1. Chapter 9: The Human Population

2. Section 1: Studying Human Populations
Demography: study of populations, especially human populations.
Demographers study
-historical size and makeup of the populations
-Ecomomics
-Social structure

3. Two General Categories of Countries:
Developed Countries:
Higher average incomes
industrial economies
Slower population growth
Developing Countries:
Lower average incomes
agriculture-based economies
Rapid population growth

4. The Human Population Over Time
After growing slowly for thousands of years, the human population grew rapidly during the Modern Age (1800’s).
The exponential growth during this period was due to two factors—
a. increases in food production
b. improvements in hygiene
These factors came about because of the industrial and scientific revolutions.

6. Forecasting Population Size
Demographers use 4 properties to predict the changes that may occur in population sizes:
1. age structure
2. survivorship
3. fertility rate
4. migration
Prediction may be inaccurate, because human behavior changes suddenly and is hard to predict.

7. 1. Age Structure
Age structure : distribution of ages in a population at a particular time
Countries with high rates of growth = more young than old
Countries with slow/no growth = even distribution of ages

8. Age structure can be be graphed using a population pyramid. (pg. 236)

9. 2. Survivorship
Survivorship: % of members of a group that are likely to survive to a given age.
Demographers make predictions by studying a group of people born at the same time and notes when each dies.
Results may be plotted on a survivorship curve.

10. Types of Survivorship Curves:
Type I- most people live to be very old. (Germany and Japan)
Type II- death rate is similar at all ages.
Type III- pattern in poor human populations in which many children die.

11. 3. Fertility Rate:
Fertility Rate = # of babies born each year per 1000 women.
Demographers also calculate total fertility rate: the average number of children a women gives birth to in her lifetime.
Replacement level = avg # of children each parent must have in order to “replace” themselves = 2.1 (not all children born will survive and reproduce).
In 1972, the total fertility rate dropped below replacement level for the first time in the U.S.

12. 1990’s- total fertility rates remained below replacement level, but population continued to grow. Baby boomers grew up and had kids.

13. 4. Migration: Movement of individuals between areas
The population of developed countries might be decreasing if not for immigration.

14. Declining Death Rates
The dramatic increase in Earth’s human population in the last 200 years has happened because death rates have declined more rapidly than birth rates.
Death rates declined due to -
1. adequate food
2. clean water
3. safe sewage disposal
4. vaccines

15. Life Expectancy:
Life expectancy: average length of time that an individual is expected to live.
mostly affected by infant mortality
Expensive medical care is not needed to prevent infant deaths. Infant health is more affected by the parents’ access to education, food, fuel, and clean water.

16. Life expectancy worldwide has increased to > 67 years old
Life expectancy worldwide has increased to > 67 years old. But, new threats such as tuberculosis and AIDS are arising as populations become denser.
In developed countries, life expectancy may be 80 years or more.

17. The Demographic Transition
Demographic transition: models how economic and social changes affect population growth rates
Based on observations of histories of many developed countries
The theory behind the demographic transition is that industrial development causes economic and social progress that then affects population growth rates.

18. Stages of Demographic Transition
1st stage
society in preindustrial condition
high birth rate & death rate
population size is stable.
2nd stage
population explosion occurs
Death rates decline as hygiene, nutrition, and education improve
birth rates remain high, so population grows very fast.

19. 3rd stage
population growth slows (birth rate decreases)
birth rate becomes close to the death rate & the population size stabilizes
population is much larger than before the demographic transition.
4th stage
birth rate drops below replacement level
size of the population begins to decrease
*takes one to three generations for the demographic transition to occur in most developed countries.

20. Stages of the Transition
Which stage of the demographic transition is characterized
by a high birth rate and a declining death rate?

21. Women and Fertility
The factors most clearly related to a decline in birth rates are
1. increasing education: educated women find that they do not need to bear as many children to ensure that some will survive. They may also learn family planning techniques.
2. economic independence for women: women work to contribute to family’s prosperity & spend less energy bearing and caring for children. If parents must pay for child care, children may become a financial burden rather than an asset.

22. Today’s total fertility rates:
Developed countries: 1.6 children per woman
Developing countries: 3.1 children per woman

23. Section 2: Changing Population Trends
Populations that have high growth rates create environmental problems because they use resources at an increased rate and overwhelm the infrastructure.
Infrastructure includes the basic facilities and services that support a community. These services include:
1. public water supplies
2. sewer lines
3. power plants
4. roads and subways
5. schools
6. hospitals

24. Symptoms of an overwhelming population include:
1. surburban sprawl
2. overcrowded schools
3. polluted rivers
4. barren land
5. inadequate housing

25. Problems with Rapid Growth
A rapidly growing population can use resources faster than the environment can renew them.
ex. when wood is removed from forests faster than it can grow back
Wood would then be referred to as a “limited resource”.
Vegetation, water, and land are most critically affected by rapid growth.

26. A. Shortage of Fuelwood
In most poor countries, wood is the main fuel source.
When populations are stable, people use fallen tree limbs for fuel. When populations grow rapidly, deadwood does not accumulate fast enough to provide enough fuel.
Living trees are then cut which reduces the amount of wood available in each new year.
Collection of fuelwood has resulted in a loss of vegetation in parts of Africa, Asia, and India.

27. Fuel is used to boil water for sterilization & cook food
Without enough fuelwood, many people suffer from disease and malnutrition.

28. B. Unsafe Water
In places that lack infrastructure, the local water supply may be for drinking, washing, and sewage disposal.
water supply becomes a breeding ground for organisms that can cause diseases such as dysentery, typhoid, and cholera.
water systems of cities with populations doubling every 15 years cannot expand fast enough to keep up with growth

29. 2001:1 billion people worldwide lacked safe drinking water and 3 million died of diseases spread through water.
The Rio Grande River on the U.S.-Mexico border
Lima, Peru :half of population housed in shantytowns with no plumbing—cholera epidemic in 1991

30. C. Impacts on Land
shortage of arable land, land that may be used for farming.
Growing populations must make trade-offs between using land for agriculture, housing, or natural habitats.

31. 69 million people in Egypt depends on farming within Nile River valley, but this is where jobs are located, and where most Egyptians live.
less than 4 percent of Egypt’s land is arable; however ,they continue to build housing on what was once farmland.
Urbanization: people move to cities (mainly to find work); this causes suburban sprawl as people begin to live just outside the city in suburban areas

32. Problems associated with suburban sprawl: 1. traffic jams
2. inadequate infrastructure
3. the reduction of land for farms and wildlife habitat.
Housing in cities has become more costly, more dense, and in shorter supply.

33. A Demographically Diverse World
Not every country in the world is progressing through each stage of demographic transition.
Some countries now have modern industries, but incomes remain low. A few countries have achieved stable and educated populations with little industrialization.
Some countries seem to remain in the second stage and are unable to make enough educational and economic gains to reduce birth rates and move into the third stage.

34. focus is on least developed countries.
Least developed countries: identified by United Nations as showing fewest signs of development in terms of income, human resources, and economic diversity; also have high birth & death rates
These countries are given foreign aid and help with development programs to address their problems.

35. Populations are still growing rapidly in less developed countries, with most of the world’s population now within Asia.

36. Managing Development and Population Growth
Countries such as China, Thailand, and India have created campaigns to reduce the fertility rates of their citizens.
These campaigns include
1. public advertising,
2. family planning programs,
3. economic incentives,
4. or legal punishment.

37. In 1994, the United Nations held the International Conference on Population and Development (ICPD),
debates about the relationships between population, development, and the environment and goals were established

38. ICPD Goals for 2015
Provide universal access to safe and reliable family-planning methods.
Reduce infant mortality and mortality rates of children under five.
Lower maternal mortality rates in developing countries.
Increase life expectancy to more than 75 years.
Achieve universal access to primary education and ensure access for girls and women to secondary education

39. With these goals, worldwide fertility rates are dropping as shown below.

40. Growth is Slowing
Fertility rates have declined in both more-developed and less-developed regions.
predicted that worldwide population growth will be slower this century than the last century.
If current trends continue, most countries will have replacement level fertility rates by If so, world population growth would eventually stop.

41. Projections to 2050
Based on the graph below, most demographers predict the medium growth rate, and a world population of 9 billion in 2050.