1. Chapter 7
The Human Population

5. Earth’s Carrying Capacity
The human population is increasing exponentially
Exponential growth continues until environmental limits are reached
Competing theories exist regarding the ability of humans to alter these limits, and therefore the carrying capacity of the Earth

6. Earth’s Carrying Capacity
1798: Thomas Malthus
Postulated that the human population would outgrow our ability to produce enough food
Agricultural land is finite
Food supplies increase linearly if no innovation occurs to produce more food

7. Earth’s Carrying Capacity
1950s: Green Revolution
Dramatically increased grain production through the development of new agricultural technology and techniques
Variations of this process have happened periodically throughout human history

8. Demographics Study of factors that drive human population growth
Basic factors
Immigration
Emigration
Crude birth rate CBR (# births per 1000 people)
Crude death rate CDR (# deaths per 1000 people)

9. Global Population Growth Rate
Assumption is that no immigration to or emigration from the planet occurs
Divide by 10, as CBR and CDR are out of 1000 people, to express as %
= (CBR-CDR)/10
=(20-8)/10
=1.2%

10. National Population Growth Rate
Includes immigration and emigration
=(CBR+immigration) – (CDR+emigration)/10

11. Doubling Time
Rule of 70 can provide a precise or an approximate doubling time
If the growth rate is constant, then the rule of 70 is more precise
If the growth rate changes, then the rule of 70 provides an approximation

12. Fertility and Birth Rate
Total Fertility Rate (TFR)
Estimated # of children each woman in a population will have
Replacement-Level Fertility
# of births required to offset deaths
Must take into account pre-reproductive mortality
Individuals who die before reproducing
In developed nations, it is 2.1
In developing nations, it is higher

15. Replacement Level Fertility Issues
When TFR is at or very near 2.1, and immigration and emigration are balanced, then a population is stable
When TFR is less than 2.1, and immigration does not fill the gap, the population will shrink
When TFR is above 2.1, and emigration does not increase, then the population grows

16. Life Expectancy
Average number of years an individual can expect to live in a particular country
Often different for males and females
Many factors influence life expectancy
Healthcare
Nutrition
Pollution exposure
Wars and conflicts

17. Infant and Child Mortality
Infant Mortality
Number of deaths of children under 1 year old per 1000 births
Global rate is 46
Child Mortality
Number of deaths of children under 5 years old per 1000 births

18. Infant Mortality Trends
Low in developed nations, high in developing nations
US Liberia 99
Sweden Bolivia 50
Can be different from national averages in different regions or cross-sections of a country
African Americans 13.6
Native Americans 13.6
Caucasians 5.8

19. Aging and Disease Both affect the death rate
A large elderly population increases the death rate
Disease also increases death rate
Heart disease, cancer
Infectious disease
HIV/AIDS, malaria, tuberculosis

20. Age Structure
Describes how a population is distributed across age ranges for each gender

21. Age Structure Types Population Pyramid
Lots of younger individuals, fewer older individuals
Typical of developing countries
Shows population momentum, or why a population will continue to grow even after birth control measures are instituted

23. Age Structure Types Population Column Population Inverted Pyramid
Even distribution of individuals in all age groups
Shown in developed countries with a TFR near replacement, or lots of immigration
Population Inverted Pyramid
Few younger individuals, lots of older individuals
Shown in developed countries with a TFR below replacement

25. Migration Can contribute to a country’s population growth or decline
Net migration rate
Difference between immigration and emigration in a year per 1000 individuals
Immigration – emigration/1000 = NMR
Positive rates indicate the population is growing
Negative rates indicate the population is declining

26. Do The Math p. 187 Calculating population growth from migration
Assumes TFR and net migration are constant
Also assumes that TFR = replacement
When will population double, based on migration?
Must first find the growth rate based on migration
migration growth rate is 2/1000
2/1000 = X/4,300,00

27. Do The Math p. 187 X = 8,600 people per year added to the population
Once we have the growth rate due to immigration, we can use the rule of 70 to figure out the doubling time
70/0.2% per year = 350 years

28. Demographic Transition
As a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population growth
Phase 1: Slow Population Growth
High birth rates and high death rates offset each other
Found in pre-industrial nations
Almost every nation on earth has moved past this point

29. Demographic Transition
Phase 2: Rapid Population Growth
Death rates decline while birth rates remain high
Due to better sanitation, healthcare and food
Occurs right after industrialization
Phase 3: Stable Population Growth
Death rates remain low while birth rates decline
Due to improved education and economic increases
Occurs as nations’ economies diversify

30. Demographic Transition
Phase 4: Declining Population Growth
Birth rates decline below death rates
Found in nations with extremely diverse economies and huge wealth
Age structure will have more elderly than young people
Immigration can counteract the drop in birth rates

33. Family Planning Can be promoted by a country to slow population growth
When education levels of women increase, TFR falls
Educated women:
Choose a later start for reproduction
Choose family planning (birth control)
As a result, have fewer children
Can be promoted by a country to slow population growth

34. Population Size and Economic Development
Are not equally distributed
Many developing countries have larger populations than developed countries
Developed nations also consume resources at a greater rate than their populations would indicate
This leads to larger ecological footprints in developed countries

37. Impact = Population x Affluence x Technology
IPAT Model
Impact = Population x Affluence x Technology
Summarizes the impact of human lifestyles
Population
More people = bigger impact
Affluence
More resource consumption = bigger impact
Technology
Can be beneficial
Alternative energy, non-polluting chemicals
Can be destructive
Causes pollution, uses natural resources

41. Local Resource Use Benefits Costs
Reduced transportation costs and pollution
Can stimulate economic activity
Costs
Resources in limited supply can be overused
Agricultural land, wood from forests, water

42. Global Resource Use Benefits Costs
Can distribute resources to a wider population that may desperately need them
Costs
Greater pollution from transportation and fossil fuel use

45. Urban Resource Use Benefits Costs
Individuals living near public transport, shopping and other services use fewer resources, require less infrastructure, and pollute less
Costs
Suburban sprawl creates more pollution, more resource use, and more infrastructure
Slums can spring up around poorly planned, rapidly growing urban areas

48. Affluence Nations’ wealth is measured in Gross Domestic Product (GDP)
Consumer spending
Investments
Government spending
Exports minus imports
Increases in GDP correlate to increases in pollution and consumption of natural resources
At a certain point, affluence can become a tool to make environmentally sound choices

49. Sustainability Two factors greatly affect population growth Education
The more educated a population is, the fewer children they have
Family Planning
Women choose to have fewer children when they are offered culturally accepted forms of birth control