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POPULATION GROWTH OVERPOPULATION UNDERPOPULATION

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POPULATION GROWTH OVERPOPULATION UNDERPOPULATION Powered By Docstoc
					   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
    access to imported food, do not have the
    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………….
Some contradictions in population
           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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