Human PopulationHuman Population

Chapter 8Chapter 8

What you need to know:What you need to know:

The scope of human The scope of human population growthpopulation growth

The effect of population, The effect of population, affluence and technology affluence and technology on the environmenton the environment

Fundamentals of Fundamentals of demography demography

The demographic transitionThe demographic transition Factors that affect Factors that affect

population growthpopulation growth The HIV/AIDS epidemicThe HIV/AIDS epidemic

Case study: China’s one-child policyCase study: China’s one-child policy

In 1970, China’s 790 million In 1970, China’s 790 million people faced starvationpeople faced starvation

The government instituted a one-The government instituted a one-child policychild policy– China’s growth rate China’s growth rate

plummetedplummeted– In 1984, the policy exempted In 1984, the policy exempted

ethnic minorities and farmers ethnic minorities and farmers Unintended consequences: killing Unintended consequences: killing

female infants and a black-female infants and a black-market trade in teenage girlsmarket trade in teenage girls

Human population growth: 7 billionHuman population growth: 7 billion

Populations continue to rise in most countriesPopulations continue to rise in most countries– Particularly in poverty-stricken developing nationsParticularly in poverty-stricken developing nations

Although the rate of growth is slowing, we are still Although the rate of growth is slowing, we are still increasing in absolute numbersincreasing in absolute numbers

It would take 30 years, counting once each second, to count to a billion!

The human population is still growing rapidlyThe human population is still growing rapidly

It took all of human history to reach 1 billionIt took all of human history to reach 1 billion In 1930, 130 years later, we reached 2 billion, In 1930, 130 years later, we reached 2 billion,

and added the most recent billion in 12 yearsand added the most recent billion in 12 years

Due to exponential growth, even if the growth rate remains steady, population will continue to grow

Rule of 70Rule of 70

REVIEW!REVIEW! Divide the growth rate by 70 to get the Divide the growth rate by 70 to get the

years it will be until the population doublesyears it will be until the population doubles For example: growth rate is 1.8%For example: growth rate is 1.8% The years until population doubles is The years until population doubles is

70/1.8= ~39 years (or you can estimate-70/1.8= ~39 years (or you can estimate-70/2 = 35 and it will be a bit more.)70/2 = 35 and it will be a bit more.)

Rates of growth vary from region to regionRates of growth vary from region to region

At today’s 1.2% global growth rate, the At today’s 1.2% global growth rate, the population will double in 58 years (70/1.2 = 70)population will double in 58 years (70/1.2 = 70)

If China’s rate continued at 2.8%, it would have If China’s rate continued at 2.8%, it would have had 2 billion people in 2004.had 2 billion people in 2004.

Is population growth really a problem?Is population growth really a problem?

Population growth results from technology, Population growth results from technology, sanitation, foodsanitation, food– Death rates drop, but not birth ratesDeath rates drop, but not birth rates

Some people say growth is no problemSome people say growth is no problem– New resources will replace depleted New resources will replace depleted

onesones– But, some resources (i.e., biodiversity) But, some resources (i.e., biodiversity)

are irreplaceableare irreplaceable Quality of life will suffer with unchecked Quality of life will suffer with unchecked

growthgrowth– Less food, space, wealth per personLess food, space, wealth per person

Causes and consequences of population growthCauses and consequences of population growth

Some fear falling populationsSome fear falling populations

Population growth is correlated with Population growth is correlated with poverty, not wealthpoverty, not wealth

Policymakers believe growth increases Policymakers believe growth increases economic, political, military strengtheconomic, political, military strength– They offer incentives for more childrenThey offer incentives for more children– 67% of European nations think their 67% of European nations think their

birth rates are too lowbirth rates are too low– In non-European nations, 49% feel their In non-European nations, 49% feel their

birth rates are too highbirth rates are too high

Population growth affects the environmentPopulation growth affects the environment

The IPAT model: I = P x A x T x SThe IPAT model: I = P x A x T x S– Our total impact (I) on the environment results Our total impact (I) on the environment results

from the interaction of population (P), affluence from the interaction of population (P), affluence (A) and technology (T), with an added sensitivity (A) and technology (T), with an added sensitivity (S) factor(S) factor

– Population = individuals need space and resourcesPopulation = individuals need space and resources– Affluence = greater per capita resource useAffluence = greater per capita resource use– Technology = increased exploitation of resourcesTechnology = increased exploitation of resources– Sensitivity = how sensitive an area is to human Sensitivity = how sensitive an area is to human

pressurepressure– Further model refinements include education, Further model refinements include education,

laws, ethicslaws, ethics

Humanity uses 1/3 of all the Earth’s net primary production

Computer simulations predict the Computer simulations predict the futurefuture

Simulations project trends in Simulations project trends in population, food, pollution, population, food, pollution, and resource availabilityand resource availability

If the world does not change, If the world does not change, population and production population and production will suddenly decreasewill suddenly decrease

In a sustainable world, In a sustainable world, population levels off, population levels off, production and resources production and resources stabilize, and pollution stabilize, and pollution declinesdeclines

DemographyDemography

All population principles apply to humansAll population principles apply to humans– Environmental factors limit population growthEnvironmental factors limit population growth

Humans can raise the environment’s carrying Humans can raise the environment’s carrying capacity through technologycapacity through technology– How many humans can the world sustain? 1 How many humans can the world sustain? 1

– 33 billion– 33 billion– Population growth can’t continue forever Population growth can’t continue forever

DemographyDemography DemographyDemography = the = the

application of population application of population ecology to the study of ecology to the study of humanshumans– Demographers study Demographers study

population size, population size, – Density and Density and

distribution,distribution,– Age structure, sex Age structure, sex

ratio, ratio, – And birth, death, And birth, death,

immigration, and immigration, and emigration ratesemigration rates

Population size and densityPopulation size and density Nobody knows the Nobody knows the

ultimate human ultimate human population sizepopulation size

But numbers are not the But numbers are not the only important aspectonly important aspect

Highest population Highest population density is in temperate, density is in temperate, subtropical, and tropical subtropical, and tropical biomesbiomes– Some areas are heavily Some areas are heavily

impacted by impacted by urbanization, pollution, urbanization, pollution, and fossil fuel useand fossil fuel use

Population distributionPopulation distribution

Increased density impacts the environment, but Increased density impacts the environment, but relieves pressure in less-populated areasrelieves pressure in less-populated areas

Humans are unevenly distributed around the globeHumans are unevenly distributed around the globe– Unpopulated areas tend to be environmentally Unpopulated areas tend to be environmentally

sensitive (high S value in the IPAT equation)sensitive (high S value in the IPAT equation)

Age structure affects future population sizeAge structure affects future population size

Having many individuals Having many individuals in young age groups in young age groups results in high results in high reproduction and rapid reproduction and rapid population growthpopulation growth

Age pyramid of the U.S. in 2005

A changing age structure poses challengesA changing age structure poses challenges

Many populations are getting olderMany populations are getting older– Older people need care and financial assistanceOlder people need care and financial assistance– But, also reduces the number of dependent But, also reduces the number of dependent

children and crime rateschildren and crime rates

Sex ratiosSex ratios

Naturally occurring sex ratios for humans Naturally occurring sex ratios for humans slightly favors males (100 females born to slightly favors males (100 females born to 106 males)106 males)

In China, 120 boys were reported for 100 In China, 120 boys were reported for 100 girlsgirls– Cultural gender preferences, combined Cultural gender preferences, combined

with the government’s one-child policy, with the government’s one-child policy, led to selective abortion of female fetusesled to selective abortion of female fetuses

– Had the undesirable social consequences Had the undesirable social consequences of many single Chinese menof many single Chinese men

– Teenage girls were kidnapped and sold as Teenage girls were kidnapped and sold as bridesbrides

Population growth depends on various factorsPopulation growth depends on various factors

Whether a population grows, shrinks, or Whether a population grows, shrinks, or remains stable depends on:remains stable depends on:– Rates of birth, death, and migrationRates of birth, death, and migration– Birth and immigration add individualsBirth and immigration add individuals– Death and emigration remove individualsDeath and emigration remove individuals

Technological advances led to dramatic Technological advances led to dramatic decline in human death rates decline in human death rates – Widening the gap between birth rates Widening the gap between birth rates

and death rates resulting in population and death rates resulting in population expansionexpansion

Immigration and emigration play large rolesImmigration and emigration play large roles

Refugees flee their home country as a result of Refugees flee their home country as a result of war, civil strife, and environmental degradationwar, civil strife, and environmental degradation– 25 million escape poor environmental conditions25 million escape poor environmental conditions– Movement causes environmental problems with Movement causes environmental problems with

no incentives to conserve resourcesno incentives to conserve resources

Falling growth rates do not mean fewer peopleFalling growth rates do not mean fewer people

Falling rates of growth Falling rates of growth do not mean a do not mean a decreasing population, decreasing population, but only that rates of but only that rates of increase are slowingincrease are slowing

Factors affecting total fertility rateFactors affecting total fertility rate

Total fertility rate (TFR)Total fertility rate (TFR) = the average = the average number of children born per female number of children born per female

Replacement fertilityReplacement fertility = TFR that keeps = TFR that keeps the size of a population stablethe size of a population stable

Increasing urbanization decreases TFRIncreasing urbanization decreases TFR– Children go to school, and increase costs Children go to school, and increase costs

With social security, elderly parents need With social security, elderly parents need fewer children to support themfewer children to support them

Greater education allows women to enter Greater education allows women to enter the labor force, with less emphasis on child the labor force, with less emphasis on child rearingrearing

Life expectancy is increasingLife expectancy is increasing

Natural rate of population change Natural rate of population change = = due to birth and death rates alonedue to birth and death rates alone– In countries with good sanitation, health In countries with good sanitation, health

care, and food, people live longercare, and food, people live longer Life expectancyLife expectancy = average number of = average number of

years that an individual is likely to continue years that an individual is likely to continue to liveto live– Increased due to reduced rates of infant Increased due to reduced rates of infant

mortalitymortality– Urbanization, industrialization, and Urbanization, industrialization, and

personal wealthpersonal wealth

The demographic transitionThe demographic transition

Demographic transitionDemographic transition = a model of = a model of economic and cultural change to explain the economic and cultural change to explain the declining death and birth rates in declining death and birth rates in industrializing nations industrializing nations

Stable preindustrial state of high birth and Stable preindustrial state of high birth and death rates change to a stable post-death rates change to a stable post-industrial state of low birth and death ratesindustrial state of low birth and death rates

As mortality decreases, there is less need As mortality decreases, there is less need for large familiesfor large families– Parents invest in quality of lifeParents invest in quality of life

The demographic transition’s four stagesThe demographic transition’s four stages

Population growth is seen as a temporary phenomenonPopulation growth is seen as a temporary phenomenon

Is the demographic transition universal?Is the demographic transition universal?

It has occurred in Europe, U.S., Canada, It has occurred in Europe, U.S., Canada, Japan, and other nations over the past 200-Japan, and other nations over the past 200-300 years300 years

But, it may or may not apply to all But, it may or may not apply to all developing nationsdeveloping nations

The transition could fail in cultures The transition could fail in cultures – That place greater value on childbirth or That place greater value on childbirth or – Grant women fewer freedomsGrant women fewer freedoms

For people to attain the material standard of living of North Americans, we would need the natural resources of four and a half more Earths

Empowering women reduces growth ratesEmpowering women reduces growth rates

Fertility rates drop when women gain access to contraceptives, Fertility rates drop when women gain access to contraceptives, family planning programs and better educational opportunitiesfamily planning programs and better educational opportunities

In 2007, 54% of married women worldwide used contraception; In 2007, 54% of married women worldwide used contraception; – China = 86%; the U.S. = 68%; 20 African nations < 10%China = 86%; the U.S. = 68%; 20 African nations < 10%

Women with little power have unintended pregnancies

Family planning reduces unintended Family planning reduces unintended pregnanciespregnancies

Blue = family planning accessibleRed = family planning not accessible

Gender equityGender equity

Women lack the information and personal Women lack the information and personal freedom to achieve equal power with menfreedom to achieve equal power with men– 2/3 of people who cannot read, and 60% 2/3 of people who cannot read, and 60%

of those living in poverty are womenof those living in poverty are women

We are still a long way from achieving gender equality

Population policies and family planning workPopulation policies and family planning work

Many countries provide incentives, education, Many countries provide incentives, education, contraception, and reproductive health care contraception, and reproductive health care

Funding and policies that encourage family Funding and policies that encourage family planning lower population growth rates in all planning lower population growth rates in all nationsnations– Thailand has an educational based Thailand has an educational based

approach to family planning and its growth approach to family planning and its growth rate fell from 2.3% to 0.7%rate fell from 2.3% to 0.7%

– Brazil, Mexico, Iran, Cuba, and other Brazil, Mexico, Iran, Cuba, and other developing countries have active programsdeveloping countries have active programs

The International Conference on Population and The International Conference on Population and DevelopmentDevelopment

In 1994 Cairo, Egypt, 179 nations called on all In 1994 Cairo, Egypt, 179 nations called on all governments to offer universal access to governments to offer universal access to reproductive health care within 20 yearsreproductive health care within 20 years– Offer better education and health care and Offer better education and health care and

alleviate poverty, disease, and sexismalleviate poverty, disease, and sexism Despite the success of family planning, recent Despite the success of family planning, recent

Republican administrations in the U.S. have Republican administrations in the U.S. have declined to fund family-planning effortsdeclined to fund family-planning efforts– George W. Bush cancelled funding as one of George W. Bush cancelled funding as one of

his first acts on becoming U.S. president in his first acts on becoming U.S. president in 20012001

Poverty and population growth are correlatedPoverty and population growth are correlated

Poorer societies have higher growth rates than Poorer societies have higher growth rates than wealthier societieswealthier societies– Consistent with the demographic transition theoryConsistent with the demographic transition theory– They have higher fertility and growth rates, with They have higher fertility and growth rates, with

lower contraceptive uselower contraceptive use

99% of the next billion people added will be born in poor, less developed regions that are least able to support them

Poverty results in environmental degradationPoverty results in environmental degradation

Africa’s Sahel region and western China is Africa’s Sahel region and western China is turning to desertturning to desert

Wealth also produces severe environmental Wealth also produces severe environmental impactsimpacts

The population problem does not exist only The population problem does not exist only within poor countries within poor countries

Affluent societies have enormous resource Affluent societies have enormous resource consumption and waste productionconsumption and waste production– People use resources from other areas, as People use resources from other areas, as

well as from their ownwell as from their own– Individuals’ ecological footprints are hugeIndividuals’ ecological footprints are huge

One American has as much environmental impact as 6 Chinese or 12 Indians or Ethiopians

The Earth can’t support our consuming lifestyleThe Earth can’t support our consuming lifestyle

Humanity’s global ecological footprint surpassed Earth’s capacity to support us in 1987

The wealth gap and population growth cause The wealth gap and population growth cause conflictconflict

The stark contrast between affluent and poor societies The stark contrast between affluent and poor societies causes social and environmental stresscauses social and environmental stress

The richest 20% use 86% of the world’s resourcesThe richest 20% use 86% of the world’s resources– Leaves 14% of the resources for 80% of the world’s Leaves 14% of the resources for 80% of the world’s

people to sharepeople to share Tensions between “haves” and “have-not’s” are Tensions between “haves” and “have-not’s” are

increasingincreasing

HIV/AIDS impacts African populationsHIV/AIDS impacts African populations

Of 40 million in the world infected, 27 million Of 40 million in the world infected, 27 million live in sub-Saharan Africalive in sub-Saharan Africa

Low rates of contraceptive use spread the Low rates of contraceptive use spread the diseasedisease– 1 in 5 south Africans are infected 1 in 5 south Africans are infected

HIV is well established and spreading quickly around the world

Demographic changes have severe effectsDemographic changes have severe effects

6,000 Africans die each day6,000 Africans die each day– Increased infant mortality Increased infant mortality – Life expectancy fell from 59 to Life expectancy fell from 59 to

4040– Millions of orphans createdMillions of orphans created

Young, productive people dieYoung, productive people die– Communities break down Communities break down – Income and food production Income and food production

decline decline – Medical expenses and debt Medical expenses and debt

skyrocket.skyrocket.

AIDS undermines the transition of developing countries to modern technologies

Demographic fatigueDemographic fatigue Demographic fatigue = Demographic fatigue = governments face governments face

overwhelming challenges related to overwhelming challenges related to population growth. population growth. – With the added of stress of HIV/AIDS; With the added of stress of HIV/AIDS;

governments are stretched beyond their governments are stretched beyond their capabilitiescapabilities

– Problems grow worseProblems grow worse Nations in Africa must take aggressive steps Nations in Africa must take aggressive steps

soon soon – Or these countries will have rising death Or these countries will have rising death

rates and increased birth rates rates and increased birth rates – It would cause a profoundly negative It would cause a profoundly negative

outcome, both for humans and the outcome, both for humans and the environmentenvironment

ConclusionConclusion The human population is larger than at any time The human population is larger than at any time

in the pastin the past Populations are still rising, even with decreasing Populations are still rising, even with decreasing

growth rates growth rates Most developed nations have passed through the Most developed nations have passed through the

demographic transitiondemographic transition Expanding rights for women slows population Expanding rights for women slows population

growthgrowth Will the population stop rising through the Will the population stop rising through the

demographic transition, restrictive governmental demographic transition, restrictive governmental intervention, or disease and social conflict intervention, or disease and social conflict caused by overcrowding and competition?caused by overcrowding and competition?

Sustainability requires a stabilized population in Sustainability requires a stabilized population in time to avoid destroying natural systemstime to avoid destroying natural systems

QUESTION: ReviewQUESTION: Review

What has accounted for the majority of the What has accounted for the majority of the world’s population growth in recent years?world’s population growth in recent years?

a)a) Women are having more babiesWomen are having more babies

b)b) Death rates have dropped due to Death rates have dropped due to technology, medicine, and foodtechnology, medicine, and food

c)c) More women are using contraceptivesMore women are using contraceptives

d)d) Nothing, the population has dropped in Nothing, the population has dropped in recent yearsrecent years

QUESTION: ReviewQUESTION: Review

According to the I = P x A x T formula, what would happen According to the I = P x A x T formula, what would happen if China’s 1 billion people had a lifestyle like Americans?if China’s 1 billion people had a lifestyle like Americans?

a)a) Their population would automatically dropTheir population would automatically drop

b)b) Their population would automatically increaseTheir population would automatically increase

c)c) Their affluence and technology would increaseTheir affluence and technology would increase

d)d) Their impact on the environment would even outTheir impact on the environment would even out

QUESTION: ReviewQUESTION: Review

How have humans been able to raise the How have humans been able to raise the environment’s carrying capacity for our species?environment’s carrying capacity for our species?

a)a) Through technologyThrough technology

b)b) By eliminating limiting factorsBy eliminating limiting factors

c)c) Through increased consumptionThrough increased consumption

d)d) Spending more money on non-essential Spending more money on non-essential resourcesresources

QUESTION: ReviewQUESTION: Review

Areas that lack significant numbers of people, and Areas that lack significant numbers of people, and have a low population density are…have a low population density are…

a)a) No longer availableNo longer available

b)b) Best able to support higher densities of Best able to support higher densities of peoplepeople

c)c) Sensitive areas least able to support high Sensitive areas least able to support high densities of peopledensities of people

d)d) Located around tropical and grassland areasLocated around tropical and grassland areas

QUESTION: ReviewQUESTION: Review

Describe the relationship between growth rates Describe the relationship between growth rates and population size.and population size.

a)a) Falling growth rates automatically mean Falling growth rates automatically mean a smaller populationa smaller population

b)b) Falling growth rates automatically mean Falling growth rates automatically mean a larger populationa larger population

c)c) Falling growth rates means we no longer Falling growth rates means we no longer have a population problem have a population problem

d)d) Falling growth rates does not mean a Falling growth rates does not mean a smaller population, but that rates of smaller population, but that rates of increase are slowingincrease are slowing

QUESTION: Weighing the IssuesQUESTION: Weighing the Issues

In 2001 the Bush administration withheld funds for In 2001 the Bush administration withheld funds for international family planning. Should the U.S. international family planning. Should the U.S. fund family planning?fund family planning?

a)a) Yes, absolutelyYes, absolutely

b)b) Yes, but only in nations that follow U.S.-Yes, but only in nations that follow U.S.-approved programsapproved programs

c)c) Only if it can influence the nations’ policiesOnly if it can influence the nations’ policies

d)d) Never under any circumstances, it’s not Never under any circumstances, it’s not our jobour job

QUESTION: Weighing the IssuesQUESTION: Weighing the Issues

Would you rather live in a country with a larger Would you rather live in a country with a larger population or smaller population?population or smaller population?

a)a) Small population, so there will be more Small population, so there will be more resources for meresources for me

b)b) Small population, so there will be more Small population, so there will be more resources for others, including wildliferesources for others, including wildlife

c)c) Large population, so I can find a date Large population, so I can find a date

d)d) Large population, because people are our Large population, because people are our biggest resourcebiggest resource

QUESTION: Interpreting Graphs and DataQUESTION: Interpreting Graphs and Data

a)a) High birth and death rates rise cause population increasesHigh birth and death rates rise cause population increases

b)b) High birth and death rates, but population is stableHigh birth and death rates, but population is stable

c)c) High birth rates with low death rates cause population to High birth rates with low death rates cause population to increaseincrease

d)d) Low birth and death rates cause the population to decreaseLow birth and death rates cause the population to decrease

What happens during the “pre-industrial” stage of the demographic transition?

QUESTION: Interpreting Graphs and QUESTION: Interpreting Graphs and DataData

According to this age pyramid, Madagascar’s According to this age pyramid, Madagascar’s future population will be…?future population will be…?

a) Balancedb) Largerc) Much largerd) Smallere) Much smaller

QUESTION: Interpreting Graphs and QUESTION: Interpreting Graphs and DataData

According to these graphs, which countries had According to these graphs, which countries had access to family planning?access to family planning?

a) Iraq and Pakistanb) Malawi and Haitic) Malawi and Kenyad) Kenya and Bangladesh