1. Human Population

2. People Over Time
Humans have interacted with their environment in several distinct ways in the past.
The technologies of the time have dramatically influenced these interactions

3. Early Humans
Up until about 500 years ago the human population was relatively stable
Limiting Factors:
Disease
Scarce Food
50% survival of children
During this time frame, human populations had two main modes of life

4. 1. Hunter-gatherer Characteristics: small, migratory groups Effects:
Hunted for game animals
Foraged for seeds, fruits, a vegetables
subsistence - place very few demands on environment, harvest at low levels
Effects:
Sustained prairies with fire, built small dams
Transport of non-native species
Population growth limited by food availability

5. Population was stable

6. 2. Agricultural
After hunter gatherer societies, agricultural societies arose
Agriculture is the practice of growing, breeding, and tending plants and animals (domestication) for consumption or use by humans.
Producing their own plants and animals provided a more dependable supply of food to early humans.
People began living in larger settlements
Effects
human population growth rate increased slightly
selective breeding for desirable traits of crops and animals
habitat destruction for farm land
soil and water degradation as farms replaced forests

9. Slight population increases

10. Industrial Revolution (1800-1900s)
Characteristics:
Energy sources shifted from animals & water to fossil fuels
Mass production of goods rather than small local producers
Increased use of artificial substances… plastics, pesticides, fertilizers
Transportation of goods & people increased

11. Industrial Revolution
Effects:
increased agricultural productivity
improved nutrition, sanitation, medical care
Urban Development- movement of people from agriculture based society to a industry and city based society.
Industrial Growth- increase in the production rates, transport, and consumption rates of goods
increased pollution, growth, and habitat loss
… improved quality of life???

14. Large increase in population

15. Green Revolution
By the 1950’s the world population was growing faster than the food supply
Scientists and Governments got together and developed new, intensive farming practices that increased production of rice, wheat and other key crops- Green Revolution
Monoculture- large fields planted with a single crop year after year
Large irrigation and fertilization and pesticide programs needed to support this type of farming
Allowed food production to more than double, supporting a larger population

16. Population Sky rockets

17. Human population explosion
Just passed 7 Billion last Fall!!!
Characteristics:
Increasing life expectancy
Increasing fertility rates
Increasing need for food/natural resources
Effects:
Human population is 10X larger than 300ya
average population growth rate is increasing
pollution is increasing
pressure on Earth’s environment is increasing

18. Human population growth
Population of… China: 1.3 billion
India: 1.1 billion
1650500 million
20056 billion
Industrial Revolution
Significant advances
in medicine through
science and technology
Bubonic plague "Black Death"
adding 82 million/year
~ 200,000 per day!
Doubling times
250m  500m = y ()
500m  1b = y ()
1b  2b = 80y (1850–1930)
2b  4b = 75y (1930–1975)
The population doubled to 1 billion within the next two centuries, doubled again to 2 billion between 1850 and 1930, and doubled still again by 1975 to more than 4 billion. The global population now numbers over 6 billion people and is increasing by about 73 million each year. The population grows by approximately 201,000 people each day, the equivalent of adding a city the size of Amarillo, Texas, or Madison, Wisconsin. Every week the population increases by the size of San Antonio, Milwaukee, or Indianapolis. It takes only four years for world population growth to add the equivalent of another United States. Population ecologists predict a population of 7.3–8.4 billion people on Earth by the year 2025.

19. Key Factors What are the key factors that have led to the growth?
Reliable food supply
Improved Sanitation
Improved Medication and Health care= decreased death rates and increased longevity
Basically, the limiting factors were removed from the population

20. Demography
In order to better understand how and why our population is changing, scientists study the:
Demographics- study of the characteristics of the population and attempts to explain how the population will change over time
Demographics examines the age-structure of the population
Age Structure- illustrations of the number of people occupying different age groups in the population
Age structures can be used to determine whether a population is likely to grow or shrink in the future.

21. Age Structure Diagrams

22. Age Structure Diagrams

23. Demographic Transition
As countries become more developed their demographics tend to change
Historically, societies had birth rates = death rates
Recently many developing countries have had birth rates > death rates
Most of world population growth is occurring in India and China
Eventually, as countries modernize both birth and death rates fall, and population tends to stabilize
Has happened in a few countries such as Japan, the US and much of Europe

24. Fertility Rates Replacement level fertility:
The number of children per couple that would result in a stable population
2.1 (not all children live to adult hood)
Current:
World 2.47
US 2.06
Japan 1.39
Somalia 6.25
Rwanda 4.81

26. Future? Will this growth continue?
How are humans impacting the environment?
What is the solution?