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 Links
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Drylands: The Aral Sea The United Nations Homepage U.S. Census Homepage Internet Population Resources Family Planning councils of America |
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| Introduction |
| Demography |
| History of Population Studies |
| Some Basic Foundations of Demography |
| Demographic Measures |
| The Demographic Transition |
| Ecology |
| The POET Scheme |
Introduction: Population and the Environment
- The basic theme here is the relationship
between population growth and natural resources.-- Too much growth strains
our supplies of natural resources; the struggle for increasingly scarce
resources further strains our social existence. Competition between
the east and the west; developed and developing nations-- involves (to
a large extent) conflict over limited resources. (Even for such "unlimited"
resources as nuclear energy, there is intense debate-- Chernobyl is an
example-- because of the potential damage that can be inflicted on the
environment).
- For example, the United States
with approximately 6 percent of the world's population, consumes about
35 percent of the world's resources in energy and minerals.
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Demography: The study of Human Population
- Demography is the scientific
study of population size, composition, and distribution.
- It examines both population STRUCTURE
and population PROCESS.
- STRUCTURE
refers to
- size of population
- composition of population
- age and sex characteristics
- racial and ethnic characteristics
- distribution of people within a territory
- fertility-- birth rates
- mortality-- death rates
- migration-- movement from one locality to another
PROCESS refers to growth, decline, and movement
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History of Population Studies:
- Demography is not new: From antiquity
rulers needed information about their subjects, usually it was very simple
information-- a head count, or "CENSUS"
- For example: the number of able-bodied
men who could fight in the army; the number of subjects who could be taxed;
etc.
We find several occasions in the OLD TESTAMENT describing censuses counting and registering people, e.g.
- Numbers 1-- (At Mt. Sinai when
the Israelites left Egypt)
Ezra 2-- (At the end of the 40-years wandering of the Jews)
- Luke 2:1-- The emperor
Augustus ordered a census of the empire for tax purposes. This is why Joseph
and Mary went to Bethlehem-- to be counted in this census.
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Some Basic Foundations of Demography
Ibn Khaldoun (1332-1406): Arab social philosopher living in the 14th century studied population and developed a cyclical theory of population growth.
John Graunt (1600's):
British haberdasher and clothier took an active interest in population
in the 1650's and studied fertility, mortality, and migration by amassing
data from church parish records on christenings, births, deaths, and burials.
He published a study (1652) listing his findings:
- In the city of London, deaths exceeded births. In the surrounding countryside the opposite occurred.
- The number of males at birth exceeded the number of females. (This is the sex ratio at birth).
- He computed a mortality table for the city of London.
- He discussed migration, fertility, and mortality as components of population growth.
- Food production increases arithmetically-- 1,2,3,4,5,6,7,8, etc.
- Population has the potential to increase geometrically-- 1,2,4,8,16,32,64,128,256, 512,1024....etc. Starting with one amoeba, for example, you can end up with 67,108,864 in just 27 generations.
Edmond Halley (1656-1742),
British Astronomer, also dabbled in demography producing a life-table
for Breslau, Germany.
Thomas Malthus: The
most lasting and noted contributions have been made by an English clergyman,
Thomas Malthus (1766-1834) who published his ESSAY ON THE PRINCIPLE
OF POPULATION in 1798. In this work he outlined what has come to be
called, the "Malthusian Dilemma."
- The PREVENTATIVE CHECKS; (Birth control through abstinence-- Remember, Malthus was a clergyman).
- The POSITIVE CHECKS; (famine, war, pestilence, etc.)
- Karl Marx (1818-1883)
never a demographer, wrote an influential response to this argument stating
that it was basically capitalist propaganda designed to further subjugate
the working classes by limiting their population growth and political power.
Under socialism and communism, there would be more efficient modes of organization
that would distribute wealth more fairly throughout society. There would
be no shortages of food and natural resources according to Marx, if his
model of social organization were adopted.
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Measures of Fertility, Mortality, and Migration:
- Fertility:
- Crude
Birth Rate (CBR): the number of live births per 1000 population
in a given year (usually the population at mid-year serves as the basis).
- It is "crude" because it takes
the entire population into account, not just the "population at risk" or
women who are in the child bearing ages of 15-44.
- It ignores the age structure
of a population.
- Example: CBR, USA (1992) was
approximately 16 (16 per thousand population). GFR, USA (1991) was approximately
70 per thousand women aged 15-44 years old in the population.
Further example: During the Great Depression (1935) in the USA, fertility was low and the CBR was 19; In 1967 after the baby boom (1946-1965), fertility was high, but the CBR was less (18)! (Does this mean that women were having more babies during the Depression? No! Why not? The population, in 1967 was filled by young baby boomers who had not had their children. Compare GFR and we are not mislead: GFR, USA (1935) = 78; GFR, USA (1967) = 88.
- Total Fertility Rate (TFR):
the number of live births to a woman over her child bearing years. In USA
(1993) TFR = 2.0 births. (In 1982 it was 1.8; in 1955 it was 3.6. In Ethiopia
it is over 7).
- Mortality:
First, we need to distinguish MORTALITY from MORBIDITY. MORBIDITY
refers to measures of disease and illness in a population. They can be
very specific, e.g. the incidence of AIDS in a population. Don't confuse
morbidity with MORTALITY or the actual deaths that occur.
- Crude Death Rate (CDR)--
the number of deaths per 1000 members of a population. (In 1991, the U.S.
had a CDR of 9 per thousand population).
Age-Specific-Death Rate-- the number of deaths per 1000 members of a SPECIFIC AGE GROUP in a given population.
Infant Mortality Rate--
This is regarded by many as the best overall indicator of a society's level
of general health. It is defined as the number of deaths to infants (less
than 1 year old) per 1000 live births in a given population. The infant
mortality measure also is a good indicator of a population's future growth
rates.
- But this may not operate in a
"common sense" or "logical" way. For example low infant mortality would
lead one to conclude that a population has a high rate of growth since
more infants will survive, eventually reaching the point where they will
have children themselves. However, looking at world data, we find that
high infant mortality rates are accompanied by very high birth rates and
populations that grow faster.
- Example: The USA: Infant
mortality rate = 8.8 (1992)-- (Rate of natural increase .6 percent); Mexico:
Infant mortality rate = 29 (1991)-- CBR = 29 (Rate of natural increase
2.4 percent) Given these growth rates, it will take Mexico approximately
29 years to double its (1991) population of 90 million. (The USA would
require 116 years to double its population with a rate of natural increase
equalling .6 percent per year). [The "Law of 70"] However, our actual growth
rate is 1.1 percent (due to immigration which yields a doubling time of
64 years).
- Migration:
- The Crude Net Migration Rate--
the net number of migrants in a year per 1000 people in a population. [((Total
number of in-migrants minus the total number of out-migrants)/ total midyear
population) multiplied by 1000.
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The Demographic Transition:
- Historically, this refers to
the gradual decline in birth and death rates that occurred during the period
from the late 1700's to the mid 1900's in the industrialized (western)
world.
- Death rates fell slightly more
quickly than birth rates, leading to a growth in population.
- High Birth Rates/High Death Rates
- Declining Death Rates/High to Moderate Birth Rates
- Low Birth Rates/Low Death Rates
- This growth was spread over a
longer period of time (150+ years) while the world still had plenty of
frontier for colonization. This lessened the impact of population growth.
- Modernizing countries (the third
world), however, have undergone this process in a much shorter time period
(1920's to the present) resulting in an explosive growth of population
at a time when the world's frontiers have dwindled. This has placed tremendous
pressure on the environment.
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Ecology:
- Ecology is the scientific study
of the relationship between organisms and their environment. Modern
environmentalism differs from conservationism of the past.
Environmentalists are really ecologists in that they emphasize the impact
of changes in population, technology, and social organization on the environmental
system.
- Example: Build a coal-fired
power plant in Tennessee and all states down wind from it will be impacted
- Example: set aside a part of
the forest while permitting extensive logging in another part. (Environmentalists
concerned with the impact of logging on the environment as a whole).
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The "POET" scheme:
- This is an ecological model--
(functionalist)-- that emphasizes the interrelationship between four variables--
Population; Organization; Environment; and Technology:
According to the Malthusian model, the population "explosion" will have
dire consequences on the environment. Marxists argue that changing
the form of social organization from capitalism to communism could control
the impact of population growth on the environment. (History
has not supported this claim as Marxist societies have abyssimal environmental
records; e.g. the former Soviet Union).
Thus far, the "green revolution"
representing advanced technology in food production has enabled food supplies
to keep ahead of population growth. (The horrible famines of recent in
Africa resulted from politics involving food distribution, not a shortage
of food supplies). Technology also has been used to develop cheap and effective
methods of birth control which can be used to control population growth.
Technology also increases the amount of damage that can be inflicted on
the environment-- nuclear power is the most often cited example.
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Organization
Population
Environment
Technology
- Sociologists argue that "Social
Organization" is a critical variable in this model. As previously
mentioned, famine is just one social problem caused by politics, not a
lack food. The use of birth control is another issue where a safe, effective
technology exists, but politics determines whether or not a society will
endorse it. The environment, itself, has become an intensely political
issue-- if social groups do not resolve their differences regarding the
environment our future prospects may be dim, indeed.
Finally, it may appear that the environment is treated as the dependent variable in this model-- this is not the case. Major environmental changes will have a tremendous impact on all the remaining variables in the model. ("El Nino" is a very recent example of a global environmental condition that has had a very significant impact on human living conditions). For example, we are very close to knowing for certain whether or not a "green house" effect is already under way-- (the green house effect is currently regarded as a "political issue" by many of those holding power in our society). If such a phenomenon does occur, we are bound to see an intensification of efforts to counter its effects. (We've already placed restrictions on industrial emissions, automotive exhausts, coolants like freon, etc.)
The former Soviet Union provides an example of how human engineering on a massive scale can disrupt the environment with diversion of water flow into the Aral Sea and the nuclear disaster at Chernoybl.
Links
to related web sites:
Drylands:
The Aral Sea
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