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Human Ecology

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					Human Ecology
Ecology:
  Ecology is the science of the relationship
   between living organisms and their
   environments.


Human Ecology:
  The interrelationship between human groups
   and their natural environment.
Population
Overpopulation
 The earth's carrying capacity is
 under increasing stress from its
 sheer number of inhabitants.
 Nearly eighty million people are
 added to the world population
 every year, putting additional
 stresses on our planet. By 2025,
 the world population, at current
 rates, will elevate to 8.6 billion
 with the largest impact felt in the
 urban centers of developing
 countries. The combined
 pressures of population growth
 and massive poverty will weigh
 heavily on our stewardship
 potential.
Resource Depletion
          If we choose the wrong path, it is
          the face of innocence that must
          struggle with that which is left
          behind. More than 5,000 species
          become extinct every year - a rate
          10,000 times faster than pre-
          human extinction rates. Half of the
          forests that originally covered 46%
          of the Earth's land surface are
          gone. Here, innocence is wrapped
          in a faded purple blanket - a
          symbol of our diminishing
          prosperity and depleted legacy
          (heritage). What will our legacy
          be?
Extinction of species
             How many species are there?
            The United Nations Environment
            Programme Global Biodiversity
            Assessment estimates the number
            of described species at
            approximately 1.75 million.
            Seventy percent of the world's
            species occur in only 12 countries:
            Australia, Brazil, China, Columbia,
            Ecuador, India, Indonesia,
            Madagascar, Mexico, Peru, and
            Zaire. Rhinos, such as that
            depicted here, are one of many
            species fading into the shadows of
            existence due to poachers and
            habitat loss. Once, dozens of
            types of rhinos roamed the Earth,
            now only five rhino species exist.
            Will we follow the same path?
Hunger and Poverty
           In some areas of our world, each
          day offers only a struggle of life
          and despair. Today, over 1.3
          billion people worldwide live in the
          lowest poverty level existing on
          less than one dollar a day.
          Another 3 billion live on less than
          two dollars a day. More than 1.5
          billion people in developing
          countries have no access to clean
          water. In these regions, there is
          often intense demand on natural
          resources which often translates
          into hunger, famine and even
          death. How can those that have
          so much contribute to the
          solution?
  The Science of Demography
Demography


 The study of the size, composition,
 distribution, and changes in human
 population.
   FROM 200,000 YEARS B.C. UNTIL SEVERAL
    CENTURIES AGO, THE HUMAN POPULATION
    GREW TO 20 MILLION
   THE WORLD POPULATION IN 1995
    • 6 BILLION PERSONS
    • 80 MILLION PERSONS ANNUALLY

   DEMOGRAPHY
    • INTERESTED IN CAUSES AND CONSEQUENCES OF
      GROWTH
    • LET’S EXAMINE SOME OF THE DISCIPLINE’S MORE
      BASIC CONCEPTS
                Fertility
It is the incidence of childbearing in a
society's population.
Women are capable of childbearing from
early teens to usually in the late forties.
During this time, a woman could
conceivably bear more than twenty
children, but this fecundity, or potential
child bearing, is sharply reduced by health,
financial concerns, cultural norms, and
personal choice.
             The Birth Rate

The birth rate (or “fertility rate”) is the

annual number of births per thousand

members of a population.
               Mortality
The incidence of death in a society’s
population.
          The Death Rate

The death rate (or “mortality” rate) is the

annual number of deaths per thousand

members of a population.
INFANT MORTALITY RATES
    • NUMBER OF DEATHS AMONG INFANTS
     UNDER ONE YEAR FOR EACH 1,000 LIVE
     BIRTHS

   LIFE EXPECTANCY
    • AVERAGE LIFE SPAN FOR MALES AND
     FEMALES (1992: 73 FOR MALES, 79 FOR
     FEMALES)
               Migration
It is the movement of people into and out
of a specified territory.
        The Migration Rate

The migration rate is the annual difference
between the number of immigrants
(people entering) or emigrants (people
leaving) per thousand members of the
population
           Age Structure
A society’s age structure is the relative
proportions of different age categories in a
population- is therefore an important
element in predicting demographic trends.
The younger a population is, the more
“momentum” it has for further growth.
     Population growth or decline in a society
      is affected by three factors:


1.   Birth Rate
2.   Death Rate
3.   Migration Rate
History and Theory of Population
             Growth
The World Population Problem
     INCREASES IN WORLD POPULATION
         in Billions by Rich and Poor Country Status
10                                                                               10
 9                                                                                9
 8                                                                                8
 7                                                                                7
 6                                                                                6
 5                                                                                5
 4                                                                                4
 3                                                                                3
 2                                                                                2
 1                                                                                1
 0                                                                                0
     Year 1700 Year 1800 Year 1900 Year 1950 Year 1993 Year 2000 Year 2100




                                                               beyond 1993, projected
     World’s Ten Biggest Cities
           (in millions)
       1900                     2015
London             6.5   Tokyo         28.7
New York           4.2   Mumbai        27.4
Paris              3.3   Lagos         24.4
Berlin             2.4   Shanghai      23.4
Chicago            1.7   Jakarta       21.2
Vienna             1.6   São Paulo     20.8
Tokyo              1.5   Karachi       20.6
Saint Petersburg   1.4   Beijing       19.4
Philadelphia       1.4   Dhaka         19.0
Manchester         1.3   Mexico City   18.8
Malthus’ Theory of Population Growth
   Fact: People must eat.
   Fact: A strong sexual urge drives most people.
   Assumption: While food supply increases slowly
    and arithmetically (1, 2, 3, 4, etc.), population size
    grows quickly and geometrically (1, 2, 4, 8, etc.).
   Assumption: Preventive actions e.g. artificial birth
    control, sexual abstinence (self denail), and
    delayed marriages.
   Conclusion: “Positive checks” are needed (war,
    famine, etc.)
           Criticisms of Malthus
   Technological advances allow rapid growth
    in food production per capita.
   It is unclear what the “natural” upper limit to
    population growth is.
   Population growth does not always produce
    misery.
   Helping the poor does not generally result in
    the poor having more children.
   People have developed and accepted
    contraceptive devices and techniques.
     DEMOGRAPHIC TRANSITION THEORY
    LINKING POPULATION PATTERNS TO A SOCIETY’S LEVEL OF
               TECHNOLOGICAL DEVELOPMENT

   STAGE ONE (PREINDUSTRIAL)
    • HIGH BIRTH RATES DUE TO ECONOMIC VALUE OF CHILDREN
      AND LACK OF BIRTH CONTROL
   STAGE TWO (EARLY INDUSTRIAL)
    • HIGH BIRTH RATE AND LOWERED DEATH RATE GIVE BOOST
      TO POPULATION GROWTH (MANY OF THE DEVELOPING
      NATIONS TODAY MIRROR THIS STAGE)
   STAGE THREE (MATURE INDUSTRIAL)
    • BIRTH RATES BEGIN TO MASK DEATH RATES AS POPULATION
      SURGE DROPS AS AFFLUENCE TRANSFORMS CHILDREN INTO
      ECONOMIC LIABILITY
   STAGE FOUR (POSTINDUSTRIAL)
    • ECONOMIC REALITIES FORCE DROP IN BIRTH RATES TO THE
      POINT WHERE GROWTH IS STAGNANT OR VERY SLOW

				
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