2 The human population and its impact Core Case Study: Slowing Population Growth in China: A Success StoryChina is the most populated country in the world with 13 billion people.In the 1960s the population was growing so rapidly that there was a threat of mass starvation.China reduced their population growth by promoting one-child families.The government provides contraceptives, sterilizations, and abortions for married couples. In addition, married couples pledging to have no more than one child receive a number of benefits including better housing, more food, free health care, salary bonuses, and preferential job opportunities for their child. Couples who break their pledge lose such benefits.
3 6-1 How Many People Can the Earth Support Human Population Growth Continues but is Unevenly DistributesThere are three major factors that account for population increase: First, humans developed the ability to expand into almost all of the planet’s climate zones and habitats. Second, then emergence of early and modern agriculture allowed us to grow more food for each unit of land area farmed. Third, death rates dropped sharply because of improved sanitation and health care and development of antibiotics and vaccines to help control infectious diseases.It took from the time we arrived on the earth until about 1927 to add the first 2 billion people to the planet; less than 50 years to add the next 2 billion (by 1974); and just 25 years to add the next 2 billion (by 1999).The world’s population is growing at a rate of about 1.21% a year.The more developed countries are growing at a rate of 0.17% a year and the middle-and low-income, less-developed countries are crowing at a rate of 1.4% a year, this is 9 times faster.
4 6-2 what factors influence the size of the human population? The Human Population Can Grow, Decline, or Remain Fairly StableIf there are more births than deaths during a given period of time, the earth’s population increases, and when the reverse is true, it decreases. When the number of births equals the number of deaths during a particular time period, the global population size does not change.Crude birth rate: the number of live births per 1,00 people in a population in a given year. Crude death rate: the number of deaths per 1,000 people in a population in a given year.The growth or decline of a population depends on three things; births, deaths, and migration.Population change can be calculated by subtracting the number of people leaving a population (death and emigration) from the number entering it (births and immigration) during a specific period of time (usually one year).
5 6-2 what factors influence the size of the human population? Continued… Women Are Having Fewer Babies by Not Few Enough to Stable the World’s PopulationFertility rate: the number of children born to a woman during her lifetime.There is two types of fertility rates that affect population size and growth rate: replacement-level fertility rate; the average number of children that couples in a population must bear to replace themselves, and total fertility rate (TFR); the average number of children born to women in a population during their reproductive years.Between 1955 and 2010, the average TFR dropped from 2.8 to 1.7 children per woman in more-developed countries and from 6.2 to 2.7 in less-developed countries. The average TFR for less- developed countries is projected to continue dropping , while that for more-developed countries is likely to rise slightly.
6 6-2 what factors influence the size of the human population? Continued… Case Study: The U.S. Population Is Growing RapidlyThe population of the US grew from 76 million in 1900 to 310 million in 2010.It took the country 139 years to add its first 100 million people, 52 years to add another 100 million by 1967, and only 39 years to add the third 100 million by 2006.During the baby boom ( ), 79 million people were added to the US population.The TFR has decreased from 3.7 children per woman during 1957 to 2.1 children per woman in 2010, and most years since.The drop in TFR has slowed the rate of population growth in the US, but the countries population is still growing faster than those of all other more-developed countries.The U.S. Census Bureau projects that the U.S. population is likely to increase from 310 million in 2010 to 423 million by 2050.
7 6-2 what factors influence the size of the human population? Continued… Several Factors Affect Birth and Fertility RatesMany times in less developed countries, children are needed in the work force, therefore the parents have many children to help with the daily necessities.In more-developed countries, the birth and fertility rates are low because raising children are much more costly because they do not enter into the work force until their late teens or twenties.The availability of, or lack of, private and public pension systems can influence the decision of some couple on how many children they have.There are more infant deaths in poorer countries, so having several children might insure the survival of at least a few.People living in urban areas usually have better access to family planning services and tend to have fewer children than do those living in rural areas.
8 6-2 what factors influence the size of the human population? Continued… Several Factors Affect Birth and Fertility Rates (Continued)TFR tend to be low when women have access to education and paid employment outside the home.Women normally have fewer children when their average age at marriage is 25 or older.Each year, about 190 million women become pregnant, and at least 40 million get abortions– about 20 million legal and 20 million illegal and unsafe.The availability of reliable birth control methods allows women to control the number and spacing of the children they have.Religious beliefs. Tradition, and cultural norms also play a role
9 6-2 what factors influence the size of the human population? Continued… Several Factors Affect Death RatesIn less developed countries, more people have started living longer and fewer infants died, this is due to the increase in food supplied and distribution, better nutrition, medical advanced such as immunizations and antibiotics, improved sanitation, and safer water supplied.Life expectancy: the average number of years a newborn infant can be expected to live.Infant mortality rate: the number of babies out of every 1,000 born who die before their first birthday.In the world’s poorest countries, there is a larger death rate due to AIDS and internal strife.Infant mortality is one of the best measures of a society’s quality of life because it reflects a country’s general lever of nutrition and health care.Child mortality rate: the annual number of deaths among children under age 5 per 1,000 live births.The most common cause of child mortality in many less-developed regions is the use of contaminated water for drinking and washing, resulting in diarrheal diseases and other illnesses that are not as prevalent in more- developed countries.
10 6-2 what factors influence the size of the human population? Continued… Migration Affects an Area’s Population SizeMigration: the movement of people into (immigration) and out of (emigration) specific geographic areas.Most people migrating from one area or country to another seek jobs and economic improvement. But religious persecution, ethnic conflicts, political oppression, wars, and certain types of environmental degradation such as soil erosion and water and food shortages drive some to migrate.Case Study: The United States: A Nation of ImmigrantsSince 1820, the United States has admitted almost twice as many immigrants and refugees as all other countries combined.Currently, legal and illegal immigration account for about 36% of the country’s annual population growth.
11 6-3 How does a population’s age structure affect its growth or decline? A Population’s Age Structure Helps Us to Make ProjectionsAge structure: the numbers or percentages of males and females in young, middle, and older age groups in that population.There are there stages of a age-structure diagram: prereproductive (ages 0-4), consisting of individuals normally too young to have children; reproductive (ages ), consisting of those normally able to have children; and postreproductive (ages 45 and older), with individuals normally too old to have children.A country with a large percentage of its people younger that age 15 (wide base) will experience rapid population growth unless death rates rise sharply.The fastest growing age group is seniors– people who are 65 and older.The senior population is growing due to declining birth rates and medical advances that have extended our lifespans.
12 6-3 How does a population’s age structure affect its growth or decline 6-3 How does a population’s age structure affect its growth or decline? Continued…Case Study: The American Baby BoomChanges in the distribution of a country’s age groups have long-lasting economic and social impacts.The baby boom added 79 million people to the U.S. population, and make up 36% of all adult AmericansThey have greatly influenced the US economythe baby-boom generation plays an increasingly important role in deciding who gets elected to public office and what laws are passed.
13 6-3 How does a population’s age structure affect its growth or decline 6-3 How does a population’s age structure affect its growth or decline? Continued…Populations Made Up Mostly of Older People Can Decline RapidlyIf population decline is gradual, its harmful effects usually can be managed.A rapid population decline can lead to severe economic and social problems.The large group of older people can put severe strains on the government budgets because these individuals consume an increasingly larger share of medical care, pension funds, and other costly public services, which are funded by a decreasing number of working taxpayers.Causes the country to face labor shortages, unless they rely more heavily on automation or massive immigration of foreign workers.
14 6-3 How does a population’s age structure affect its growth or decline 6-3 How does a population’s age structure affect its growth or decline? Continued…Populations Can Decline Due to a Rising Rate: The AIDS TragedyWhen there is a large number of deaths from AIDS can disrupt a country’s social and economic structure by removing significant numbers of young adults from its population.AIDS kills about 2 million people a year (including 22,000 in the United States, 39,000 in China, 140,000 in Zimbabwe, and 350,000 in South Africa).The change caused in the young-adult age structure of a country has a number of harmful effects such as; a sharp drop in average life expectance and the loss of productive young adult workers and trained personnel.
15 6-4 How can we slow human population growth? The First Step is to Promote Economic DevelopmentThe three most important steps toward the goal of slowing or stopping population growth are: to reduce poverty primarily through economic development and universal primary education, to elevate the status of women, and to encourage family planning and reproductive health care.Demographic transition: as countries become industrialized and economically developed, first their death rates decline and then their birth rates decline.It is believed that most of the world’s less-developed countries will make a demographic transition over the next few decades. But it is also believed by some that rapid population growth, extreme poverty, and increasing environmental degradation in some low-income countries could leave them in the second stage of demographic transition.Failing states: are countries where the national governments can no longer ensure the personal security of most of their people.
16 6-4 How can we slow human population growth? Continued… Empowering Women Helps to Slow Population GrowthWomen tend to have fewer children if they are educated, have the ability to control their own fertility, earn an income of their own, and live in societies that do not suppress their rights.Women do most of the world’s domestic work and child care for little or no pay“For poor women, the only holiday is when you are asleep.”Women account for two-thirds of all hours worked but receive only 10% of the worlds income, and they own less than 2% of the worlds land. Women make up for 70% of the world’s poor and 64% of its 800 million illiterate adults.Poor women who cannot read often have an average of 5 to 7 children, compared to 2 or fewer children in societies where almost all women can read.
17 6-4 How can we slow human population growth? Continued… Promote Family PlanningFamily planning provides educational and clinical services that help couples choose how many children to have and when to have them.Family planning has decreased the number of births throughout the world, reduced the number of abortions performed each year, and it has decreased the number of mothers and fetuses dying during pregnancy.Family planning also has financial benefits, such as saving money in health, education, and social service cost by preventing unwanted births.Despite family planning, two problems still remain; First, 42% of all pregnancies in les-developed countries are unplanned and 26% end with abortion, second, an estimated 201 million couples in less-developed countries want to limit their number of children and determine their spacing, but they lack access to family planning services.
18 6-4 How can we slow human population growth? Continued… Case Study: Slowing Population Growth in IndiaThe worlds first national family planning program began in India in 1952The Indian government provides family planning services throughout the country and strongly promotes a smaller average family size.Only 48% of the couples in India acutely use a modern birth control method.
19 The chapters three big ideas! The human population is increasing rapidly and may soon bump up against environmental limits.Even if population growth were not a serious problem, the increasing use of resources per person is expanding the overall human ecological footprint and putting a strain on the earth’s resources.We can slow human population growth by reducing poverty through economic development, elevating the status of women, and encouraging family planning.
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