Transcript Chapter 2 Key Issue 4

Chapter 2 Key Issue 4
Why Might the World Face an
Overpopulation Problem?
Malthus on Overpopulation
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One of the most famous models to explain changes in
population over time was developed by Thomas
Malthus. Malthus was an English economist and
demographer who published his Essay on the Principle
of Population in 1798.
He argued that the world’s population was growing
geometrically or exponentially but food supplies were
only growing arithmetically.
According to Malthus this would lead to “negative
checks” consisting of starvation and disease because of
lack of food. The only way to avoid this would be for
populations to lower crude birthrates.
Neo-Malthusians
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Malthus’ theory is still potentially relevant today
because of rapid growth in some LDCs. His
adherents today are called neo-Malthusians and
are led by Paul Ehrlich, who has made a similar
argument to Malthus in The Population Bomb.
Neo-Malthusians such as Robert Kaplan and
Thomas Fraser Homer-Dixon have broadened
Malthus’ theory to include fuel, agricultural land,
and other resources as well as food.
Malthus’s Critics
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Malthus has critics, too. The Marxist theorist Friedrich
Engels believes that the world has enough resources to
eliminate hunger and poverty if they are more equally
shared.
Contemporary critics include Julian Simon and Esther
Boserup, who argue that larger populations can actually
stimulate economic growth.
Malthus was terribly pessimistic and did not foresee the
development of new agricultural technologies or the
human ability to reduce population growth rates.
Declining Birth Rates
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Most demographers would agree that some parts of the world
are overpopulated, a condition in which a country can no longer
sustainably support its population because it has reached its
carrying capacity.
In human geography the carrying capacity refers to the number
of people a given area can support.
The CBR has declined rapidly since 1990 except in some
countries in Sub-Saharan Africa. This has occurred partly as a
result of economic development, which has resulted in more
money for education and health care.
Birthrates have also lowered because of diffusion of modern
contraceptives. Some countries, such as Bangladesh, have
reduced their birthrates like this without economic development.
There is opposition to birth-control programs from some
countries for religious and political reasons.
World Health Threats
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Medical researchers have identified an
epidemiologic transition that focuses on the
causes of death in each stage of the
demographic transition. Epidemiology is the
branch of medicine which is concerned with
disease.
Epidemiologic Transition Stages 1 &
2
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In stage one of the epidemiologic transition, infectious
and parasitic diseases were the main causes of death.
These include the Black Plague and cholera pandemics.
A pandemic occurs over a wide geographic area, unlike
an epidemic, which is more localized. These causes of
death were most common for people in countries in
stage 1 and the early part of stage 2 of the demographic
transition.
Stage 3 & Stage 4 of the
Epidemiologic Transition
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Stage 3 of the epidemiologic transition is
associated with degenerative and human-created
diseases such as heart diseases and cancer.
As LDCs have moved from stage two to stage
three of the demographic transition, the
incidence of infectious diseases has declined.
Human -created diseases are more typical of
countries in stage four of the demographic
transition.
Stage 5 of the Epidemiologic
Transition
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Some medical researchers have argued that the world is now
moving into stage five of the epidemiologic transition,
characterized by a reemergence of infectious and parasitic
diseases.
This could be for a number of reasons, including the evolution
of infectious disease microbes, poverty, and improved travel.
Avian flu is one of the “new” infectious diseases that has
emerged in recent decades, and it has the potential to become
pandemic.
However, AIDS is the most lethal epidemic of recent years,
especially in Sub-Saharan Africa, where more than 25 million
people were infected with HIV in 2005.