Chapter 12 The Human Population: Growth, Demography, and Carrying Capacity

Transcription

1 Chapter 12 The Human Population: Growth, Demography, and Carrying Capacity

2 The History of the Human Population Years Elapsed Year Human Population 3,000,000 10,000 B.C.E. (Agricultural Revolution) 5-10 Million 10,000 1 A.D. 170 Million 1, (Industrial Revolution) 1 Billion Billion Billion Billion Billion Billion * 7 Billion * 8 Billion *projected; Source: U.S. Census Bureau

3 12-1 Factors Affecting Human Population Size Grow or decline through interaction of 4 factors: Births Deaths Migration fertility Population change = (births + immigration) (deaths + emigration)

4 To calculate, demographers use birth rate/crude birth rate= # of live births per 1,000 people in a pop. in a given year Death rate/crude death rate= # of deaths per 1,000 people in a pop. in a given year Rate of the world s annual population change (excludes migration) is expressed as a % Formula pg. 255

5 Where are people located? Populations of China and India comprise 37% of the world s population. The U.S. is the next most populated with 4.5% of the world s people

6 How does fertility affect population size? 2 types of fertility rates affect a country s size and growth rate: 1) Replacement-level fertility The # of children a couple must bear to replace themselves (2.1 in developed; 2.5 in developing) 2) Total fertility rate (TFR) An estimate of the average number of children a woman will have during her childbearing years 15-44

7 Population of the U.S. is currently 303 million A drop in TFR has slowed the growth, but it is still growing faster than any other developed country B/C of high per capita resource use and waste, growth in the U.S. has huge environmental impact Also we do not know how long we can continue w/o overshooting earth s carrying capacity for humans

8 Demographic transition Between 1910 and 1930, birth rates fell sharply due to 1) Country underwent industrialization and urbanization 2) More women got an education and began working outside the home Shift from high BR and DR to low during industrialization known as demographic transition

9 BR remained low in 1930 s because of Great Depression Began rising 1940 s during WWII After WWII sharp rise in birth rate ( ) is known as the baby-boom period 79 million people were added experienced echo boom in # of births as the large number of baby boomers began having children

10 Factors affecting BR and fertility 1) Importance of children as part of the work force 2) Urbanization 3) Cost of raising and educating children 4) Educational and employment opportunities for women 5) Infant mortality rate 6) Average age at marriage 7) Availability of public or private pension systems 8) Availability of legal abortions and birth control 9) Religious beliefs, traditions, and cultural norms

11 Factors affecting Death Rates More people started living longer b/c: 1) increased food supply 2) better nutrition 3) improvements in medical and heath technology 4) improved personal hygiene and sanitation 5) safer water supplies

12 Overall health of a country 2 indicators Life expectancy = avg. number of years a newborn can expect to live Infant mortality rate= # of babies out of every 1,000 born who die before their 1 st birthday B/C it reflects general nutrition and health care, infant mortality is the single most important measure of a society s quality of life

13 How does the U.S. measure up? U.S. infant mortality rate is higher than 40 other countries b/c 1) Inadequate health care for the poor women and their babies 2) Drug addiction among pregnant women 3) Has the highest teenage pregnancy rate of any industrialized country

14 What are age structure diagrams? Age structure: the proportion of the population at each age level Constructed by plotting the percentages or numbers of males and females in the total population in 3 categories: Pre-reproductive age (0-14) Reproductive age (15-44) Post-reproductive age (45+)

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16 How does age structure affect population growth? The major determining factor in a country s future population growth is the # of people under the age of 15 Ex: 44% of Nigeria s population is under age 15, the TFR is 5.8 children per woman. At this rate, current population of 130 million will reach 304 million in 2050.

17 Using age structures to make projections Changes in the distribution of a country s age groups have long lasting economic and social impacts Ex: Baby boom generation Dominates the population s demands for goods and services Influence elections and legislation Retirement of baby boomers may leave shortage of workers

18 How do we support baby boomers? The economic burden of supporting the baby boom generation will fall to the baby-bust generation (aka GenX) These are the 44 million born b/t 1965 and 1976 May have to pay higher income, healthcare and social security taxes

19 Baby-bust generation followed by echoboom generation (aka GenY and millenials) 83 million born b/t 1977 to 2000 Largest generation Will eventually have more economic power than their baby boom parents

20 Effects of population decline from reduced fertility Reduced fertility meaning the age structure will shift to a high percentage of people over 60 Gives population decline If gradual, the harmful effects can be managed If rapid, leads to the following problems: Sharp rise in costs for public services and health Fewer working taxpayers and labor shortages May be necessary to raise retirement age, taxes, cut benefits, increase legal immigration

21 Effects of Population Decline from a rise in death rates Deaths from diseases such as AIDS disrupt a country s social and economic structure Large # of people in a particular age group are removed from the country s future Life expectancy drops If AIDS, the deaths are usually the young who help run the country and everyday life for millions

22 Demographic transition hypothesis According to this hypothesis: First, death rates rise and then birth rate drops 4 Stages: 1) Preindustrial stage Little population growth b/c harsh living conditions lead to both a high birth rate and high death rate 2) Transitional stage Industrialization begins, food production rises and health care improves leading to a drop in death rates and birth rates remain high population growth

23 3) Industrial stage Birth rate drops as industrialization and modernization become widespread Population grows, but at a slower rate 4) Postindustrial stage Birth rate declines further, equaling the death rate and finally reaching zero population growth. Birth rate eventually falls below death rate and total population decreases slowly.

24 How can family planning help reduce birth and abortion rates? Family planning provides educational and clinical services that help couples choose how many children to have and when. Provide information on: 1) birth spacing 2) birth control 3) health care

25 Economic rewards and penalties to help reduce birth rates 20 countries offer small payments to people who agree to use contraceptives or to be sterilized. However, these incentives are most likely to attract those who already have all the children they want. Some countries penalized those who have more than 1 or 2 children by raising taxes, charging fees, and eliminating tax deductions for a couple s third child

26 Case Study 1: China Population growth controlled by a strongly enforced government program. Between 1972 and 2004, China s birth rate was cut in half. Couples with one child are rewarded with extra food, larger pensions, better housing, free school tuition, and preferential employment for their child

27 Cons China currently faces challenges in two areas: 1) large elderly population 2) larger male population

28 Case Study 2: India India has tried to control its population for years. The world s first national family planning program began here in Poverty, malnutrition, and environmental problems make this more difficult.

29 Efforts to limit population have not been successful because poor couples believe they need several children for work and care Because of strong cultural preference for male children, some couples keep having children until they produce one or more boys And even though 90% of Indian couple know about birth control, only 43% actually use it