Human population

1
Human population

• In 1650, human pop. only 500 million
• In 2003, human pop, more than 6 billion
• Increases 90 million every year
• By 2050, could be 10 billion
• How does this impact Earth?
• History
• Thomas More, Utopia, 1500s
• Said ideal state is constant population,
  controlled crops, distribute food in public
  markets and dining halls
• Thomas Malthus, 1798,
• Said populations grow quicker than food supply
• This leads to war, famine, human suffering
• To avoid this, Malthus suggested late marriages,
  and small families

2
Increases in Growth Rate

• Beginning humans were hunter-gatherers, living in
  small tribes, population not known
• Starvation, predation, and disease kept humans
  from living much older than 35
• 10,000-20,000 yrs ago, people began to settle
• These people stored food
• This reduced threat of starvation, and increased
  population size
• Agriculture-10,000 yrs ago began
• Agricultural revolution began-shift from
  harvesting wild food sources to producing food
  through techniques of farming and herding
• More food supply led to population growth
• Standard of living rose

3

• Mortality (death) rate decreased
• Life expectancy increased
• Population about 5-10 million
• Industry-300 years ago began
• Industrial revolution began
• Technology advancements led to
• Improved food production distribution
• Work day shortened
• Safer work environments
• Improved health care and medicine
• Health Care
• 1800s, germ theory occurred- identified bacteria
  and other microorganisms as the agents
  responsible for many diseases
• Before, people did not relate health and hygiene
  as being connected

4

• Germ theory improved sterilizing, waste disposal,
  water treatment
• Also vaccines and antibiotics developed
• These increased birth rates, decrease death rate
• Declines in Growth Rate
• Plagues-decrease populations by large percentages
• Bubonic plague killed 25 of Central Europe and
  Asia
• Famine-lack of food for long time
• Irish Potato Famine of 1840s killed 1 million
• War-many lives killed in short time
• 1/3 of Germany and Bohemia killed during Thirty
  Years War
• WWI killed 21.5 million, WWII, killed 35-60
  million

5
Review Questions

• What was the estimated human population in 1650?
• What is the estimated human population today?
• What did Thomas More say humans should do to
  control the population?
• What did Thomas Malthus say humans should do to
  control the population?
• What kept the beginning humans from growing the
  population?
• How did the agricultural revolution change human
  population standard of living?
• How did the agricultural revolution change
  mortality rates life expectancy?
• How did the industrial revolution change the
  working environment and healthcare?
• What is the germ theory? How did it change
  healthcare?
• What types of things have decreased the human
  population?

6
Growth Changing Needs

• Overpopulation is one of the most serious
  problems
• Measuring population growth is helpful to predict
  changes in the future
• Growth rate is calculated by
• Birth rate (births per 1,000 people) Death
  rate (deaths per 1,000 people)
• Ex Egypt has birth rate 29/1,000 and a death
  rate 8/1000
• 29-821 people for every 1,000 or 2.1
• Doubling time-how long it takes for a particular
  population to double its size
• Mexico City doubled in 10 yrs
• Honduras, Kenya, Syria, Iran, Guatemala doubled
  in less than 30 yrs

7

• Doubling time indicates potential problems for a
  population
• Short doubling time means needing to double
  housing, food supplies, jobs, water, energy very
  quickly
• Immigration/Emigration also effects growth rate
• Immigration-movement of people into an area
• Emigration-movement of people out of an area
• But these do not effect overall earths
  population
• We cant leave the planet, and we dont count
  aliens!!

8
Demography

• Science of the changing vital statistics in a
  human population
• Demographics include age, race, education level,
  income, of children, gender
• Demographics help scientists, planners, and
  politicians make plans for populations
• Changing Needs
• Population size isnt the only thing that
  determines the needs of people
• Changes in technology, lifestyles, standards of
  living affect needs
• Energy consumption increases in industrial areas
  b/c of machinery, not population size

9
Review Questions

• How do you calculate the growth rate of a
  population?
• Williston has a yearly birth rate of 15 births
  for every 1,000 people. We have a yearly death
  rate of 9 deaths for every 1,000 people. What is
  our growth rate?
• What is doubling time?
• What is the difference between immigration and
  emigration?
• What is demography?
• What are two examples of demographics studied?
• What things besides population size effects the
  changing needs of a people?

10
Challenges of Overpopulation

• Rapid growth affects the global ecosystem
• It places greater demand on available land space
• It strains resources minerals, fuels, and food
• Human growth takes away land available for other
  wildlife
• Will humans give up land for wildlife?
• Humans must realize that all life on Earth is
  connected
• Problems with overpopulation
• One countrys overpopulation affects other
  countries
• They have to rely on other countries for energy
  and resources
• Pollution can travel from one country to another

11

• Health problems are linked to overpopulation
• Crowding exposes more people to more sick people
• Malnutrition, poor hygiene, lack of medical
  facilities are greater problems in crowded areas
• Environmental effects are caused by
  overpopulation
• Exhaust fumes from millions of cars causes
  pollution
• Clearing large tracts of land destroys homes and
  breeding grounds of wildlife
• Controlling Population Size
• Obvious answer is to control birth rate
• This is difficult b/c many people do not have
  education and tools needed to control birth
• Even more difficult to convince them it is
  ethical and best to limit family size

12

• Difficulties to control population
• Religion many consider preventing pregnancy
  unacceptable
• Work many families need large numbers to work on
  farms or care for aging parents
• Self-satisfaction many people want children to
  fulfill a feeling of pride and joy in life
• Challenges of low birth rate
• Bulgaria, Hungary, Latvia have birth rates lower
  than death rate
• Now face difficulty finding youth for military,
  workforce
• Have begun to offer financial help to couples to
  have more children

13

• Help from Technology
• Many think that more people means more brain
  power
• Technology will help humans
• New sources of energy, new farming techniques
• Still, the earth can only house a limited of
  people comfortably before it runs out of resources