7.1 Population Growth

• World population is 6.6 billion people (2007)• It is growing at a rate of 1.17 % per year, it will

double in 58 years.• Is this good or bad?• Human populations grew slowly until

relatively recently. P 134 fig 7.3, table 7.1• After 1600 AD populations began to increase

rapidly. Why?

Question

• The number of humans tripled in the 20th century, will it do so again in the 21st century?

• If it does, will we overshoot the carrying capacity of our environment and experience a catastrophic dieback?

7.2 Perspectives on Population Growth

• Does environment or culture control human populations? P135 fig 7.4

• Malthus – population increases at an exponential rate, while food supply grows slowly, leading to poverty, crime, war.

• Marx – population growth results from poverty.

Solutions

• Malthus – birth control• Marx – improved social conditions and

educational levels.• Gandhi – “There is enough for everyone’s

need, but not enough for anyone’s greed”.

Technology can increase carrying capacity

• In the past 200 years, food supplies have increased faster than population growth.

• Much of our growth has been based on easily acquired natural resources (fossil fuels).

• I=PATI=environmental impacts P=population size A=affluence T=technology

Population growth could bring benefits

• More people = larger markets, more workers, and efficiencies of scale in mass production

• More human ingenuity and intelligence.

Questions

• What larger worldview are reflected in this population debate?

• What positions do you believe neo-Malthusians and neo-Marxists might take on questions of human rights, resource abundance, or human perfectibility?

• Where do you stand on these issues?

Many Factors Determine Population Growth

• How many of us are there?• Demography: vital statistics about people: births,

marriages, deaths• There are two demographic worlds: one is old, rich,

and stable. The other is young, poor, and rapidly growing. P137 table 7.2 fig 7.5

• AIDS is a major limiting factor in Africa’s population. P137 Fig 7.6

• What do you notice about human population density on fig 7.7 p138

Fertility measures the number of children born to each woman

• Crude birth rate: The number of births in a year per thousand persons p138 table 7.3

• Total fertility rate: The number of children born to an average woman.

• Zero population growth: Births plus immigration in a population equals deaths plus emigration.

• Total fertility rates have been falling across the world. Fig 7.8 p139

Mortality is the other half of the population equation

• Crude death rates: The number of deaths per thousand persons in a year.

• Natural Increase: Crude death rates minus crude birth rates.

• Total Growth Rate: Determined from births, deaths, immigration, and emigration.

Life span and life expectancy describe our potential longevity

• Life expectancy: The average age that a newborn infant can expect to attain in any given society. P141 table 7.4

• Declining mortality, not rising fertility, is the primary cause of most population growth.

• There is a good correlation between annual income and life expectancy. P142 fig 7.1

• Where is the longest life expectancy?

Living longer has demographic implications

• Dependency ratio: The number of nonworking compared to working individuals in a population. P142 fig 7.11 7.12

• Emigration and immigration are important demographic factors

• More-developed regions are expected to gain about 2 million immigrants per year

• “Guest workers” often perform heavy, dangerous, or disagreeable work.

7.4 Ideal Family Size Is Culturally and Economically Dependent

• Many factors increase our desire for children• Pronatalist pressures: Factor’s that increase

people’s desires to have babies.• In developing countries, children are a source of

current and future income. Fig 7.13 p144• Society has a need to replace members who die

or become incapacitated.• Male pride is linked to having as many children

as possible.

Other factors discourage reproduction

• In highly developed countries, many pressures tend to reduce fertility.

• In less-developed countries, adding one more child to a family doesn’t cost that much.

• P144 fig 7.14 shows how U.S. birth rate over time.

• What caused the rise and fall of U.S. birth rate?

Could we have a birth dearth?

• Most European countries have birth rates below replacement rates (Italy, Russia, Austria, Germany, Greece, Spain, Japan, Singapore, Taiwan).

• This birth dearth might seriously erode the powers of Western democracies. However, a reduction in high resource using Western populations would spare the environment.

• Sperm production has fallen in industrialized countries due to toxins in the environment.

Questions

• How many children do you want to have?• Is this number different from that of your

parents or grandparents? Why or why not?

7.5 A Demographic Transition Can Lead To Stable Population Size

• Economic and social development influence birth and death rates

• Demographic transition: A pattern of falling death rates and birthrates in response to improved living conditions.

• P146 fig 7.15 stage 1 – food shortages, lack of sanitation and medicine

• Stage 2 – better jobs, medical care, sanitation• Stage 3 – More resources are concentrated on fewer

children• Stage 4 – Population is at a new equilibrium

There are reasons to be optimistic about population

• Demographic transition requires: • 1) improved standard of living • 2) increased confidence that children will survive

to maturity • 3) improved social status of women • 4) increased availability and use of birth control• Why are these 4 things essential?• Other factors: already developed technology,

learning from the mistakes of countries, modern communication

Many people remain pessimistic about population growth

• Many of the poorer countries appear to be stuck in stage 2-3, while population increases

• This puts a huge strain on available resources• Solution is birth control education

Social justice is an important consideration

• Social justice: Equitable access to resources and the benefits derived from them; a system that recognizes inalienable rights and adheres to what is fair, honest, and moral.

• The world has enough resources for everyone fig 7.16 p14

• Many of the rich countries acquired their wealth form being colonial powers

• What about the rights of other species?

Women’s rights affect fertility

• As women’s education and job opportunities increase, their fertility decreases p 148 fig 7.17

• Child survival is also crucial in stabilizing population

• Increased family income does not ensure better welfare for children. Mother’s rights improves child survival. Why?

7.6 Family Planning Gives Us Choices

• Fertility control has existed throughout history• Methods include: abstinence, folk medicine,

abortion, infanticice• Family Planning: Planning the timing of birth and

having as many babies as are wanted and can be supported

• Birth Control: Any method used to reduce births. Ex: delayed marriage, abstinence, contraception

Today there are many options

• 1) avoidance of sex during fertile periods• 2) mechanical barriers (condoms)• 3) surgical methods• 4) hormone-like chemicals that prevent

maturation• 5) physical barriers• 6) abortionTable 7.5 p149 shows the effectiveness of

different birth control methods

7.7 What Kind of Future Are We Creating

• Religion and politics complicate family planning• Many Muslim countries encourage large families• China’s 1 child policy has led to many forced

abortions. • P150 fig 7.19 shows countries that need family

planning• P150 fig 7.20 shows countries that want large

families

• Successful family planning requires:• 1) improved social, educational, and economic

status for women• 2) improved status for children• 3) acceptance of responsibility and choice in

fertility• 4) social security and political stability• 5) knowledge and availability of birth control