1. Human Population
Chapter 8

3. Our World at Seven Billion
Human Population is Growing Rapidly:
Populations continuing to rise in most countries especially in poorest countries
Leading to stress on society, resources, and environment of poor nations
70 million new people added to world population each year
In 1800 world pop. reached 1 billion, in 1930 it reached 2 billion, the most last billion was added in 12 years
World growth rate is 1.2%, but is as high as 3% in some countries
At current growth rate world pop. will double in 53.8 year
49% of non-European nations feel their birth rates are too high

5. Some Countries Face Shrinking Populations:
66% of European governments think their birth rate is too low
Policymakers believe population growth increases economic, political, and military strength
Growth is correlated with poverty, not wealth
Strong, rich nations have low growth rates
Weak, poor nations have high growth rates
Some nations offer incentives for more children

6. Demography Studying Populations:
Demography - the application of population ecology to the study of change in human populations
There’s a carrying capacity for all species, including humans
How many humans can the world sustain?
1 billion to 33 billion: prosperity to abject poverty
Population growth can’t continue forever

7. Demographers study:
Population size
Density and distribution
Age structure
Sex ratio
Birth, death, immigration, and emigration rates
People are not distributed equally over the planet
Highest density: temperate, subtropical, tropical biomes and close to water
Cities are local high-density areas
Lowest density: away from water, extreme environments

9. Age Structure:
Describes relative numbers in each age class within a population
Diagrams (population pyramids) show age structure
Wide base denotes many young
High reproduction, rapid population growth
Even age distribution
Remains stable, births keep pace with deaths
Narrow base denotes fewer young than old
Population will likely decline over time

11. Age Structure: Sex Ratios: Many populations are getting older
Median global age is 28, will be 38 by 2050
Sex Ratios:
Unequal sex ratios can impact population growth
Human sex ratios at birth slightly favor males
For every 100 females born, 106 males are born
Some cultures have preference for male over female children
China’s one child policy led to selective abortion and abandonment of daughters

12. Population Changes:
Populations grow, shrink, or remain stable depending on rates of birth, death, and migration
Gap between birth and death rates have led to population expansion
Immigration/emigration have become more important
Overall global growth rate has declined in recent years
World population continues to grow

13. Influences on Population Growth:
Total fertility rate (TFR) – average number of children born to each female
Replacement fertility – TFR that keeps the size of a population stable (about 2.1)
Natural rate of population change – change due to birth and death rates alone (no migration)
Crude Birth Rates - # of births per 1,000 people per year
Crude Death Rates - # of deaths per 1,000 per year
Doubling time - # of years it takes for population to double “rule of 70”

14. Demographic Transition:
Life expectancy – average number of years that an individual is likely to live
Demographic transition – model of economic and cultural change
Pre-industrial stage – in pre-industrial societies, both birth and death rates are high
High birth rates compensate for high infant mortality
Population growth is slow
Transitional stage – declining death rates due to increased food production and medical care
Birth rates remain high since people are not used to low infant mortality rates
Population grows quickly

15. Industrial stage – birth rates fall as jobs provide opportunities for women outside the home and children are not needed in the workforce
Difference between birth and death rates shrinks
Population growth slows
Post-industrial stage – birth and death rates are low and stable
Population stabilizes or even shrinks

17. Population and Society:
Factors affecting fertility in a society
Access to family planning
Rates of infant mortality
Levels of women’s rights
Level of affluence
Importance of child labor
Government support for retirees
Family planning is key approach to population growth
Family planning gives women control over her reproductive window - time frame where a woman can become pregnant
A woman has potential to produce 25 children during her reproductive window

18. Empowering women reduces fertility rates
Increasing affluence lowers fertility
Poorer societies have higher population growth rates
In 1960, 70% of all people lived in developing nations
As of 2010, 82% live in these nations
99% of the next billion will be born in these nations

20. Expanding Wealth Can Increase Environmental Impact:
Affluent societies have enormous resource consumption and waste production
Ecological footprints are huge
Biocapacity - amount of biologically productive land and sea available to us