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Demography Powered By Docstoc

   Population trends in history
    – The demographic transition
   Contemporary demography
    – The rich and poor world divide
   Implications of demography for society
Population trends in
   For most of human history on earth,
    the population was stable at about ten
    million people or so
   It did not start to rise until about 8000
    BC and reached about 500 million in
   In 1650 it began to rapidly increase
Why did that happen?

   Before 1650 mortality and fertility
    rates were both high.
   Since 1650, mortality rates fell but
    fertility stayed high – hence the
    increase in population.
   Today world population stands at 6.8
    billion people
    So why did mortality start to decline
    in 1650?
   Decline of infectious diseases –
    typhoid fever, diphtheria, scarlet fever,
    TB, dysentery, typhus.
   Great reductions in mortality among
    the young. Why?
Improvements in Public
   Better public health – especially
    cleaner water (without added
   Better practices at home – use of
   Agricultural production increased in
    western Europe after 1650, and that
    meant more food for people and for
   Better nutrition – more meat,
Plus better practices at
   Hand washing before eating
   Clothes washing – helped by
    introduction of cotton clothes
   Widespread use of soap in 19th
        As a result, people got

Increase in
height and
among U.S.
Then something even
stranger happened…
   People stopped having so many babies
    in the late 1800s in Europe, a little
    later in the U.S.
   Families started getting smaller
   Birth rate fell from 30-40 babies born
    per 1000 people before 1900 to 14.16
    babies born per 1000 people in 2007
Photo of the Sociologist Kenneth Westhues German grandparents in
1896, posing with their first eight children in front of their
antebellum American home
The sociologists Joseph Whitmeyer and Rosemary Hopcroft and their family,
December 2009
Why the decline in
   Industrialization meant more people
    working in industry not on farms
   Especially if work required literacy,
    children became more of a cost as
    they had to be sent to school rather
    than helping on the farm.
   Decline in child mortality meant that
    people did not have to have lots of
    children to make sure some survived.
   This entire process – the fall in death
    rates, followed later by the fall in birth
    rates, is called the demographic
Stages of the
demographic transition
   Many non-European countries have
    gone through a demographic transition
    in the last 50 years.
   Fertility is now quite low in most of the
    world except Africa.
   Countries that have high fertility rates
    contribute disproportionately to the
    growth in world population.
The rich and poor world
   In poor countries, men can expect to
    live until they are 63.5 years old,
    women can expect to live until they
    are 67.5
   In rich countries, men can expect to
    live until they are 73.5 and women
    until they are age 80.
   People in poor countries are most
    likely to die of infectious diseases,
    people in rich countries are most likely
    to die of heart disease and cancer.
   A population pyramid shows the
    number of people in different age and
    sex groups in a population
   Population pyramids in poor countries
    look like pyramids
   Population pyramids in rich countries
    look like posts
Implications of
demography for society
   A young society works very differently
    to an old society.
   Many young people mean many jobs
    catering to the young (e.g. education)
   Many old people mean many jobs
    catering to the elderly (e.g. nursing
   The U.S. had a fairly youthful
    population in the 1950s and 1960s due
    to the baby boom.
   As the baby boomers age and retire
    beginning in 2010, there will be a
    large group of elderly people in U.S.
   This is likely to strain programs for the
    elderly such as Social Security and
Other implications of
   Age and sex structure is also
    important in small groups such as
   Groups where the average age is
    younger operate differently to groups
    where the average age is older
   Population growth can have adverse
    effects on the environment
   It is a concern for the world, because
    we do not know how many people, at
    what standard of living, the world can
   Immigration tends to bring people
    from poor countries into rich countries
   Generally this is not a problem in good
    economic times
   In bad economic times, anti-
    immigration sentiment is the likely
Demography and the
democratic process
   In any democracy, any group that is in
    the majority tends to dominate the
    democratic process
   E.g. large numbers of older people
    generally mean that politicians pay
    attention to policies that benefit the