# POPULATION GROWTH OVERPOPULATION UNDERPOPULATION by wulinqing

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```									   POPULATION
GROWTH
OVERPOPULATION
UNDERPOPULATION
TERMS
   Demographic equation
   Population momentum
   J-shaped curve
   S-shaped curve
   Homeostatic plateau
   Carrying capacity
   Malthusian and neo-Malthusian
   Population policies: Eugenic, pro-natalist,
expansive
What causes growth?
   Growth is due not only to natural population
increase, but to immigration and emigration,
and changes in life expectancy.
   For example, in the United States the NIR is
.6%, with a doubling time of 117. But when
immigration is added, the overall growth
rate is 1.2% with a doubling time of only 58
years.
The demographic equation

   This is a formula for determining the overall
growth rate of a REGION:
   It takes into account the natural change
(difference between births and deaths) and the
net migration amounts (difference between in-
migration and out-migration).
Demographic Equations
Growth Rate (%) = Birth Rate – Death Rate +/–
Migration
ON A GLOBAL SCALE,
ALL POPULATION
CHANGE IS DUE TO
NATURAL CHANGE!
Population momentum
   Even if fertility rates decline, the numbers of
births can continue to grow.
   If the cohorts at the bottom of the population
pyramid are large, those young people will
eventually enter their reproductive years, and
will in turn have children.
Population Momentum
What is doubling time?
   The amount of time it takes for a population to
double.
   This will of course vary as the TFR varies: an
increase in the TFR causes the doubling time
to drop dramatically.
Examples
Limits on population growth

 According to Malthus, population
would increase geometrically while
food production could only increase
arithmetically.
 Thus war, famine and disease act as
checks on population growth.
However…………
   People are continually replaced. For
everyone who dies, many more are born:
There were about 70 million deaths in all
of humankind's wars over the past 300
,

years, which still is less than a 1-year
replacement period at present NIR.
Exponential growth (J-shaped
curve)-- Assumes no limitations on
resources.
.
S-shaped curve
The top of the S-curve
represents a population
size which is supportable
by the resource base.
When population is equivalent to the
carrying capacity of a certain area, it is said
to have reached a homeostatic plateau.
Homeostatic populations
Population Growth
Exponential vs. Logistical Growth
What is overpopulation?
A value judgment which reflects a
conviction that an environment or territory
is not able to adequately support its present
population.
*It is not only due to numbers but also to
carrying capacity: maximum number of
individuals an area can support on a
sustained basis given the prevailing
technology.
   Carrying capacity is related to the level of
economic development: how the
population is able to make use of the land.

   MDC’s, with better resource usage and
same experience with population density
as LDC’s.
Neo-Malthusians
   Policy makers began to realize they needed to
not only lower death rates, but also foster a
decrease in birth rates: this came to be known
as Neo-Malthusianism.
   Programs are aimed to limit population
through birth control and family planning.
Types of government policies
   Expansive population policies: Communist
countries such as Russia and China, as well as
the Nazis, encouraged large families in the
past.
   Now some European countries are doing so
again, with tax incentives and other measures,
to counter their aging populations.
Pro- natalist policies
   Policies which are intended to encourage the
population to increase the birth rate; I.e.
increase the population.
   These types of policies would be implemented
in Stage 4 countries where the birth rate has
been declining.
   E.g.: Russian Day of Conception
•An opposite approach is a eugenic
population policy, such as the way
the Nazis treated „mental defectives‟,
the Jews and others.

Some have accused Japan of this
type of policy due its discrimination
against non-Japanese, with tax
incentives and the allocation of its
resources.
   Lastly, there are restrictive policies,
such as are now pursued in India
and China, and which range from
the tolerance of birth control on the
low end of restriction to the
prohibition of large families or the
one-child policy of China.
The “Oops” Factor
   Sometimes population practices have
unforeseen consequences.
   Sweden promoted increasing the CBR,
only to have to deal with an increase of
children in one small cohort, and then the
subsequent decrease as their economy
faltered.
   Now they are talking about having sexy TV
programs on at night to………….
policies:
   Or—what about the friction of distance? Is it
always relevant?
   Despite the Roman Catholic Church’s opposition
to birth control, the countries nearest the Vatican
have the lowest CBR.
   Meanwhile—the Philippines, very far from
Rome, are experiencing growth of 2.2%. Church
and state have fought over the issue, and the
church appears to be winning.
An example in Islam:
The opposite effect
   In Saudi Arabia where Mecca is located,
there is 3% growth rate, one of the world’s
fastest rates.
   Yet in Indonesia, the growth rate is only
1.6%: Muslim leaders objected to birth
control, but the government was able to
negate their influence and institute a family
planning program.
Was Malthus right?
   Some feel that the Earth’s capacity is far
greater than we think.
   Others argue that it is like a spaceship
with finite capacities, citing problems like
air pollution, malnutrition, starvation,
deforestation, etc.
   Either the increase in the global population
proves the failure of natural controls to
limit births or to increase deaths, or………
Or are we smarter than he
thought?
   People have been able to circumvent
those natural controls:
 Slowing population growth

 Control global population numbers.

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