Human Population

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Human Population

• Environmental Science

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What is a Population?

• Population- all the members of a certain species
  in a certain area.
• Human population- All the members of the human
  race on Earth.
• Why on ALL of Earth?
• Humans have used technology to adapt and be able
  to easily move from anywhere on Earth to anywhere
  else.

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Population Changes

• Populations grow when the birth rate is greater
  than the death rate.
• Birth rate-number of organisms reproduced in a
  year
• Death rate- number of organisms that perish in a
  year

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Population Change

• Populations can decrease if the death rate is
  greater than the birth rate.

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Limiting Factors to Population Growth

• Limiting Factor- Anything that limits how many
  individuals a certain population will have
• Food supply- If theres not enough food for every
  organism to grow and carry out life functions,
  then some organisms will die
• Space-If there isnt enough habitat, some
  organisms will die
• Predation/Disease- If there are no
  predators/disease, a population can increase

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White Tail Deer

• Around 1900, the white tail deer in NY population
  was very low.
• Due to almost no habitat, and unregulated human
  hunting
• Efforts were made to limit hunting
• Forest habitats started to increase as
  agriculture in NY decreased
• Now, in 2008, the white tail population is
  enormous
• Due to regulated hunting and no natural predators
• Abundant food sources and a TON of habitat

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Carrying Capacity

• Carrying capacity- The total number of
  individuals that a certain habitat can support
  and sustain.
• Carrying capacity is based on the limiting
  resources of a given habitat.
• When a population exceeds its carrying capacity,
  it will rapidly decrease (crash) until it is
  below the carrying capacity

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Easter Island

• The inhabitants of Easter Island were so numerous
  that they used up all of their resources.
• When the resources were all gone, many people
  killed each other for the scarce food and water
  that was left.
• Other people starved, until the population was
  very, very small

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Human Population Growth

• With the invention of new technologies, the human
  population has exploded from just 200 million
  8000 B.C. to 6.6 billion today.

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Human Society

• Human Society has changed over time
• Hunter-Gatherer Society- Humans lived in small
  bands and spent most of their time looking for
  food
• Agricultural Society- Humans spent time in small
  cities and towns, in one place, and spent most of
  their time growing food.
• Industrial Society- Humans live in larger
  communities, but can freely travel, and spent
  most of their time pursuing money, rather than
  food.

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Human Population Growth

• There are three stages of population growth
• 1. Pre-agricultural societies birth rate and
  death rates are high, but close to equal, so the
  population grows slowly
• 2. Agricultural societies population size
  increases due to an increase in health care
  resulting in higher birth rates and lower death
  rates.
• 3. Industrial society-Birth rates fall until they
  are roughly equal to death rates, resulting in
  zero population growth.

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Why the changes in population growth?

• Agricultural population increases because level
  of health care increases, but the birth rate
  doesnt decrease. In an agricultural society,
  children are an asset.
• Industrial The population levels out and stops
  increasing because of advances in technology, but
  also because children become economic
  liabilities, rather than assets.

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Population Pyramid

• Population Pyramid a graph showing the number of
  males and females in each age group in a
  countrys population.

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Japan

• Japans three population pyramids shows the three
  kinds of population growth.
• 1950- Rapid growth, the birth rate is greater
  than the death rate.
• 2006- Slowing growth, the birth rate is greater
  than the death rate, but not by much
• 2050- Zero growth, or negative growth, the death
  rate exceeds the birth rate.

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Japan
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Problems with Population Growth

• Pollution- increased people means more pollution
• Shortage of natural resources- As more people
  consume more and more, we will run out of some
  resources
• Space-Where will we put all these people and
  still have lands to support them?

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Solutions?

• We need to consume less!
• Work for a sustainable future.
• Sustainable- being able to support a certain
  population indefinitely