printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” Why ItMatters CASESTUDY 218 resources in Spanish. worksheets, multimedia,and resources, includinglabs, Go onlinetoaccessadditional Challenges onpage228. study Thailand’s Population population issuesinthecase Thailand isdoingtosolvetheir moreLearn aboutwhat in theworld? China affect peopleelsewhere How dopopulationissuesin consumption. contained waterunfitforhuman the sevenmajorriversinChina five-year period,54percent of in airpollution.Duringthesame resulted inacorresponding rise use from 2000–2005.This 70 percent increase inenergy largest populations,hada China, withoneoftheworld’s Changing PopulationTrends Section 2 Studying HumanPopulations Section 1 Chapter 9 HMDScience.com EN Online Vir onmental Science Population The Human

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Section 1 Studying Human Objectives Describe how the size and growth rate of the human Populations population has changed in the last 200 years.

The human population of Earth grew faster in the 20th century than it ever has Define four properties that before. This rapid growth has led to environmental problems around the globe. scientists use to predict We therefore must try to understand and predict changes in human populations. population sizes.

Demography is the study of populations. For human populations, Make predictions about demographers study the processes that influence the populations of countries to population trends based on age make comparisons and predictions. These include human behavior, economics, and social structure. Countries have been grouped by demographers into two general structure. categories, which define the ends of a continuum in patterns of development. Describe the four stages of the Developed countries have higher average incomes, slower population growth, and diverse industrial economies. Developing countries have lower average incomes, demographic transition. simple agriculture-based economies, and rapid population growth. Explain why different countries may be at different stages of The Human Population Over Time the demographic transition. After growing slowly for thousands of years, the industrial and scientific revolutions in the 1800s brought a period of exponential growth, meaning Key Terms that population growth rates increased during each decade (Figure 1.1). demography This growth was mostly due to increases in food production and im- age structure provements in hygiene. However, it is unlikely that Earth can sustain this survivorship growth for much longer. Some scientists believe that we cannot indefi- nitely sustain the current world population at today’s standards of living. fertility rate migration life expectancy Figure 1.1 demographic transition Exponential Growth Curve After growing slowly for thousands of years, the human population began to grow rapidly in the 1800s.

World Population Over Time Bronze and Middle Modern Neolithic Iron Ages Ages Age 8 2025 Stone Ages [<3500 BCE] (projected) 7 Bronze & Iron Ages [3500 BC – 500 AD] 2011 Middle Ages [500 AD – 1500 AD] 6 Modern Age [1500 AD – present (2011)] 1999 Future [2011+] 5 Year population reaches another billion 1987 4 1974 3 Black Death Domestication 1960 of plants and First large Roman Population (in billions) 2 animals empire(s) Empire 1930 1 1850 0 10,000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 1000 2000 Year BCE CE

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Figure 1.2

Age-Structure Diagrams These graphs allow demographers to compare the distribution of ages and sexes in a population. Each graph shows a typical shape for a population with a particular rate of growth.

Rapid Growth— Slow Growth— Zero or Declining Growth— Least Developed Nations Transitional Nations Most Developed Nations 80+ 75–79 Males 70–74 Females 65–69 60–64 55–59 Reproductive 50–54 years

Age 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 10 8 6 4 2 0 2 4 6 8 10 10 8 6 4 2 0 2 4 6 8 10 10 8 6 4 2 0 2 4 6 8 10 Percent of population Percent of population Percent of population

Forecasting Population Size How will your community change in the next 20 years? Will it need more schools or more retirement centers? Will more people move in and create demand for more roads and utility services? Demographers look at many properties of populations to predict such changes.

Age Structure Demographers can make many predictions based on age structure—the Figure 1.3 distribution of ages in a specific population at a certain time. For example, if a population has more young people than older people, the population Survivorship Curve Human size will likely increase as the young people grow up and have children. populations in general tend to show Type I survivorship curves, although Age structure can be graphed in a population pyramid, a type of double- they may vary in infant mortality sided bar graph. Figure 1.2 shows typical age structures for countries that or the advanced age at which have different rates of growth. Countries that have high rates of growth survivorship drops rapidly. usually have more young people than older people. Countries that have slow growth or no growth usually have an even distribution of ages. Typical Survivorship Curves 100

Type I Survivorship 80 Survivorship is the percentage of members of a group that are likely to survive to any given age. To predict survivorship, a demographer studies a 60 Type II group of people born at the same time and notes when each person dies. The results plotted on a graph might look like one of the types of survivor- 40 ship curves in Figure 1.3. A Type I survivorship curve shows a population

Percent of population surviving where most individuals live to an advanced age. Type II curves show pop- 20 Type III ulations where all ages have a similar death rate. Populations that have a Type III curve are those in which many offspring die. Human popula- 0 tions in developed countries show Type I curves, but populations living Time in extreme poverty may show Type III curves. In nonhuman populations, some animals in zoos show Type I curves, songbirds show Type II curves, and insects and fish show Type III curves. 220 Unit 3: Populations Connect to MATH

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Figure 1.4 Connect to MATH Fertility Rate The total fertility rate in the United States went through many changes from 1900 to 2000. The baby boom was a period of high fertility rates, and the Extending the Equation baby bust was a period of decreasing fertility. for Population Change Baby boom Baby bust The following equation is a simple way 4.0 to calculate the change in a population over a period of time: 3.5 change in

e = (births − deaths) t

a population r y t

i 3.0 l

i However, this equation does not t r e f

Replacement

l account for changes due to migration. a

t 2.5 level o Rewrite the equation to include T immigration and emigration. 2.0 Next, create an example word problem that would require the use 1.5 1920 1930 1940 1950 1960 1970 1980 1990 2000 of this new equation. Trade problems Year with a classmate, and try to solve the classmate’s new word problem. Source: National Center for Health Statistics.

Fertility Rates The number of babies born each year per 1,000 women in a population is Check for Understanding called the fertility rate. Demographers also calculate the total fertility rate, Predict How can a population pyramid or the average number of children a woman gives birth to in her lifetime. help demographers predict changes in a population over time? A graph of historical total fertility rates for the United States is shown in Figure 1.4. In 1972, the total fertility rate dropped below replacement level for the first time in U.S. history. Replacement level is the average number of children each parent must have in order to “replace” them- selves in the population. This number is about 2.1, or slightly more than 2, because not all children born will survive and reproduce. Total fertility rates in the United States remained below replacement level for most of the 1990s. However, due to births and immigration, the population continued to grow (Figure 1.5.) Total fertility in the U.S. since Figure 1.5 2000 has increased to around 2.06. U.S. Population Growth The population of the United States has continued to grow in the last half-century because of births as well as immigration. Migration Net U.S. Population Increases The movement of individuals from 35 Increase due to immigration one area to another is migration. 30 Increase due to births Movement into an area is immigra- 25 tion and movement out of an area 20 is emigration. Migration between 15 and within countries is a significant 10 part of population change. If not Number added to population (in millions) 5 for immigration, the populations of 0 many developed countries might be 1950–1960 1960–1970 1970–1980 1980–1990 1990–2000 decreasing. Decade

Source: U.S. Census Bureau.

Chapter 9: The Human Population 221 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” 222 Figure 1.7 Figure 1.6 Increasing LifeExpectancy nutrition haveincreasedlifeexpectancyinmanypartsoftheworld. lines­ developed countries(blueandpurple although itremainslowerinless increased worldwide(redline), 1900, Age Average LifeExpectancy 10 20 30 40 50 60 70 80 90 0 1955 ). Source: UNPopulationDivision. averagelifeexpectancyhas Least developedregions More developedregions Populations Unit 3: Average LifeExpectancy World Less developedregions 1975 by Region Year 1995 (projected)

Since

2015 Preventive medicine, Declining DeathRates decades asaresult epidemic. oftheAIDS in many countries southAfrican has expectancy decreasedLife inrecent are agrowing where concernin aworld can such spread diseases quickly. come more dense. Contagious such andtuberculosis asAIDS diseases areneeds met, most children have will chance agood ofsurviving. parents’ access to education, fuel,andclean water. food, basic Ifthese of 221countries Infant forinfant mortality. more health isaffected by the thehighest averagewith theU.S. incomeintheworld, ranks only 48out deaths. The rate infant mortality differs greatly among countries. In fact, countries,is80yearsdeveloped ormore. lifeexpectancy increased to more than 67years worldwide. For inanumber people of 1900. The graph in By 2000,therate was ofinfant less than mortality one-third oftherate in about 30years worldwide, rate andtheinfant high. mortality was very the death rate ofinfants less than was ayear old.In 1900,lifeexpectancy their The average number ofyears members ofapopulation are likely to live is Life Expectancy in theimages shownin rates, among especially infants andchildren. Thesefactors are illustrated contributed to declining also death ofvaccines covery inthe18th century access to adequate clean water, food, andsafe sewage disposal. The dis rates. Death rates have mainly declined because more now people have has happened because death rates have more declined rapidly than birth The dramatic increase inEarth’s human population inthe last 200years Meanwhile, aspopulations newthreats- be arise to lifeexpectancy medical careExpensive helpfulinpreventing isnotnecessarily infant sanitation, life expectancy. andbetter Figure 1.7 Life expectancy is most affected by ismost, affected infant mortality expectancy Life Figure 1.6 illustrates that average has lifeexpectancy . -

(c) ©Tetra Images/Getty Images; (tr) ©Paul Harris/Stone/Getty Images; (tl) ©Marcel & Eva Malherbe/The Image Works ECOFACT

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The Demographic Transition ECOFACT Populations in most developed countries are growing at fairly low rates. The Population Clock How can populations quadruple in one century, then stop growing or The Earth’s human population is shrink in the next century? The demographic transition is a model that de- increasing by 2.4 people each second, scribes how economic and social changes affect population growth rates. which accounts for births and deaths. This means Earth gains over 200,000 The model is based on observations of the histories of developed coun- people per day, or over 75 million tries. The graph in Figure 1.8 compares trends in birth rates, death rates, per year. and population sizes during the four stages of the transition.

Stages of the Transition In the first stage of the demographic transition, a society is in a preindus- Check for Understanding trial condition. The birth rate and the death rate are both at high levels Interpret Which stage of the and the population size is stable. Most of the world was in this condition demographic transition is characterized until about 1700, when the scientific and industrial revolutions began. by a high birth rate and a declining death In the second stage, death rates decline as hygiene, nutrition, and rate? education improve. But birth rates remain high, so the population grows very fast. In this stage, the population can double in less than 30 years. In the third stage of the demographic transition, population growth slows because the birth rate decreases. As the birth rates and death rates grow closer, the population size stabilizes at a point that is higher than before the demographic transition. In most countries that have passed through the transition, the population quadrupled during the 1900s. In the fourth stage, the birth rate drops below replacement level, so the size of the population begins to decrease. It has taken from one to three generations for the demographic transition to occur in most developed countries. Recent studies suggest that more stages may occur where birth rates rebound.

Figure 1.8 Demographic Transition The four stages of the demographic transition are shown here from left to right. Note the changes in population size with changing birth and death rates. Do you think that all countries will fit this pattern?

critical thinking Predict Do you think that all countries will fit this pattern?

Stage 1 Stage 2 Stage 3 Stage 4 Preindustrial Transitional Industrial Postindustrial High Large

Population size

Birth rate

Replacement level birth rate Population size Birth rate and death

Death rate Low Small Low Increasing Very high Decreasing Low Zero Negative growth rate growth rate growth rate growth rate growth rate growth rate growth rate

Time Chapter 9: The Human Population 223 Connect to BIOLOGY

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Connect to BIOLOGY Women and Fertility Female Influence The factors most clearly related to a decline in birth rates are increasing Females have the primary influence education and economic independence for women. In the demographic over reproductive rates in most species transition model, the lower death rate of the second stage is usually the of animals, because they invest more result of increased levels of education. Educated women find that they do energy in reproduction than males do. not need to bear as many children to ensure that some will survive. Also, Females usually produce and lay eggs the women may learn family planning techniques. They are able to con- or carry the fetus and give birth, and tribute to their family’s increasing prosperity by working, while spending care for the offspring. The time and less energy bearing and caring for children. Some countries that want to resources a female invests in each reduce birth rates have placed a priority on the education of females, as successful offspring is usually greater shown in Figure 1.9. than the energy a male must invest. Large families are valuable in communities in which children work or take care of older family members. But as countries modernize, parents are more likely to work away from home. If parents must pay for child care, children may become a financial burden rather than an asset. The elderly will not need the support of their children if pensions are avail- able. All of these reasons contribute to lower birth rates. Today, the total fertility rate in developed countries is about 1.85 children per woman, while in developing countries, the rate is about 4.2 children per woman.

Figure 1.9 Educating Women These women in Bolivia are learning to read. Many countries include the education of women in development efforts.

critical thinking Explain why some countries might be reluctant to educate women, even though it might improve the overall quality of living for a country. ©Sean Sprague/The Image Works ©Sean Sprague/The Image

Section 1 Formative Assessment

Reviewing Main Ideas Critical Thinking 1. Describe how the size and growth rate of 5. Analyzing Relationships Read the description the human population has changed in the last of life expectancy in this section. Explain why 200 years. the oldest people in a population may be much 2. Define four properties that scientists use to older than the average life expectancy. predict population sizes. 6. Evaluating Theories Do you think that 3. Explain what we can predict about a all countries will follow the pattern of the population’s likely growth rates based on its demographic transition? Explain your answer. current age structure. 4. Describe the four stages of the demographic transition.

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Section 2 Changing Population Objectives Describe three problems caused by rapid human population Trends growth. Compare population growth Some countries have followed the model of the demographic transition—they have problems in more-developed reached large and stable population sizes and have increased life expectancies. countries and less-developed But in many parts of the world, populations continue to have high rates of countries. growth, which creates environmental problems. A rapidly growing population uses resources at an increased rate and can overwhelm the infrastructure of a community. Analyze strategies countries Infrastructure is the basic facilities and services that support a community, such may use to reduce their as public water supplies, sewer lines, power plants, roads, schools, and hospitals. population growth. The symptoms of overwhelming popu­la­tion growth include suburban sprawl, overcrowded schools, polluted rivers, barren land, and inadequate housing, as Describe worldwide population shown in Figure 2.1. projections into the next century.

Problems of Rapid Growth Key Terms People cannot live without sources of clean water, fuel, and land that can infrastructure be used to acquire to produce food. A rapidly growing population can use EarableCOF landACT resources faster than the environment can renew them, unless resources urbanization come from elsewhere. Standards of living decline in an area when wood least developed countries is removed from local forests faster than it can grow back, or when wastes overwhelm local water sources. Vegetation, water, and land are the re- sources most critically affected by rapid population growth.

Figure 2.1

Resource Depletion Rapid population growth can put pressure on water sources, land, and materials used for fuel or shelter. The makeshift housing shown here is one consequence of unmanaged growth.

ECOFACT Land Area per Person If each person alive on Earth in the year 2000 was given an equal portion of existing surface land, each person would get about 0.025 km2 (7.3 acres, or about four football fields), In the year 2050, each person might get 0.017 km2 of land (4.2 acres, or about three football fields). ©Adrian Murrell/Stone/Getty Images

Chapter 9: The Human Population 225 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” 226 productivity. soil erosionandloweragricultural burn cropresidue. This canleadto to useforfuel, peoplemayhaveto countries. Ifthereisnotenoughwood inmanydeveloping of dailysurvival Fuelwood Figure 2.3 Figure 2.2 Unsafe Water drinking, bathing, washing, andsewagedisposal. treatment systems, peoplemayusethesamewatersupplyfor on theU.S.-Mexicoborder. Inareasthathavenosewageorwater Populations Unit 3:

Gathering fuelispart

This womaniswashingclothesintheRioGrande Women inMyanmar gathering firewood are shownin A ShortageofFuelwood can be sterilized bycan sterilized be boiling it, to doso. but fuelisneeded Also, is food plies parasites because itcarries is notsafe to drink ordiseases. The water many parts of the world, water taken directly from wells or public sup collecting fuelwood. Parts ofAfrica, Asia, andIndia have cleared been ofvegetation by people fast enough to provide enough fuel.People to cut downliving begin trees. trees. populations When grow rapidly, notaccumulate does deadwood are low, can fallentree people use limbs notharmthe forfuel,which does of thepoorest countries, isthemain fuelsource. wood populations When A supply offuelensures that can water aperson boil In food. andcook unsafe water source by used many people. Grande, shown in of diseases that were spread through water. The Rio safe water drinking andmore than 3milliondied In 2001,over lacked worldwide 1billionpeople fastpanded enoughthisgrowth. to keep upwith 15years,every andwater systems cannot ex be and cholera. isms that typhoid, cause such asdysentery, diseases water abreeding supply becomes ground fororgan- ing butforsewage disposal. also Asaresult, the supply may and wash notonly fordrinking - used be In places that lack infrastructure, thelocal water Unsafe Water disease andmalnutrition.disease Without many enough suffer fuelwood, from people often unsafe orharder to digest unless itiscooked. Many citieshave populations that are doubling Figure 2.3 , isoneexample ofan Figure 2.2 . In many - -

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(l) ©Kevin Fleming/Corbis; (br) ©Johnson Space Center/NASA Figure 2.4 Urbanization narrow NileRivervalley. sprawl (left)createsmanyproblems. MostofEgypt’s populationiscrowdedintothe era epidemic that had occurred in the Western Hemisphere in 75 years. water sources in 1991. In that year, Lima’s population sufferedno the plumbing. first chol The bacteria that cause cholera thrived in Lima’s unmanagedhalf of the population of Lima is housed in slums or shantytowns that have within cities becomes more citiesbecomes within costly, more dense, supply. andinshorter habitat.the reduction andwildlife ofland forfarms Meanwhile, housing This sprawl suburban leads to traffic jams, inadequate infrastructure, and workpeople inthecitiesbut move into suburban areas around thecities. ment from ofpeople rural areas to cities. In theUnited States, many populations may have of ashortage People prefer to live where have they easy access to resources. Growing Impacts onLand on farming within theNile within on farming Rivervalley, shownin 1.92 percent year. per For products, andexportable food Egyptdepends For example, Egypt’s population ofapproximately 83millionisgrowing at competing forland such uses asagriculture, housing, ornatural habitats. to growused crops. Growing populations make also trade-offs between amount ofland Egypt has available foragricultural purposes. continue to build housing onwhat which reduces was oncefarmland, the ever, theNile where Rivervalley is also most Egyptians live. Egyptians andless than isdesert, 4percentcountry ofEgypt’s land isarable. How- Lima, Peru, is another example of an area with unsafe water. More than Much oftheworld’s population isundergoing

A largeproportionoftheUnitedStatesisarableland, butsuburban arable land , which island that can be Figure 2.4 urbanization . Most ofthe , themove- The HumanPopulation Chapter 9: - Nile Rivervalley Population Issues. Go to Btofindthefieldstudy Appendix affected arablelandinEgypt? growth population hasrapid Infer How Che

FieldStudy c k f o r Understanding 227 Connect to HISTORY

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Connect to LAW A Demographically Diverse World International Development As you have seen, demographers may categorize countries as either The United Nations (UN) has an developed or developing. However, some demographers may prefer the important role in understanding and terms more developed and less developed to describe countries or regions, assisting the development of nations. because the reality of development is complex and politically sensitive. The UN holds conferences, publishes research, creates treaties, manages Not every country in the world is progressing through each stage of the international programs, and dispenses demographic transition according to the model. Some countries now have funds. modern industries, but incomes remain low. A few countries have achieved The UN also creates formal stable and educated populations with very little industrialization. Some designations, such as least developed countries seem to remain in the second stage of the model. These countries countries. Demographers, foreign aid have rapid population growth but are unable to make enough educational programs, and international treaties and economic gains to reduce the birth rate and move into the third stage. may use these designations. In recent years, the global community has begun to focus on the least developed countries. These countries show few signs of development and in some cases have increasing death rates while birth rates remain high. Least developed countries are officially identified by the United Nations, using three criteria: low income weak human assets, and economic vulnerability. The low income criterion is based on a three-year average of gross national income per person of less than $750. Human assets that are considered include nutrition, health, education, and adult literacy.

CASESTUDY Thailand’s Population Challenges Population growth is a major concern for many developing countries. But the options are limited for a country that has a poor economy and growing demands for limited resources. Thailand is one country that has effectively and purposefully slowed its population growth. Around 1970, Thailand’s population was growing at a rate of more than 3 percent per year, and the average Thai family had 6.3 children. The country had increasing environmental problems, including air pollution in major cities and unsafe water supplies. Thailand’s emissions of carbon dioxide from burning fossil fuels almost doubled between 1990 and 1997. In Thailand’s capital, Bangkok, one-ninth of residents have respiratory problems, and many people die of waterborne diseases each year. Bangkok, Thailand is one of the In 1971, Thailand’s government adopted a policy to reduce most crowded and polluted cities Thailand’s population growth. The policy included increased in the world. However, population education for women, greater access to health care and growth is slowing in Thailand, and some environmental problems are starting to be solved. ©Jodi Cobb/Getty Images

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Figure 2.5 The third criterion, economic vulnerability, is based on such indicators as the instability Growth Rates Growth rates vary in different parts of the world. of agricultural production and the export of critical thinking goods and services. Some of these least devel- Identify Which regions will contribute the most growth? oped countries that have been identified by the United Nations include Haiti, Madagascar, World Population Growth by Region Malawi, Somalia, Samoa, Afghanistan, Ban- 9,000 8,000 gladesh, and the Sudan. These countries may Asia be given priority for foreign aid and develop- 7,000 Africa ment programs to address both their popula- Latin America 6,000 tion problems and environmental issues. Europe 5,000 Northern America Growth rates for different parts of the (U.S., Canada, world are shown in Figure 2.5. Populations are 4,000 Greenland) relatively stable in Europe, the United States, 3,000 Canada, Russia, South Korea, Thailand, 2,000 China, Japan, Australia, and New Zealand. In World population (in millions) 1,000 contrast, populations are still growing rapidly in less developed regions. Most of the world’s 0 1750 1800 1850 1900 1950 1999 2050 population is now within Asia. Year (projected)

CASESTUDY Thailand’s Population Strategies improved health care for mothers and children openness of the people, government, and community leaders to changing social traditions cooperation of private and nonprofit organizations with the government increases in women’s rights and ability to earn income economic incentives such as building loans for families who participated in family planning programs creative family planning programs promoted by popular government leaders high literacy rates of women (80 percent in 1980Critical and 94 Thinkingpercent in 2000)

contraceptives, and economic incentives to parents who Critical Thinking have fewer children. Fifteen years later, the country’s population growth rate had been cut to about 1.6 percent. 1. Applying Ideas For what reasons could By 2012, the growth rate had fallen to 0.54 percent and the Thailand be described as a developing country average Thai family had 1.7 children. The infant mortality in the 1970s? In what ways was it able to change? rate had also declined by 2012. 2. Expressing Viewpoints Do you approve of all How did Thailand make such major changes with limited of the strategies that the government of Thailand resources? Demographers believe the changes are due to employed in order to reduce their population the combination of strategies shown in the table above. growth? Do the goals justify the strategies they used? Write a persuasive paragraph to defend your opinion.

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Figure 2.6

Reducing Population China has implemented a long campaign to reduce birth rates. Strategies have included economic rewards for single-child families and advertising such as the billboard shown here.

Managing Development and Population Growth Check for Understanding Humans throughout history have witnessed the negative effects of Recognize What are two examples of population growth. Today, less-developed countries know that continued strategies that a government might use population growth can limit their economic development. The govern- to try to limit population growth? ments of some countries, such as China, Thailand, and India, have tried to reduce birth rates using public advertising, as shown in Figure 2.6, Figure 2.7 family planning programs, economic incentives, or legal punishments. MDG by 2015 In 1994, the United Nations held the International Conference on Provide universal access to a full Population and Development (ICPD). This conference involved debates range of safe and reliable family- relating population, development, and the environment. Achievement of planning methods and related the Millenium Development Goals (MDG), as seen in Figure 2.7, that re- reproductive health services. sulted from the ICPD is targeted for 2015. Many countries favor stabilizing population growth, especially through improvements in women’s status. Reduce infant mortality rates to In fact, worldwide fertility rates are dropping, as shown in Figure 2.8. below 35 infant deaths per 1,000 live births and mortality rates of children under five years old to Figure 2.8 below 45 deaths per 1,000 live births. Worldwide Trends in Fertility Most countries’ fertility rates are dropping toward replacement level. Close the gap in maternal mortality 7 between developing and developed Least developed regions countries. Achieve a maternal 6 mortality rate below 60 deaths per Less developed regions 100,000 live births. 5 World Increase life expectancy at birth to 4

more than 75 years. In countries 3 with the highest mortality, increase life expectancy at birth to more than 2 70 years. More developed regions

Total fertility (children per woman) 1 Increase universal access to and completion of primary education, 0 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 and redress gender imbalances at (projected) Year higher levels of education. Source: UN Population Division.

Source: UN Population Fund. Works ©Louise Gubb/The Image

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QUICKLAB Growth Is Slowing QUICKLAB The human population of the world is now more than 7 billion and is Estimating Population Growth still increasing. The worldwide population growth rate peaked at about Procedure 87 million people per year between 1985 and 1990. In contrast, the 1. Using statistics based on United Nations figures (below), construct population grew by 81 million people per year from 1990 to 1995. a line graph showing the growth of Fertility rates have declined since about 1970 in developed and less- the world’s population from the year developed regions. However, rates are still much higher in less-developed 1000 until the year 2011. regions. Demographers predict that this trend will continue and that 2. If the world’s population continues global population growth will be slower in this century than in the last to grow at its current rate, use your century. If current trends continue, most countries will have replacement graph to predict what the global level fertility rates by 2050. If so, world population growth would even­ population will be in the years tually stop. However, ways must be found to make fewer resources stretch 2100 and 2200. much further, in order for Earth to sustain its human population. Year Population (in billions) 1000 0.31 Projections to 2050 1100 0.35 1200 0.38 Figure 2.9 shows United Nations projections of population growth to 2050. 1300 0.43 The medium-growth line, predicted by most demographers, assumes that 1400 0.47 global fertility rates will decline to replacement level by 2050. The high- 1500 0.50 and low-growth lines would result from higher or lower fertility rates. 1600 0.65 1700 0.70 Figure 2.9 1800 0.98 1900 1.65 Projections Current fertility trends will result in a world population of about 9 billion in 2000 6.06 2050 (middle line). Economic or political changes could lead to higher or lower numbers. 2011 7.00 World Population Projection for Different Growth Rates 12 Analysis High growth rate 1. Based on your graph, is the 10 population of the world still Medium growth rate growing at the rate it was in the 8 year 1000? Explain.

6 Low growth rate

4

World population (in billions) 2

0 1950 2000 2050 Year (projected) SectionSource: UN Population 2 Division.Formative Assessment

Reviewing Main Ideas Critical Thinking 1. Describe three problems caused by rapid 4. Analyzing a Viewpoint Write a comparison of human population growth. the pros and cons of the strategies nations have used to reduce population growth. 2. Compare population growth in more- developed countries to population growth 5. Analyzing Relationships Do you think that in less-developed countries. changing birth rates will by themselves cause a nation to undergo further development? 3. Describe worldwide population projections for the next 50 years.

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Maps in Action Fertility Rates and Female Literacy in Africa

Female literacy vs fertility rates

MAP SKILLS Use the map of Africa to answer the questions below.

1. Describing Locations Which regions of Africa have 3. Comparing Data Worldwide, the average total the highest female literacy (percentage of females who fertility rate is about 2.8 children per woman, and the can read and write)? the lowest female literacy? Which average female literacy is 74 percent. How does Africa regions have the highest fertility rates? the lowest compare with the rest of the world in both aspects? fertility rates? 2. Analyzing Data Choose 20 countries and make a graph comparing the total fertility rates and female literacy of each country.

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Society and the Environment ECOZine Go online for the latest environmental science at HMDScience.com news and updates on all EcoZine articles.

Lost Populations: These large stone figures found on Easter Island were What Happened? made by a civilization that has disappeared.

At various points in human history, entire populations have disappeared and left mysterious remains such as the Egyptian pyramids and the Anasazi pueblos in the southwestern United States. Why did these people and their civilizations disappear? Archeologists sometimes find evidence that environmental destruction was one of the reasons the populations disappeared.

Rapa Nui (Easter Island) On the island of Rapa Nui, in the Pacific Ocean, the first European visitors were amazed to find huge stone heads that were kilometers from the quarries where the heads had been made. It seemed impossible that the islanders could have moved the heads. There were no horses, oxen, or carts on the island and there were also no trees, that could have been used as rollers to move the heads. The islanders were using grass and reeds to make fires because the island was barren which are used to identify plants, show that the island was grassland. once covered by a forest that contained many species found nowhere else in the world. A Changed Environment But by 1600 ce trees were rare and the Easter Island palm Researchers have now shown that Rapa Nui was very tree was extinct. The palm seeds were probably eaten by different when it was first colonized by Polynesians rats that the Polynesians had brought to the island. With the around 1200 ce. In the oldest garbage heaps on the island, destruction of the forest, every species of native land bird also archaeologists have found that one-third of the bones came became extinct. With the added stress of disease carried by from dolphins. To hunt dolphins, the islanders must have had the European visitors, the local human population crashed. strong canoes made of wood from tall trees. Pollen grains, The people of Easter Island destroyed their environment by overusing its natural resources and introducing new species such as chickens and rats. The people were reduced from a complexWhat civilization Do You to a Think? primitive lifestyle. Easter Island is a small-scale example of what ecologists worry could happen to Earth’s entire human population.

What Do You Think?

Industrialized countries have started to invest in environmental improvements, such as replanting forests that have been destroyed and protecting endangered species. Do you think These ruins in New Mexico were built by the Chaco this makes these countries safe from the kind of Anasazi civilization around 900 ce. Environmental changes environmental disasters that destroyed the Easter are thought to have affected this population. Island civilization? (b) ©Walter Rawlings/Robert Harding World Imagery/GettyWorld Images; (t) ©Getty Images Rawlings/Robert Harding (b) ©Walter

Chapter 9: The Human Population 233 printcode=a DO NOT EDIT--Changes mustbemadethrough “File info” 234 Chapter 9 Section 2 Section 1 Populations Unit 3:

Trends Changing Population Populations Studying Human Summary • • • Objectives • • • Objectives each regionindividually. closely thismodel, follow soitisimportanttoexamine rates,death size. andpopulation Notallcountries ofchangeinbirthrates,progress through fourstages transitionmodel,In thedemographic countries migration, andlifeexpectancy. structure, suchasage data survivorship, fertilityrates, trendsusing topredictpopulation try Demographers scientific revolutions. production, whichaccom­ were improvementsinhygieneandincreasesfood last fewcenturies. The mainreasonsforthisgrowth inthe hasaccelerated growth Human population citizens. economic incentives, orlegalpunishmentsfortheir through publicadvertising, familyplanningprograms, directly to reducebirthrates Some countriesattempt themore-developed countries did. that transitioninthesameway through thedemographic developed orlessdeveloped. Notallcountriesaregoing In thiscentury, countriesmaybelabeledmore affected arefuelwood, water, andarableland. they canberenewed, theresourcesmostcritically usesresourcesfasterthan population When agrowing panied theindustrialand demographic demographic life expectancy migration fertility rate survivorship structure age demography Key Terms least developed urbanization arable land infrastructure Key Terms transition countries

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Chapter 9 Review

Reviewing Key Terms 13. The demographic transition is a(n) Use each of the following terms in a separate sentence. a. untested hypothesis. 1. demography b. natural law. 2. demographic transition c. model based on observed patterns. 3. infrastructure d. international law. 4. least developed countries 14. A country in the second stage of the demographic transition may have all of the following except For each pair of terms, explain how the meanings of the terms differ. a. increasing agricultural production. 5. age structure and survivorship b. improving healthcare and education. 6. infant mortality and life expectancy c. decreasing population size. 7. death rate and fertility rate d. decreasing death rates. 8. urbanization and migration 15. Which of the following resources is likely to 9. Concept Map Use the following terms to be impacted the most by a rapidly growing create a concept map: rapid human population population? growth,demographic transition, survivorship, a. clothing fertility rate, fuelwood, water, and land. b. food c. housing Reviewing Main Ideas d. water 10. Age structure data include all of the following except 16. Which of the following diseases is often spread a. the number of members of a population who through unsafe public water sources? are between 5 and 11 years old. a. dysentery b. the ratio of males to females in a population. b. flu c. the amount of population change due to immigration or emigration. c. chickenpox d. the ratio of older people to younger people in d. AIDS a population. 17. Which of the following uses of wood is the most 11. Human population growth accelerated in recent important for basic human needs? centuries mostly because of a. heating the home a. the bubonic plague. b. boiling water b. better hygiene and food. c. making tools c. the discovery of electricity. d. building shelter d. improved efficiency of fuel use. 18. In this century, the world population is likely to 12. Which countries have Type I survivorship? a. remain the same. a. the most developed countries b. continue to grow exponentially. b. the least developed countries c. decline rapidly because fertility rates are c. countries in the second stage of the already below replacement level. demographic transition d. stabilize after fertility rates fall below d. countries in the first stage of the demographic replacement level. transition

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Chapter Review

Short Answer Critical Thinking 19. What are the main reasons that life expectancy 28. Analyzing Predictions Why are human has increased worldwide? population trends difficult to predict? Describe an example of an event that would change most 20. How does the age structure of a population help demographic predictions. predict future population growth? 29. Analyzing Methods In what ways does the 21. What is the relationship between education and study of human populations differ from the study fertility rates in a human population? of wildlife ecology? 22. Which properties of a population change during 30. Identifying Relationships What other factors, the demographic transition? besides those already mentioned, might have an 23. Which key resources are impacted the most by effect on fertility rates in a given population? rapidly growing populations? 31. Evaluating Theories Write an evaluation of 24. Which regions of the world are generally more the demographic transition as a theory of how developed? less developed? populations will develop. How useful is the demographic transition model in predicting the future? What assumptions are made by the Interpreting Graphics theory? What criticisms could be made of the The graph below shows each region’s contribution theory? to world population growth. Use the graph to answer 32. Careers Demographers are employed by many questions 25–27. kinds of organizations including governments, 25. Determine Which region(s) are projected to health organizations, and insurance companies. increase in population size? How can their skills be useful to each of these 26. Predict Which region(s) are projected to decline organizations? in population size? 33. Social Studies Find out the demographic 27. Explain Can you assume that all the countries history, for the last 100 years, of a developing within each region have the same growth country of your choice. Explain how closely this patterns? Explain your answer. country’s pattern of development follows the demographic transition model. 34. Research Demographic Trends Look up World Population Growth by Region 9,000 population statistics for your local city, county, or state. Read and take notes about recent 8,000 Asia demographic trends and predictions for the next 7,000 Africa few decades. Make a summary of your findings. Latin America 6,000 Europe 5,000 Northern America (U.S., Canada, 4,000 Greenland)

3,000

2,000 World population (in millions) 1,000

0 1750 1800 1850 1900 1950 1999 2050 Year (projected)

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Chapter Review

Analyzing Data CASESTUDY Use the graph below to answer questions 35–37. STUDYSKILL 40. According to the article, for what reasons 35. Analyzing Data At which times did the fertility did Thailand decide to reduce the size of its rate change most drastically in the United States? population? 36. Graphing Data Sketch a copy of the graph 41. After reviewing the case study, explain the below. Smooth the bumps to give an idea of relationship it indicates between reducing general trends. Whypopulation It Matters size and improving the lives of 37. Drawing Conclusions On your new graph, women. draw a second line to show the changes in population size that you would predict to result Why It Matters from the given fertility rates over time. 42. Why should people in the United States Baby boom Baby bust be concerned about 4.0 population size in

3.5 other countries?

e t a r y t

i 3.0 l i t r e f

Replacement l a

t 2.5 level o T

2.0

1.5 1920 1930 1940 1950 1960 1970 1980 1990 2000 Year Source: National Center for Health Statistics. STUDYSKILL Making Connections Quantitative Terms Look for key terms in the graphs 38. Writing Persuasively Write an opinion article in this chapter. In your science journal, copy the graphs and for a newspaper or magazine. Argue either for or write brief descriptions of how key terms may relate to the against a policy related to immigration or family graphs and to other key terms. For example, copy Figure 3, planning. and write “High infant mortality results in low life expectancy and Type III survivorship.” 39. Writing Using Research Look up recent census data from your city, county, or state. Write a paragraph that describes the major demographic trends of the last few years. ©Syndicated Features Limited/The Image Works Limited/The Image©Syndicated Features

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ExplorationLab Data Analysis How Will Our Objectives Predict which variable has a Population Grow? greater effect on population growth rates. If you were a demographer, you might be asked to determine how a population is likely to change in the future. You have learned that the rate Calculate changes for a given population over a of population growth is affected by both the number of children per family 50-year period. and the age at which people have children. But which factor has a greater effect? To explore this question, you will use age-structure diagrams—also Graph the resulting called population pyramids—such as the one shown below. population’s age structure by creating a population pyramid. Procedure Compare the effects 1. In this lab you will calculate future population trends for an imaginary of fertility variables on city. To compare how fertility variables may affect population growth, population growth rates. each group of students will test the effects of different assumptions. Assume the following about the population of this city: Materials calculator or computer Assumptions About the Population colored pencils or markers graph paper • Half the population is male and half is female. notebook • Every woman will have all of her children during a given pen or pencil five-year period of her life. ruler • Everyone who is born will live to the age of 85 and then die. • No one will move into or out of the city.

2. Your teacher will divide the class into four groups. Each group will project population growth using the following assumptions:

United States, 2000 Assumptions About the Women 80+ in the Population 75–79 Males Females 70–74 Group Each Woman Gives Birth to While in the Age Range of 65–69 60–64 55–59 A 5 children 15–19 50–54 Age 45–49 B 5 children 25–29 40–44 35–39 30–34 C 2 children 15–19 25–29 20–24 D 2 children 25–29 15–19 10–14 5–9 0–4 3. Predict which of the four groups will have the greatest population 12 8 4 0 4 8 12 growth in 50 years. Write down the order you would predict for Population (in millions) the relative size of the groups from largest population to smallest population. Age Structure You will make an age- structure diagram, such as this graph of the U.S. population in 2000. 4. The table at right shows the population of our imaginary city for the year 2000. Use the data in the table to make an age-structure diagram (population pyramid) for the city. Use the example diagram at left to help you.

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5. Make a table similar to the one shown at right. Add columns for the Population in Each Age years 2005, 2010, and for every fifth year until the year 2050. Group, 2000–2050 6. Calculate the number of 0- to 4-year-olds in the year 2005. To do this, Age 2000 2005 2010 first determine how many women will have children between 2000 and 2005. Remember that half of the population in each age group is 80+ 100 female, and that members of the population will reproduce at specific ages. Multiply the number of childbearing women by the number of 75–79 500 children that each woman will have. For example, Group A will have 70–74 600 12,500 new births by 2005. 65–69 700 7. Fill in the columns for the years 2005 and 2010. Determine the num- ber of people in each age group by “shifting” each group from 2000. 60–64 800 For example, the number of 5- to 9-year-olds in 2005 will equal the number of 0- to 4-year-olds in 2000. 55–59 900

8. Calculate the total population for each five-year period. 50–54 1,000

9. Repeat the process described in steps 3–8 for each column to 45–49 1,250 complete the table through the year 2050. 40–44 1,500

Analysis 35–39 2,000 1. Constructing Graphs Plot the growth of the population on 30–34 2,500 a line graph. You may want to use a computer to graph the results. 25–29 3,000 2. Constructing Graphs Make a population pyramid for the popula- tion in 2050. 20–24 4,000

15–19 5,000 Conclusions 3. Evaluating Data Compare your graphs with the graphs of the other 10–14 6,500 three groups. Were your predictions correct? 5–9 8,000 10,000 4. Drawing Conclusions Which variable had a greater effect on popu- 10,000 lation growth—the number of children each woman had or the age at 0–4 12,500 which each woman had children? Total 48,350 5. Interpreting Information Did any of the groups show no growth in Females the population? Explain these results. that give 2,500 birth New Extension 12,500 births 6. From the age-structure diagram on the previous page, what would you predict to happen to the U.S. population in the next 20 years? in the Sample Population Data Use this table as next 50 years? What parts of the age structure are most important to an example to calculate the age structure for these predictions? each generation of your imaginary population. Add columns for five-year periods up to 2050. Examples of some of Group A’s results are shown in red.

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