Chapter 7: Human Populations

Demographic Implication if Living Longer

-A population growing rapidly due to natural increase has more young people than does a stationary population -Even if total fertility rates were to fall, the population would continue growing as young people enter reproductive age (population momentum) -Some countries now have a stable population with the same number of people in each age group -Declining populations have more old people than young people

Living Longer has Implications

-Both rapidly and slowly growing countries can have a problem with dependency ratio -The number of non-working compared to working individuals in a population. -In the U.S., fewer working-age people will have to support many more retired people, and this is a problem for the Social Security system. -Similar problems are developing in other countries around the world causing countries to rethink their population policies

Women's Rights and Fertility

-Education and job opportunities for women reduce fertility rates -When child mortality is high, parents tend to have high numbers of children to ensure that at least some survive. Improving child survival would reduce the number of births -Land reform, political rights, job opportunities for women, and improved health for women translate into better survival for children and therefore lower fertility

Environmental Effects of Population

-Effects of population on the environment are not due to numbers alone. I = PAT I=environmental impact P = population size A = affluence T = technology -A single American living an affluent lifestyle produces more pollution than an entire village of farmers in Africa

Population growth

-Every second 4.3 children are born and 4 people die. There is a net gain of roughly 0.3 persons per second. -Current world population is greater than 7.7 billion and growing at 1.09% per year. -Global population will double in 65 years if conditions remain unchanged. -Ecologists are concerned that overpopulation will cause environmental degradation that will threaten the ecological life-support systems on which we depend -Economists often disagree with ecologists, arguing that economic and technological growth will enable us to solve these problems -Social justice advocates argue that the root cause of the problem is inequitable distribution of the Earth's resources

Pronatalist Pressures

-Factors that increase the desire for children -Source of pleasure, pride, comfort -Source of support for elderly parents -Current source of family income and labor -Social status -Replace members in society as they -Society's need to replace its members may be codified into cultural or religious values -Families with few children are pitied -Controlling fertility may be taboo -In some cultures, boys are valued more than girls because they carry on the family name and often are expected to financially support parents in old age -Couples may have more children than they really want in order to have a boy -Having a large family in some cultures is a source of male pride

Birth Reduction Pressures

-In developing countries, higher-income often means families can afford more children, thus fertility often increases, rather than decreasing as it does in developed countries -In less-developed countries, adding another child to a family usually does not cost much, while in developed countries, raising an additional child can carry a significant cost -Higher education and personal freedom for women often result in decisions to limit childbearing. -When women have more opportunities to earn a salary, they are less likely to have many children. -Education and socioeconomic status are usually inversely related to fertility in wealthier countries

Exponential Growth

-It took thousands of years to reach 1 billion people (in 1804). -It took 150 years to double that to 3 billion (in 1960). -The increase from 5 to 6 billion took only 12 years. -Another way to look at it, is that the Earth's population tripled in the twentieth century.

Emigration and Immigration

-Migration plays a large role in human population dynamics. -In 2018, UNHCR reported that more than 65 million people were displaced by economics, politics, persecution, or war. 25 million of these moved to other countries -Climate change could account for mass migration of millions

Can more people be beneficial?

-More people mean larger markets, more workers, and increased efficiency due to mass production. -Greater numbers also provide more intelligence and enterprise to overcome problems. -Economist Julian Simon believes that human ingenuity will be able to solve the problems associated with population growth.

Could We Have a Birth Dearth

-Most European countries, as well as Japan, Singapore and Taiwan, are experiencing negative growth rates -There are concerns in all these countries about a lack of young people to be soldiers, workers, and taxpayers -One reason that birth rates may have dropped in developed countries is that toxins and endocrine disrupts that are pollutants interfere with sperm production. Sperm numbers and quality have fallen by half in the last 50 year

Factors that Complicate Family Planning

-Often, societal changes must first take place before family planning programs will be successful -Improved education and economic status for women -Improved status for children -Increased sense of social responsibility -Financial and political stability -Effective and acceptable birth control methods

Social Justice

-Still other demographers believe that in order for the demographic transition model to work, resources must be distributed more equitably -They believe that the world has enough natural resources, but inequitable social and economic systems cause distributional -Many rich countries, when they were colonial powers, extracted the wealth from countries that were their colonies. Some of the world's poorest countries had rich resources and adequate food supplies before they were impoverished by colonialism

Technology can increase carrying capacity

-Technology can boost carrying capacity as we make progress in agriculture, engineering, commerce and medicine. These achievements make it possible to support many more people per unit area. -However, much of our growth has been based upon cheap, abundant fossil fuels. Will rising fuel prices constrain food production and distribution?

Perspectives on Growth

-Thomas Malthus (1798) wrote An Essay on the Principle of Population in which he showed that human populations increase exponentially. -Population growth is checked by famine, disease, and cultural factors (for example, late marriage). -Debate about whether human population growth causes environmental degradation (Malthus) or whether human population growth results from poverty and resource depletion (Karl Marx). -These two viewpoints are still debated today

Population Growth is a Recent Event

-Until the invention of agriculture 10,000 years ago, the human population was a few million people. -Populations were held in check by diseases, famine and war. -Early societies regulated their population through cultural taboos, abstinence and infanticide. -Human population began to increase rapidly after 1600 due to agricultural developments, better sources of power, and better health care and hygiene

Other Rights

-We should consider the rights of other species. -Perhaps, rather than asking what is the maximum number of people that Earth can hold, we should instead ask what is the optimum number of people at which we can provide a fair and decent life for all humans while causing the minimum impact on other species

Family Planning

Allows couples to determine the number and spacing of their children

Birth Control

Any method used to reduce births

In a mature industrial economy (Stage 3)

Birth rates begin to fall as people see that most of their children survive -Populations continue to grow due to population momentum

Economic Development (Stage 2)

Brings better standard of living thus death rates fall. Birth rates stay constant or even rise.

Natural Increase

Crude birth rate minus crude death rate

Factors Affecting Population Growth

Development, life expectancy, age distribution, and social factors can explain the differences in growth rates for different countries

Demography

Encompasses vital statistics about people such as births, deaths, distribution, and population size -The estimated world population in 2018 was 7.7 billion. -An educated guess. Many people remain uncounted. Some nations overstate or understate their numbers for political reasons

Decline in Fertility rates worldwide

Fertility rates have declined everywhere except some countries in sub-Saharan Africa

Demographic Transitions Happening Now?

Four conditions necessary for demographic transition: -Improved standard of living -Confidence that children will survive -Improved status of women -Availability and use of birth control. -Some demographers think that a demographic transition is taking place now in developing nations.

Total Growth Rate

Includes immigration, emigration, births and deaths

Traditional Methods

Long breast-feeding (suppresses ovulation), taboos against intercourse while breast-feeding, celibacy, folk medicines, abortion, infanticide

Crude Birth Rate

Number of births in a year per thousand. (Not adjusted for population characteristics such as number of women of childbearing age)

Total Fertility Rate

Number of children born to an average woman in a population during her life

Crude Death Rate

Number of deaths per thousand persons in a given year -Poor countries average about 20 while wealthier countries average about 10. -Some rapidly growing countries have very low crude death rates due to a high proportion of young people

Replacement Fertility Rate

Occurs when birth rates just compensate for deaths. The rate is 2.1 children per couple, not 2.0, because some people do not have children and some children do not survive to reproductive age

Demographic Transition

Pattern of falling death rates and birth rates due to improved living conditions accompanying economic development

Pre-Modern Society (Stage 1)

Poor conditions keep death rates high; birth rates are correspondingly high

Life expectancy

The average age a newborn can expect to attain in any given society

Life Span

The oldest age to which members of the species survive

Developed Countries (Stage 4)

Transition is complete and both death and birth rates are low and population is in equilibrium