Human Population Size

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Human Population Size
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Questions for Today

• What are the Major Factors that affect Human
  Population Size?
• How are fertility rates analyzed?
• What are the factors that affect Birth and
  Fertility Rates?
• What are factors that affect Death Rates?
• What factors affect Migration?

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Factors that affect Population Size

• There are three factors that affect population
  size
• Births (fertility)
• Death (mortality)
• Migration
• Remember the formula to calculation Population
  Change
• Pop. Change (B I) (D E)

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Population Change

• For the most of human history, the human
  population roughly grew at a slow pace.
• Within the past 200 years, that rate has
  increased significantly.
• Our current rate is roughly, 1.22
• 82 million people were added to the world in
  2008.
• An Average of 225,000 people are added daily
• 2.4 people are added every time your heart beats.
  
• http//www.worldometers.info/

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Population Change

• Three major factors account for this major
  increase
• Our ability to invade new ecosystems and adapt
  fast.
• The emergence of agriculture
• The development of sanitation, antibiotics, and
  vaccines.

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Factors that affect Population Size

• Demographers use the crude birth and death rate
  to calculate population change
• Crude rates are determined by looking at the
  number of births and deaths per 1,000 people in a
  population.
• An estimated and extrapolated number.

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Fig. 6-3, p. 126
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Fertility Rates

• Demographers also take in consideration Fertility
  Rates when calculating Population Statistics.
• Fertility rates are the number of children born
  to a woman during her lifetime.
• Two types of fertility rates
• Replacement-level fertility rate
• Total Fertility rates

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Fertility Rates

• Replacement Level Fertility Rates
• The average number of children that couples in a
  population must bear to replace themselves.
• Ranges from 2.1 in developed countries to 2.5 in
  developing countries.

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Fertility Rates

• Total Fertility Rates
• The average number of children born to women in a
  population during their reproductive years.
• The average world wide is 2.6 children per women.
• 1.6 in developed
• 2.8 in developing

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Factors that affect Birth Rates

• There are 10 factors that affect Fertility rates
• Child Labor
• Cost of raising and Education
• Availability of private and public pension
  systems
• Urbanization
• Educational and employment opportunities for
  women.
• Infant Mortality Rate
• Average age of marriage
• Availability of legal abortions
• Reliable Birth Control
• Religious Beliefs and Cultural Norms.

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Factors that affect Death Rate

• The boom in Human population growth is not
  primarily caused by the birth rate.
• Our Death (Mortality) Rate has significantly
  dropped.
• Death Rates have dropped due to
• Increased Food Supply
• Better nutrition
• Medical Advances
• Improved Sanitation
• Availability of Clean Water

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Factors that affect the Death Rate

• Two statistics used by Demograpghers
• Life Expectancy
• 1955 48 ? 2008 68 ? 2050 74
• Worldwide
• In the US, the Life Expectancy is 78
• Infant Mortality Rate

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Life Expectancy

• Two major factors that affect Life Expectancy in
  the US
• Poor Healthcare across the Nation
• Obesity

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Infant Mortality

• Infant Mortality is one of the best measures of a
  societys quality of life
• Reflects general nutrition and pediatric health
  care
• Three factors affect Infant Mortality Rates in
  the US
• Inadequate Health Care
• Drug addictions among pregnant women
• High Teen Birth Rates

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Migration

• Migration is affected by the economic and social
  problems of other countries.
• Most people leave countries to pursue better
  opportunities in another.
• Jobs
• Healthcare
• Political Opposition
• Religious Intolerance