Human Population Issues

• Birth rate: # of live births per 1000 people
  • (# of births) / (total population at midyear) x 1000
    
    
• Death rate
  • (# of deaths) / (total population) x 1000
    
    
• Industrialization
  • developed and undeveloped countries
    
    

• Population Growth: Status
  • Initially slow growth of human population
    • Predators
      
      
    • Disease
      
      
    • Insufficient food
      
      
    • It took 3-4 m.y. to reach 500 million population in ~1650 A.D.

• Improved agricultural methods, the industrial revolution, exploration/emigration to new lands
  • 1 billion people by 1830 (doubled in 180 years)
    
    
• Public health measures, immunization, reduced infant mortality, insecticides (DDT)
  • 2 billion people by 1930 (doubled in 100 years)
    
    
• 4 billion people by 1976 (doubled in 46 years)
  
  
• Present world population: 5,800,000,000 people
  
  
• World population currently doubling every ~45 years
  
  
• 8 billion people by 2021?

• Population growth (where?)
  • Developed, industrialized nations
    • Europe, USA, Canada, Japan, etc.
      
      
    • Decreased birth rate and death rate
      
      
    • Demographic Transitions
      
      
• Developing nations
  • Former European colonies, independent after WWII
    
    
  • Rapid decrease in death rate
    
    
  • Increased population growth rate
    
    
  • 1940: 2/3's of world's population
    
    
  • 1990: 3/4's of world's population

• Highest population growth rates in:
  • Africa, Southwest Asia, Latin America
    
    
  • these countries have the highest growth rates, and lowest gross national product (GNP)
    
    
• Population related societal strains
  • Imbalanced distribution of wealth
    
    
  • Gross National Product (GNP) per capita
    • Less than $500/year for half the world's population
      
      
    • Greater than $20,000/year for 10% the world's population
      
      
    • Population growth rate inversely proportional to wealth!
      
      

• Food supply
  • Over 50% of world get less than 100% of required calories
    
    
  • Over 25% of world get less than 90% of required calories
    
    

• Populations and Trophic Levels
  
  
• What will happen next?
  • Population Pyramid: The Age-Gender Structure of the Population
    
    
• With growth, there is environmental degradation
  • Increased resource consumption
    
    
  • Increased pollution
    
    
  • Decreased natural habitats
    
    
  • Increased crowding/urbanization
    
    
  • Inadequate individual food, space, and resources
  • Infectious diseases
    
    
  • Violence and warfare
    
    
• Good news about population problem
  • World growth rates declining since 1970's
  • Why?
    • Governments involved in family planning
      
      
    • Economic development (locally)
      
      
    • Lower mortality rates -> decreased number of children
      
      
    • Better education
      
      
    • Higher status for women

• Demographic Transitions
  • Stage I
    • high death and birth rate; no population change
      
      
  • Stage II
    • high birth and low death rates; large population growth
      • Industrial Revolution
        
        
  • Stage III
    • low birth and death rates: population growth slowed
      
      
  • Stage IV
    • birth and death rates equal: no population growth