, migration will be a major component of change. For example, Colorado over the past 20 to 30 years has grown at a rate of 3% per year. This is considerably higher than the rate of "natural increase" (excess of births over deaths) of approximately 1% per year. The difference (about 2%) is attributed entirely to migration.
Migration as a component of change in the population is significant in that it brings (or removes) adults to (from) the population.
examples: For the United States in 1986
For Mexico in 1986
a measure of the number of infant deaths, in most populations this is when the death rates are highest, also where the largest NUMBERS of deaths occur. This is an indicator of the general social well being of a society, since these rates are very much influenced by the distribution and availability of food and health care.
The United States has one of the highest infant mortality rates among the developed countries -- 10.5 deaths per 1000 live births. Compare this figure with Northern Europe: 9 (ranging from a low of 6 to a high of 10 for one country) In contrast the infant mortality is in the range of 35 to 62 in Central and South America, 70 to 160 for African countries.
For example, life expectancy of 75 at birth means that persons born that year will expect to live to 75 on the average.
Life expectancy of 76 years at one year of age in 1991 means that people one year old in 1991 can expect to live to the age of 77 on the average (current age plus the years of life expected).
Pre-modern, pre industrial revolution causes of death:
most caused of death were diseases that affect the very young, in fact the distribution of death rates by age show rates to be quite high for people under the age of 10, the lowest rates are for people between the ages of 15 and about 35, after this rates start to rise again quite sharply.
death rates in these early population were often quite high -- on the order of 25 to 30 or more per thousand population. Causes were primarily due to communicable diseases and especially those that affect children (the young)
Causes of death after the industrial revolution:
Most deaths are caused by degenerative diseases, increasingly so in the latter half of the 20th century.
The decline in the death rates is primarily due to improved sanitation and availability of food. The appearance of cotton clothing meant that the clothes were washed more frequently. Clean drinking water greatly reduced the transmission of diseases such as cholera, typhus and typhoid fever. Vaccinations did play a significant role in this reduction as well.
It is only in the very last part of the 20th century that anti-biotics and other medical miracle drugs have a major impact. For example, the premier anti-biotic, penicillin, was not discovered until the mid-50s.
the census measures migration by comparing where people lived 5 years ago with where they currently live, the categories used are:
Note that in this way of defining a migrant the person must move across some kind of political boundary, at a minimum that of a county line. In Denver you would be a migrant if you moved from the east to the west side of Sheridan, but only a mover if you moved from Inspiration Point to far south east Denver. The first move crosses a county line, the latter is entirely within a single county.
the number of people moving into a given area in a given time period, the rate would be calculated by dividing this number by the population of the receiving area
the number of people moving out of a given area in the specified time period, rate would calculated by dividing the number moving out by the population of the sending area.
Migration is one of the more important components of population change within a nation or a society. There are a number of things that we should be aware of about migrants. First migrants tend to be young and have little in the way of attachment to any given area or community. Men tend to move long distances, women relatively short (when considering the moves of individuals). Most migration occurs around some significant or important change in status or role -- graduation from school (high school or college), entering the labor force, marriage, divorce, retirement. Individual reasons are many and varied, but many can be linked to the broad categories identified above in the "push/pull" of sending and receiving areas. Another point to keep in mind is that there is a kind of social inertia attached to migration -- the longer that someone stays in a given location, the less likely s/he is to move. Much migration and movement is done by people who have already moved within the near past.
Demography places focus upon the elements of the population growth equation and how mathematically each component influences the other. For example, a particular pattern of deaths and births will produce a given age structure.
Demography addresses questions such as the following: How do the birth rates and death rates affect the overall size of the population? What effect do they have on the age and sex structure of the population?
In each case the researcher is looking at the effect of one demographic characteristic on another demographic characteristic.
In social demography the focus is upon the factors and conditions that influence the components of the equation.
Social demography addresses questions such as: How does the social value of children influence the birth rate in the population? How do income differentials and occupational opportunities affect the rates of migration? What effect does the value placed on health and physical activity have on the death rate in the population?
In each instance, these represent social and cultural conditions in the society that affect the demographic conditions.
Limits to growth is a Malthusian problem. Malthus described the manner in which populations grow and how food supply or sustenance grows within a population. His argument is simply that the population is capable of geometric rates of growth (the J curve), whereas the food supply can only grow in an additive, linear manner. Population therefore has the power to rapidly outstrip the ability of an area to support that population. The resources (food, shelter, jobs) therefore place a limit on the size of the population in a given area. For this reason the Malthusian problem is one of resources and how quickly a given population might outstrip those resources.
The available resource place an upper limit on the ultimate size of the population. In some discussions these are referred to as the "carrying capacity" of an area, that is, how many people will the resources of the area support. Carrying capacities are often calculated, but most frequently for plant and animal communities where the food, light and water requirements of the communities are relatively easily established and calculated.
A difficulty arises with this idea in human populations because resources and therefore the carrying capacity are socially, culturally defined. If we consider the area where Denver is located and present the carrying capacity of the region under the kind of social, cultural organization characteristic of the Arapaho (the tribe that inhabited the area before the European settlers came), the carrying capacity is quite small. When the early gold miners came, they brought with them a different set of social and cultural organizations that changed the carrying capacity, permitting a larger number of people to settle in the area. Finally our contemporary social and cultural organization have drastically increased the carrying capacity. Our use of energy, transportation and tunnels mean that we do not have to rely upon the resources in the immediate area to support us.
We should also note that resources are culturally defined. Gold and oil have always existed, but were not considered resources by many early groups.
The Malthusian problem relates to the intersection of "resources" and population growth potential. In the first statement, Malthus argued that the population will grow geometrically: 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024. If you plot these figures you will see what is typically called a J curve. The plot begins with a relatively slow increase that suddenly begins to go up very sharply, producing a curve that looks very much like a J. (Plot the above values on a piece of graph paper so you can see what it looks like -- each value represents a size of the population plotted according the left or vertical axis, the individual values are seen to occur at time intervals of equal size that are plotted along the horizontal axis.) This plot is represented in the following figure:
| * | * | * | * | * | * | * | * | * * | * * | * * * | * * * | _________________________________________________ 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0
(imagine the asterisks in a smooth curve, and you have an idea of the logistic curve)
Malthus saw the available food supply growing only arithmetically: 1, 2, 3, 4, and so on. If these are plotted against the population rates, it is quite obvious that the population will quickly outstrip the available food supply. If you plot these on the above figure you will see the latter produces a straight line and if you begin the line above the J curve, it will eventually intersect the J curve. Where the two lines cross is considered to be an equilibrium point, the point where the capacity to support the population equals the number of individuals present. We could simply plot a horizontal line at this level and that would be a way to indicate the carrying capacity of the area.
When the population outstrips the ability of the area to support it, the only possible biological response is either for the births to decrease (preventive checks) or for the deaths to increase (positive checks). Malthus saw births being limited only by celibacy or abstinence (he was not at all optimistic about the ability of the poor to use either of these methods), so the only alternative is the increase in death rates due to starvation and disease.
This is the Malthusian problem. It is also a solution to the growth problem that most people find unacceptable (i.e., the increase in the death rates). Some also find the alternative solution (reducing births) unacceptable as well.
An increase in death rates or a decrease in the birth rates. Both of these are operable in human populations. China's response to the issue is to limit fertility by forcing families to have only one child. In Africa, the response has been an increase in the death rates because of starvation, malnutrition and the spread of disease in crowded population centers.
The social response involves changing the cultural and social structure of the family or in the definition of the limits. Human populations have as often taken the latter route. The result of this change is to alter the carrying capacity of the region or area.
Take for example, the case of the hunting and gathering society. This level of technology permits only very small, widely dispersed groupings of human populations adjusted to whatever the land is capable of producing. With the discovery of "gardening," the growing of plants for food, a more stable food supply is available and the population grows beyond the limits imposed by the earlier hunting and gathering regimen. Some of these societies become quite large -- on the order of 1 million people. "Gardening" is a technical, social solution to the limit imposed by the natural availability of foodstuffs. With gardening the social group gains some control over the amounts and availability of foodstuff, altering the previous dependence upon the whims of naturally available foods.
The growth of the population in an area becomes a problem as the population bumps against the limits. It then becomes necessary to find a solution to the problem. This solution might be to improve the food production by changing how crops are grown -- instead of "gardening" large scale agriculture with improved irrigation might be put into place. These new technical, social innovations once again alter the limiting factors holding the population in check.
The problem of growth, however, will remain. A typical human solution to this problem has often been to link family formation and therefore reproduction to the ability of the couple to support a family. Thus in many agricultural communities marriage was delayed until the husband could afford his own farm. This effectively reduced the reproductive rate in the community. Such practices were common in much of pre- Industrial Europe and persist to the present in places like Ireland where the median age at first marriage is often in the mid to late 40s for men and 30s for women.
These social, organizational solutions seem to be quite common among human populations. We find many rules and taboos that at first glance seem to have no reason until they are examined as to how the affect the rate of growth of the population.
The demographic transition is a shift in the birth and death rates in a population. Initially, both are quite high and the growth rate is low. For different kinds of reasons (depending upon whether we are talking about Western Europe or the developing regions of the world) the death rates begin to drop but the birth rates remain high. This is a period of high growth. Gradually the birth rates began to fall in Western European countries and the rate of growth slowed. Eventually the birth and death rates became nearly equal and the growth close to zero.
Demographic transition describes the shift in a population from conditions of high mortality and high birth rates to those of low mortality and low birth rates. These changes are attributed to changes in the value of children. Children in the pre-industrial society were seen as an economic asset, as needed to provide for security in old age (large numbers of children were required to produce one or two survivors). With modernization, children become a liability, a consumption item just like a vacation, or an automobile. This idea is helped along by the media in the U.S. when we constantly discuss how much it costs to raise a child (about $2-300,000 per child from birth to about 18 at today's prices).
The transition is this shift from high mortality and birth rates to low mortality and birth rates. Between these two end points there is a period of rapid population growth, since the death rates tended to fall before the birth rates adjusted. The interim period is one of growth and the production of surplus population. The surpluses in Europe were exported to the Americas during the 18th and 19th Centuries. Nearly all of us are products of this export, immigration process. The beginning and end of the transition are characterized by low, very stable growth in the population.
Each phase of the transition is characterized by a different age-sex pyramid. The early phase looks in fact like a pyramid with a wide base and smoothly sloping sides that taper to a point. This early phase population has relatively large numbers of young people, proportionately fewer middle aged and finally only a few very old people. The middle phase is a pyramid with a very wide base, sloping sides that now curve inward and the upward to the peak. This pyramid represents a population that has large numbers of children, some active adults and even fewer old people. The end phase is characterized by a 'pyramid' that looks somewhat like a beehive, the sides are nearly straight up and down, tapering to a point only at the very top (the oldest age groups). This population has about equal numbers of adults and children, with a relatively large number of older people (compared to the previous two pyramids).
The idea of the transition has attracted attention since it points to some interesting structural characteristics in the population such as the ratio of children and old to active, 'productive' adults. Draw each of the pyramids and discuss the ratios as they appear in the pyramids you created.
The European transition began with birth rates in the range of 30 to 35 per thousand population, death rate about 25 to 30 and a natural increase of about 1% per year or less. With the advent of sanitation, and other changes the death rates were gradually brought down over a period of 200 years (transition begins in about 1750) to the current rates of 7 to 12. Somewhat behind the decline in the death rates, the birth rates began to drop, falling eventually to the very low rates now experienced in Europe and the United States (all of these rates are well below replacement, meaning that the populations are not growing, in some cases are beginning to shrink). This low birth rate has only been achieved in the past two to three decades, the latter half of the 20th century. Some typical Crude Birth Rates in this late period of the transition are: 15 for the United States, 12 for Germany. In between the times (1750 and 1950) the European population grew at very high rates (birth rates remained high), the surplus populations were exported to the New World (North and South America).
Industrialization and the reduced demand for children as well as the greater survival of those that were born are given as the reasons for the declining birth rates and the resulting transition to low birth rates. Industrialization and modernization had already given rise to low death rates in these Western countries.
Two things need to be noted for the Third world transition:
Because of the factors above the rates of growth are much more explosive, and the potential problems much greater.
Indications are that the change, particularly the decline in the birth rates are not occurring as rapidly, so the advantage gained by the decline in death rates may be short lived (i.e., the rates are very likely to go back up).
The demographic changes (drop in death rates) have not been accompanied by social and organizational changes that occurred in Europe. That is there is no sizeable middle class in these countries, there is no industrial base to absorb the new citizens, there are not enough schools to train them so education is not rising. All of these factors have contributed to the decline in birth rates in the Western European countries. The absence of these social and organizational changes in the developing world have meant that fertility has remained quite high. For example, when women are educated, they have a greater tendency to participate in decisions made within the family, especially those relating to the number, timing and spacing of births. The net result is lowered fertility for educated women. In the developing countries women are often not permitted to continue or to even get an education.
Take a look at this set of maps showing the growth and distribution of the world's population from 1 A.D to 2025. You should also look at the historic time line that shows events covering this period.
A colleague of mine from graduate school has prepared a series of pages that graphically show some the population changes in the world. For example he has plotted the growth of world population.
here the argument is essentially that the world is overpopulated and is outstripping the available resources, the world and its resources are finite, cannot continue to support the kind of world wide growth that are currently experiencing. You can read the original Essay on Population by Thomas R. Malthus.
Paul Ehrlich and his book "The Population Bomb" is the principal source for the contemporary argument about over population.
not particularly different from above, except that these groups argue for population planning and limitation to family size, through the use of contraceptives.
people of this persuasion do not see a population problem, rather they see a problem of distribution of resources. If there were a more equitable distribution of resources, there would be no poor, starving populations. In other words, "overpopulation" is a matter of how resources are distributed and used. These individuals note that the 'developed' countries comprise about 20% of the world's population but consume over 80% of the world's resources. I have also heard figures that show the United States has about 2-3% of the world's oil reserves but consumes about 45% of the oil available in the world. if these resources were made available to other countries the 'overpopulation' would disappear.
Distribution of the population relates to where the population is located and what the distribution of the resources / wealth is like. Several tables have been prepared that show these distributions in 1977, 1987, 1990 and in 1996. You should look at these and compare the sizes of the populations, their growth rates and their per capita incomes. On the basis of these comparisons think about what the future may hold if these disparities continue or get worse.
This problem is similar to that of 'overpopulation.' However, it does not make any claims about distribution of resources per se. It simply notes that entire continents are made up of countries with very low incomes and very rapidly growing populations. These populations are obviously poor and getting poorer. With large, rapidly growing populations and very little wealth, they are not able to feed, train or support themselves. Compared the per capita income with the size and growth of the populations listed in the two tables.
How populations are distributed across the continents is not the only distribution issue, nor is the rate of natural increase the only growth problem. Both patterns of growth and distribution can be problems within a country, nation or society. The population of the United States is far from evenly distributed, the Eastern states are relatively crowded while many Western states seem to be very sparsely settled.
Colorado provides and interesting kind of statement about distribution and growth rates. First we should note that nearly all of the population of the state is located within a strip 30 mile on either side of I-25, with the bulk of that population located in the Boulder-Denver Metropolitan Area. Growth rates are also very uneven. The suburban counties to the South and East of the City and County of Denver are growing quite rapidly while Denver itself is nearly stagnate so far as growth in size is concerned. The counties on the eastern plains of Colorado are losing population, they are virtually stripped of their young, dynamic people (those with the get-up-and-go got up and went!!).
Such patterns of growth create some serious problems -- the metro area has serious pollution problems directly attributable to the way the city has grown. The suburban communities have problems finding enough classroom space and teachers for their burgeoning population. Some also have very difficult times finding enough baby sitters because of the age distribution in the neighborhood where all of the families tend to be in the same life cycle stage!
The dynamics of population growth and change are extremely important. The age structure of the population is affected by the rates of growth whether due to migration, high (or low) birth rates, or high (or low death rates). The economy in turn is influenced by the age structure. Large numbers of immigrants can strain a society, but it can also bring badly needed new blood and dynamic groups of people. Populations change because of the rise or fall in birth and death rates, the in the flow of people into and out of areas. We have briefly discussed these topics and shown how they affect the social structure of the community.
World Population: A Guide to WWW by Richard Jensen April 2, 1999, prepared for Regents College, New York. This is a pretty comprehensive list of World Wide Web population resources. In fact several of the links above came from this resource.
United Nations Population Guide. This page will connect you to a variety of population statistics for countries of the world that have been prepared by the United Nations.
Social Change Topics
Introduction to Social Change Unit 13: Population Growth and Change Unit 14: Urban Growth Unit 15:Organizational Growth and Change Topical Outline
Copyright © 1996, 1997, 1998, 1999, 2000 by Richard H. Anderson, the Department of Sociology and the University of Colorado at Denver.
This page last revised: November 15, 2000. Please contact Richard H. Anderson (randerso@carbon.cudenver.edu) if you experience any problems or have comments about these pages.