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Overpopulation may indicate any case in which the population of any species of animal may exceed the carrying capacity of its ecological niche. In common parlance, the term specifically refers to the relationship of human population
to the planet Earth.
Malthus's theory
Early in the 19th century, Thomas Malthus argued in An Essay on the Principle of Population that, if left unrestricted, human
populations would continue to grow until they would become too large to be supported by the available agricultural land. He
proposed that that while resources tend to grow geometrically, population grows exponentially. At that point, the population
would be restrained through mass famine and starvation. Malthus argued for population control, through "moral restraint", to avoid this happening.
Over the two hundred years which followed, famine has overtaken numerous individual regions; proponents of this theory state
that these famines were examples of Malthusian
catastrophes. On a global scale, however, food production has grown faster than population. It has often been argued that
future pressures on food production, combined with threats to other aspects of the earth's habitat such as global warming, make overpopulation a still more serious threat in the future.
Perhaps the best-known example of such an argument is The Limits to
Growth, a report produced for the Club of Rome in the early 1970s.
The optimist's viewpoint on population growth
Other studies have countered with the claim that the current population level of over six billion may be supported by current
resources, or that the global population may grow to ten billion and still be within the Earth's carrying capacity. Buckminster Fuller and Barry Commoner were both proponents
of the idea that human technology could keep up with population growth indefinitely. The assumptions that underlie these claims,
however, have been strongly criticised.
In any case, many proponents of population control have averred that famine is far from being the only problem attendant to
overpopulation. These critics point out ultimate shortages of energy sources and other natural resources, as well as the
importance of serious communicable diseases in dense populations and war over scarce resources such as land area.
Fossil-fuel subsidies in agriculture
One of the strongest criticisms of an optimistic outlook is that of the fossil
fuel subsidy of modern agriculture. The extremely high agricultural outputs of modern farms depend entirely on immense fossil
fuel (mostly petroleum) subsidies in the forms of fertilizers, equipment fuel, and other chemicals such as pesticides. With proven reserves of petroleum steadily falling from year to year, fossil-fuel subsidies would seem to be
ultimately doomed.
Effects of unregulated population growth
The world's current agricultural production, if it were distributed evenly, would be sufficient to feed everyone living on the
Earth today. However, many critics hold that, in the absence of other measures, simply feeding the world's population well would
only make matters worse, natural growth will cause the population to grow to unsustainable levels, and will directly result in
famines and deforestation and
indirectly in pandemic disease and war.
The demographic transition
However, others contend that within a generation after the standard of living and life expectancy starts increasing, family
sizes start dropping in what is termed the demographic
transition. In support they point to the contention that every estimate of maximum global population since the 1960s, when the "population explosion" became a worry, has been significantly lower than the
previous estimates. Among those holding this view are the ecologist Paul Colinvaux, who writes on the topic in Why Big Fierce
Animals are Rare, and The Fates of Nations.
The status of women
Another point of view on population vs. the standard of living is that of Virginia Abernathy in Population Politics,
in which she shows evidence that this effect only holds true in nations where women enjoy a relatively high status. In strongly
patriarchal nations, where women enjoy few rights, a higher standard of living tends to result in population growth. She argues
that foreign aid to poor countries must include significant components designed to improve the education, human rights, political
rights, political power, and economic status and power of women.
"Survival of the fittest"
Some approach overpopulation with a "survival of the
fittest," "laissez-faire" attitude, arguing that if the Earth's ecosystem becomes overtaxed, it will naturally regulate
itself. In this mode of thought, disease or starvation are "natural" means of lessening population. Two particular objections to
this argument are that a) in the meantime, a huge number of plant and animal species become extinct, and b) this would result in
terrible pollution in some areas that would be difficult to abate.
Others argue that economic development is the best way to reduce population growth. Many developed countries in the world
today, such as Italy, now have declining populations (ignoring the effects of immigration).
In either case, it is often held that the most productive approach is to provide a combination of help targeted towards
population control and self-sufficiency. One of the most important measures proposed for this effort is the empowerment of women
educationally, economically, politically, and in the family. The value of this philosophy has been substantially borne out in
cases where great strides have been taken to this goal: where women's status has dramatically improved, there has generally been
a drastic reduction in the birthrate to more sustainable levels. Other measures include effective family planning programs, local renewable
energy systems, sustainable agriculture methods
and supplies, reforestation, and measures to protect the local environment.
American immigration policy
Some overpopulation activists have taken the position that population growth must be dealt with on a country-by-country basis,
and therefore support a reduction in immigration into some countries, including the United States, in order to stabilize their
population. Others disagree with this approach and believe that population should be addressed only as a global issue, through
birth control, family planning, and empowerment of women, not through immigration restrictions. Among the groups who take a
position in support of immigration reductions is Negative Population Growth; among those who do not take a position on immigration
and concentrate instead on birth control and family planning is Population Connection,
formerly Zero Population Growth.
This debate has spread to the broader environmental movement. The Sierra
Club has been the subject of a recent internal debate over whether to support immigration restrictions in the United States in order to curb population growth in the U.S. Proponents
of this policy point out that the native-born population of the U.S. has achieved stability or even negative population growth,
and that the population growth in this country is due solely to immigration and to the fact that immigrants, on the average, have
much larger families than native Americans.
In 2004 proponents of this change were roundly defeated in a member ballot.
Overpopulation as a social issue
The density of population has an impact on a broad range of social and economic issues, such as land prices and housing costs.
For example, relatively densely populated countries such as Japan have higher land prices
than less densely populated countries such as Australia, and even in that
country, land prices have doubled and redoubled as the population has increased. It is sometimes argued that reducing the
populations of some areas, such as large cities, would have positive benefits for these reasons.
Pet overpopulation
A different overpopulation concern pertains to the population growth of domestic cats and
dogs, often among strays. Many groups such as the Humane Society urge pet owners to have their pets spayed or neutered in order to prevent pet overpopulation.
Pet overpopulation can be an ecological concern as well as a concern over animal welfare, with overpopulation occurring when
there are more domestic cats and dogs than there are people wanting them as pets, independent of ecological carrying
capacity.
See also
External links
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