As the following figure illustrates, historically human population has grown very slowly. However, this pattern has been disrupted within the last two centuries by exponential human population growth rates. World population now stands at 6 billion and is projected to continue growing through this century.
This rapid population growth has been associated with global environmental changes including:
Population Energy and Urbanization
Population growth did not occur in a vacuum. It was closely associated with major changes in technology and social organization: essentially with the transformation to fossil fuels and the rise of urban industrial society.
Fossil fuels made possible the rapid
growth of population as transportation cost were reduced and human productivity
Along with population growth came increased demands
for energy, while urbanization and the resulting industrial revolution provided the setting for increased
human productivity. Together, increased energy consumption and population
growth have produced major forms of environmental degradation.
Two Demographic Transitions
To understand this overall pattern of population growth, it is useful to review a basic condition of demographic history, known as the demographic transition: the change of a population from high birth and death rates to low birth and death rates. It is a simple definition, but an exceedingly powerful one, for it shows clearly a major transformation of human reproduction. The demographic transition generally occurs in four stages. In the initial stage, both birth and death rates are high, causing only slow and steady population growth. In the next stage, death rates begin to decline and birth rates remain high, resulting in faster population growth. In stage three, the birth rate begins to decline, and in the final stage, birth rates balance death rates. Population growth stabilizes in this final stage. In some cases, such as Italy, population growth may cease altogether.
The following two charts
illustrate this change.
The Past Demographic Transition
England and Wales experienced a demographic transition characterized by slow and steady change. From 1700, the death rate began a long gradual decline. The decline was initially due to three factors: the first was the trade revolution, which introduced new foods such as potato and maize (corn) from the Americas. The second was the agricultural revolution that brought about higher yields of food production locally through the use of new agricultural practices. Finally, the industrial revolution that made new goods available. All of these changes were gradual, and increased the general standard of living for the population, without major medical breakthroughs. While death rates fell, the birth rates remained high, as both cultural norms and expectations and need for productive labor at home made immediate downward adjustment in the birth rate difficult to attain. As life in an urban industrial society made large families neither necessary for labor nor desirable for cost reasons, the birth rate declined over one or two generations. The intervening period saw a dramatic rise in the annual rate of population growth, to about 1 percent per year.
is important to note that this same transition seen in England and Wales took place in every industrialized
country in the world (all of Europe and Russia, North America, Australia
and New Zealand and Japan). All went from high birth and death rates
in traditional, rural-agrarian societies to low birth and death rates
in modern urban-industrial societies, though the dates and rates of change
The Present Demographic Transition
Today, the same demographic transition is occurring throughout the world’s less developed countries, though the chart shows some dramatic differences with the past transition. First, birth and death rates start at higher levels, for reasons that are not at all clear. Second, death rates have declined much more drastically, moving as much in one generation as it had in the past in two centuries. Third, the cause of the mortality decline lies in the development of new medical and public health technologies, based on anti-bacterial chemicals and insecticides that reduce disease vectors. Rapid mortality declines without concomitant fertility declines means higher rates of population growth are occurring. Where growth rates reached one percent per year in Europe, they have recently reached over 3 percent per year in parts of Asia, Africa and Latin America. The birth rate is now beginning to fall. When this happens, as it has in parts of Asia and Latin America, it can come very quickly, declining from traditional to modern levels in a decade or two, rather than in a generation or two. Along the same lines as the mortality declines, the fertility declines are in large part the result of new medical, mainly contraceptive, technologies.
The mortality declines and the new contraceptive technology have also produced some revolutionary changes in public policy. Up until 1952 most governments of the world were pro-natalist, and were actively opposed to any form of birth control. In 1952 India became the first country to adopt an official policy to reduce population growth by reducing fertility within marriage. This called for the formation of a national family planning program to spread the new contraceptive technology. Since 1952, almost all less developed regions have undergone the same or a similar policy change: they now officially permit or are actively attempting to reduce population growth by reducing fertility.
The results have been mixed. Some countries have experienced a very rapid fertility decline, experiencing a simultaneous substantial increase in the health of women and children. Other countries have made almost no progress. They continue to show high fertility and population growth, along with high levels of maternal and child mortality and very low levels of education and social welfare.
The following charts show another aspect of these mixed results. They illustrate the Total Fertility Rate, or roughly the number of children a woman will bear in her reproductive life.1 China and Thailand show how rapidly the fertility rate can fall. Today all of East Asia has low fertility. Southeast Asia is close behind, as is most of Latin America. Africa, especially south of the Sahara is further behind: most countries still experience high fertility and are just beginning what is expected to be a decline to low fertility.
Costs of Rapid Population Growth
Rapid population growth impedes economic development, helping to keep a country poor, and thus further promoting rapid population growth
Rapid population growth reduces health and welfare, especially of women and children. Rapid growth implies women giving birth from a younger age, experiencing more pregnancies throughout their lives, and bearing children well into their later years. All three are known to cause higher rates of infant and maternal mortality. The first impact of reducing fertility is increasing the health and welfare of women and children.
growth increases number and proportion of young people in the society. This
increases the demand for education and jobs. Where
education and jobs are not available, young people, especially young males, who
constitute a highly volatile population, can
easily be swayed to violence by demagogic leaders.
The following chart shows how fertility is related to the growth of the young (15-19 year olds) male population.
Both Thailand and the Philippines began with roughly the same sized population in 1950, 20 million, of which young males accounted for about 10 percent, or 2 million. Thailand had a slightly lower fertility rate in the 1950s, but the real difference came in the 1960s when Thailand began what has become one of the world’s most successful national family planning programs. The Philippines lagged behind because its family planning program was held hostage to religious resistance. It also had weak overall public services – education, health and other things – held back by a pervasive weakness of government. By 1970 Philippines young males were a third larger in number than their Philippine counterparts (1.7 to 1.4 million). Today (2000) there are 4 million young male Filipinos against only 2.8 million Thais. Which country bears greater costs of providing education and jobs? By 2025, Young Filipino males will number 4.7 million against 2.7 million young Thais. The Philippines is fostering a large cohort of young men who need schools and jobs to keep them in society; without those amenities, this population will be vulnerable to leaders who can use them for their own purposes, ostensibly through providing work and a sense of belonging.
Wealth and Population
growth, urban industrial society, economic development, environmental
degradation, and loss of biodiversity form a seamless web.
Each is both the cause and effect of the others.
None can be effectively addressed in the absence of the others”
(IUCN 1997). We shall
examine some relationships between population measures and economic measures.
These will demonstrate some surprisingly strong relations, which should
not be interpreted as simple cause-and-effect, but rather of the interdependence
of economic development and human population.
But first, a brief digression to define our economic measures.
changed how we think about the measurement of wealth.
In his book, “The Wealth of Nations” (1776), he argued that a
country’s wealth lies not in its gold, but in what it produces.
This stimulated efforts to measure the output of a country, leading to National Income Accounting and the idea of Gross National Product.
He also argued that reducing government restrictions and opening a
country to free trade would help make it wealthy.
Gross National Product of a country is
an estimate of the market value of all the goods and services produced in a
given period (usually a year).
The economy is
circular: the price paid for a good or
service goes to pay the factors that
produced it: Labor
earns wages; capital earns interest; land
earns rent; and entrepreneurship
earns profit. Thus we can add up all the
earnings of the factors of production, and that will (theoretically) equal the
cost people pay for all the goods and services produced.
National or Gross Domestic Product?
For the most
part, we shall treat them as interchangeable, but they are different, and their
differences can be used to examine certain aspects of an economy.
Gross National Product is the sum of all goods and services produced by the factors of production owned by citizens of a nation.
Gross Domestic Product is the sum of all goods and services produced in the territory of the nation, regardless of who owns the means of production that generate the goods or services.
For example, if I invest some money in Mexico and it earns interest for me, it is a part of the US GNP, since it is produced by US owned capital. But that interest is a part of Mexico’s GDP, since it was produced in Mexican territory.
If a laborer comes from Mexico to work in the US, his earnings are part of the US GDP, since they are produced here. But if he sends his earnings back to Mexico, they are part of the Mexican GNP, since they are wages of a Mexican national.
We can compare countries using their GDP per capita (GDP/cap), and this will show that there are many more poor countries than rich countries. Statistically, the frequency distribution is skewed to the low end (think of a grade distribution skewed toward very low grades – but don’t worry, this won’t happen in our course). We often use a log transformation of skewed data to better “see” the pattern, and so we will graph the log (GDP/cap) against some population measures.
the relationship between infant mortality rate and wealth.
Wealth means higher welfare, or lower infant mortality rates.
When looking at such a graph, always ask yourself: (1) what is the
pattern here? (2) what might be the
explanation of outlying points. The
“deviant cases” are those with
higher or lower IMR than expected given their level of economic development.
Using a regression line, the diagonal line across the chart, helps to see
these clearly. A (linear)
regression line is the one straight line that is closest to all of the points on
the chart. Why are Mali and Sierra
Leone higher than expected? Why are
Cuba and Vietnam lower than expected?
is another example: Wealthy countries are growing more slowly than poorer countries.
The problem of population growth is located in the poor countries.
Wealthy countries are growing more slowly because they have lower fertility than poor countries.
Wealthy countries have lower fertility because more of their people are using contraceptives. But also look at the deviant cases. Why is Japan using contraceptives less effectively than expected? Which other rich countries are using fewer contraceptives than expected? How do you explain this? Which countries are using more than expected? How do you explain this?
We close this
lecture by emphasizing that the level of economic development of a country is
intimately related to the status of its human population.
Furthermore, Economic development
has a very large impact on the global environment.
Keep the following ideas in the back of your mind for the rest of the
* Rich countries produce, consume, and pollute far more than do poor countries.
* The rapid population growth of the poor countries is overbalanced by the high individual consumption of the fewer people in the rich countries.
* HOWEVER: Rich countries are becoming more efficient in energy use, and are slowing the growth of consumption. Poor countries are increasing energy consumption and CO2 emissions, and are often getting less efficient in energy use.
Human population rates have skyrocketed within the past two centuries and closely correlate to economic growth and technological advancements. The past demographic transition of the 1800's can be seen in many of today's developing countries, however, population stabilization is occurring at a much slower rate. There has been much concern on the implied socio and environmental impacts of these population growth rates and their entailed consumption rates. Economic measurements, such as GDP and GNP, are possible ways to assess these issues. They can be used as proxies for indicating which nations are in need of the greatest attention for mediation between the demands of a growing population and the pressures put on their natural resources. However, there is much speculation as to how accurate and relevant these measurements are.
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