APES CH 8: Human Population

rate of natural increase

-(also called the natural rate of population change) -change due to birth and death rates alone, excluding migration

age structure (demography)

-Age structure describes the relative numbers of individuals of each age class within a population. -Data on age structure are especially valuable to demographers trying to predict future dynamics of human populations. -A population made up mostly of individuals past reproductive age will tend to decline over time. -In contrast, a population with many individuals of reproductive age or pre-reproductive age is likely to increase. -A population with an even age distribution will likely remain stable as births keep pace with deaths.

age structure diagrams

-Age structure diagrams, often called population pyramids, are visual tools scientists use to illustrate age structure. -The width of each horizontal bar represents the number of people in each age class. -A pyramid with a wide base denotes a large proportion of people who have not yet reached reproductive age—and this indicates a population soon capable of rapid growth. -In this respect, a wide base of a population pyramid is like an oversized engine on a rocket—the bigger the booster, the faster the increase.

pre-industrial revolution: family mindset for growth

-At the outset of the industrial revolution, population growth was universally regarded as a good thing. -For parents, high birth rates meant more children to support them in old age. For society, it meant a greater pool of labor for factory work.

India

-China is not alone in dealing with population issues. India, China's neighbor, is also a population powerhouse, and is only slightly less populous than China. -India lacks China's stringent reproductive policies, though, and soon will overtake China and possess the world's largest population.

why is it uncertain if China, even under a two child policy, will have two children?

-Chinese couples are used to the material wealth and urban lifestyle they enjoy: accepting the costs of raising a second child -In 2015, 60% of Chinese women of childbearing age were over 35, so many may not wish to (or be able to) conceive a second child. -In fact, an earlier survey from 2008 by China's family-planning commission reported that only 19% of the people they surveyed wished to have a second child. -It may therefore be that China's relaxing of the one-child policy came too late to defuse the pending time bomb the nation may experience as China's population grays in the midst of its rapid industrialization.

Earth's carrying capacity for humans

-Environmental factors set limits on our population growth, and the environment has a carrying capacity for our species, just as it does for every other. -From an evolutionary standpoint, we happen to be a particularly successful species, however, and so we have repeatedly increased this carrying capacity by developing technology to overcome the natural limits on our population growth. -As our population climbs well beyond 7 billion, we may yet continue to find ways to increase our carrying capacity and preserve at least some of our current quality of life. -Given our knowledge of population ecology and logistic growth, however, we have no reason to assume that human numbers on Earth can keep growing indefinitely.

environmental cost of demographic transition

-Environmental scientists estimate that for people of all nations to attain the material standard of living that North Americans now enjoy, we would need the natural resources of four-and-a-half more planet Earths. -Hence, whether developing nations (which include the vast majority of the planet's people) pass through the demographic transition is one of the most important and far-reaching questions for the future of our civilization and Earth's environment.

what factors have driven TFR downwards?

-Factors such as industrialization, improved women's rights, and quality health care have driven the TFR downward in many nations in recent years. -All these factors have come together in Europe, where the TFR has dropped from 2.6 to 1.4 in the past half-century. -Nearly every European nation now has a fertility rate below the replacement level, and populations are declining in 15 of 45 European nations. -In 2015, Europe's overall annual rate of natural increase (due to birth n death only) was between 0.0% and 0.1%.

Dhaka, Bangladesh

-Growing so fast, each new census is quickly outdated -megacity -Even traffic costs the city a lot of money Sewage polluting rivers, electricity and water networks struggle to meet demands -People living in slums don't have access to basic rights, because technically they are illegally residing where they are living

Why did Chinese leaders decide to institute a one child policy?

-However, the country's burgeoning population and its industrial and agricultural development were eroding the nation's soils, depleting its water, and polluting its air. -Realizing that the nation might not be able to continue to feed its people, Chinese leaders decided in 1970 to institute a population control program that prohibited most Chinese couples from having more than one child.

immigration and emigration

-Immigration and emigration play increasingly important roles in population change in our modern, international world. -People regularly relocate from one nation to another to improve their economic opportunities or to flee conflict or environmental degradation in their home nation. -Such migration can have significant effects on population growth in nations, such as the United States, that accept large numbers of immigrants.

Paul and Anne Ehrlich

-In our day, biologists Paul and Anne Ehrlich of Stanford University have been called "neo-Malthusians" because they too have warned that our population may grow faster than our ability to produce and distribute food. -In his best-selling 1968 book, The Population Bomb, Paul Ehrlich predicted that population growth would unleash famine and conflict that would consume civilization by the end of the 20th century.

what are the recent trends in country growth rates vs global growth rates?

-In recent decades, falling growth rates in many countries have led to an overall decline in the global growth rate. -This decline has come about, in part, from a steep drop in birth rates. -Note, however, that although the rate of growth is slowing, the absolute size of the population continues to increase. -Even though our percentage increases are getting smaller year by year, these are percentages of ever-larger numbers, so we continue to add more than 88 million people to the planet each year.

demographic transition: post industrial stage

-In the final stage, the post-industrial stage, both birth and death rates have fallen to low and stable levels. -Population sizes stabilize or decline slightly. -The society enjoys the fruits of industrialization without the threat of runaway population growth. -The United States is an example of a nation in this stage, although the U.S. population is growing faster than most other post-industrial nations because of a relatively high immigration rate.

demographic transition: industrial stage

-Industrialization increases opportunities for employment outside the home, particularly for women. -Children become less valuable, in economic terms, because they do not help meet family food needs as they did in the pre-industrial stage. -If couples are aware of this, and if they have access to birth control, they may choose to have fewer children. -Birth rates fall, closing the gap with death rates and reducing population growth.

demographic transition: transitional stage

-Industrialization initiates the second stage of the demographic transition, known as the transitional stage. -is generally characterized by declining death rates due to increased food production and improved medical care. -Birth rates in the transitional stage remain high, however, because people have not yet grown used to the new economic and social conditions. -As a result, population growth surges.

demographic transition trends

-Industrialization, he proposed, causes these rates to fall by first decreasing mortality and then lessening the need for large families. -Parents thereafter choose to invest in quality of life rather than quantity of children. -Because death rates fall before birth rates fall, a period of net population growth results. -Thus, under the demographic transition model, population growth is seen as a temporary phenomenon that occurs as societies move from one stage of development to another.

how are infant mortality rates and industrialization tied?

-Infant mortality rates vary widely around the world and are closely tied to a nation's level of industrialization. -China, for example, saw its infant mortality rate drop from 47 children per 1000 live births in 1980 to 16 children per 1000 live births in 2013 as the nation industrialized and prospered. -Many other industrializing nations enjoyed similar success in reducing infant mortality during this time period.

when did the worlds population reach 1 billion? (and future projections)

-It took until after 1800—which is recent when viewed in terms of human history—for our population to reach 1 billion. -Yet we reached 2 billion by 1930 and 3 billion in just 30 more years. Our population added its next billion in just 15 years, and it has taken only 12 years to add each of the next three installments of a billion people. -It is expected that the globe will be home to more than 9.7 billion people by 2050.

demographers (factors of demography!!)

-Just as population ecologists study such characteristics in other organisms, demographers study population size; density; distribution; age structure; sex ratio; and rates of birth, death, immigration, and emigration of people.

Thomas Malthus

-Malthus argued that unless population growth were controlled by laws or other social strictures, the number of people would eventually outgrow the available food supply. -Malthus's most influential work, An Essay on the Principle of Population, published in 1798, argued that if society did not limit births (through abstinence and contraception, for instance), then rising death rates would reduce the population through war, disease, and starvation.

HIV/AIDS: demographic fatigue

-Many nations in sub-Saharan Africa are experiencing such challenges -Because it removes young and productive members of society, AIDS undermines the ability of poorer nations to develop. -Nations lose billions of dollars in productivity when large numbers of its citizens are battling the disease, and treatment puts a huge burden on health care systems. -Children orphaned by AIDS further strain social safety nets, requiring interventions to prevent the cycle of poverty and disease from claiming yet another generation. -Improved public health efforts (including sex education, contraceptives, and intravenous drug abuse policies) have slowed HIV transmission rates in many nations, however, offering hope that these nations may escape the "trap" of demographic fatigue.

how are poorer nations being affected by population growth?

-Many of the world's poorer nations continue to experience substantial population growth. -Some of these nations are ill-equipped to handle such growth, and this leads to stresses on society, the environment, and people's well-being.

why does China have too few women?

-Modern China also has too few women. Chinese culture has traditionally valued sons because they carry on the family name, assist with farm labor in rural areas, and care for aging parents. -Daughters, in contrast, will most likely marry and leave their parents, as the traditional culture dictates. -Thus, when faced with being limited to just one child, many Chinese couples preferred a son to a daughter. -Tragically, this has led in some instances to selective abortion and the killing of female infants. -This has caused a highly unbalanced ratio of young men and women in China, leading to the social instability that arises when large numbers of young men are unable to find brides and remain longtime bachelors.

population size (demography)

-Our global human population of more than 7.3 billion is spread among 200 nations with populations ranging up to China's 1.37 billion, India's 1.31 billion, and the 321 million of the United States. -The United Nations Population Division estimates that by the year 2050, the global population will surpass 9.7 billion. -However, population size alone—the absolute number of individuals—doesn't tell the whole story. -environmental impact depends on its density, distribution, and composition (as well as on affluence, technology, and other factors outlined earlier).

Population Momentum

-Population growth that temporarily continues to occur AFTER the TFR drops to or below the replacement level. -A population will grow for years after the initial decrease as existing young people reach child bearing years. -Already have babies out there that have been born, going to have their own children. -Hard to turn a country around from this quickly -Public policy: govt might try to improve population growth and control, but there is a delay because of this momentum.

birth, death, immigration, and emigration (demography)

-Rates of birth, death, immigration, and emigration determine whether a population grows, shrinks, or remains stable. -The formula for measuring population growth also pertains to people: Birth and immigration add individuals to a population, whereas death and emigration remove individuals. -Technological advances have led to a dramatic decline in human death rates, widening the gap between birth rates and death rates and resulting in the global human population expansion.

replacement fertility rate

-Replacement fertility is the TFR that keeps the size of a population stable. -For humans, replacement fertility roughly equals a TFR of 2.1. (Two children replace the mother and father, and the extra 0.1 accounts for the risk of a child dying before reaching reproductive age.) -If the TFR drops below 2.1, population size in a given country (in the absence of immigration) will shrink. -many countries have fallen below TFR 2.1

is the demographic transition a universal process?

-The demographic transition has occurred in many European countries and other developed nations. -It is a model that may or may not apply to all developing nations as they industrialize now and in the future. -On the one hand, note how growth rates fell first for industrialized nations, then for less developed nations, and finally for least developed nations, suggesting that it may merely be a matter of time before all nations experience the transition. -On the other hand, some developing nations may already be suffering too much from the impacts of large populations to replicate the developed world's transition, a phenomenon called demographic fatigue.

demographic transition: pre-industrial stage

-The first stage, characterized by conditions that have defined most of human history. - both death rates and birth rates are high. -Death rates are high because disease is widespread, medical care is rudimentary, and food supplies are unreliable and difficult to obtain. -Birth rates are high because people must compensate for infant mortality by having several children and because effective methods of preventing pregnancy are not available. -children are valuable as workers who can help meet a family's basic needs. -Populations are not likely to experience much growth, which is why the human population grew relatively slowly until the industrial revolution.

How does the growing number of old people in China cause problems?

-The growing number of older Chinese individuals poses problems because the Chinese government lacks the resources to fully support them. -And because tradition dictates that Chinese sons care for their parents and grandparents in old age, this puts a heavy economic burden on the millions of only children produced under the one-child policy.

why are there typically more females than males in sex ratios?

-The naturally occurring sex ratio at birth in human populations features a slight preponderance of males; for every 100 female infants born, about 106 male infants are born. -This phenomenon is likely an evolutionary adaptation to account for the fact that males are slightly more prone to death during any given year of life. -A higher birth rate of males tends to ensure that the ratio of men to women will be approximately equal when people reach reproductive age. -Thus, a slightly uneven sex ratio at birth may be beneficial to some species. -However, a greatly distorted ratio can lead to problems.

How did China initially fare from the one child policy in the 70s?

-The program began with outreach efforts encouraging people to marry later and have fewer children. Along with these efforts, the Chinese government increased the accessibility of contraceptives and abortion. -Fertility declined with these initiatives, and by 1975 China's annual population growth rate had dropped from 2.8% to 1.8%.

how did Chinas age structure change with the one child policy?

-The rapid reduction in fertility that resulted from this policy drastically changed China's age structure. -Once consisting predominantly of young people, China's population has shifted, such that the numbers of children and older people are more even. -This means there will be relatively fewer workers for China's growing economy and proportionately larger numbers of older people relying on governmental support and services.

sex ratio (demography)

-The ratio of males to females also can affect population dynamics. -Note that population pyramids give data on sex ratios by representing numbers of males and females on opposite sides of each diagram.

demographic transition: Frank Notestein

-This is a model of economic and cultural change first proposed in the 1940s and 1950s by demographer Frank Notestein to explain the declining death rates and birth rates that have occurred in Western nations as they industrialized. -Notestein argued that nations move from a stable pre-industrial state of high birth and death rates to a stable post-industrial state of low birth and death rates.

Why have Ehrlich's predictions not come true?

-This is due, in part, to the way we have intensified food production in recent decades. -Population growth has indeed contributed to famine, disease, and conflict—but as we shall see, enhanced prosperity, education, and increasing gender equality have also helped to reduce birth rates.

how have infant mortality rates influenced population growth throughout much of human history?

-Throughout much of human history, parents needed to have larger families as insurance against the likelihood that one or more of their children would die during infancy. -Poor nutrition, disease, exposure to hostile elements, and limited medical care claimed the lives of many infants in their first year of life. -As societies have industrialized and become more affluent, infant mortality rates have plummeted as a result of better nutrition, prenatal care, and the presence of medically trained practitioners during birth.

rule of 70

-We can roughly estimate doubling times with a handy rule of thumb. -Just take the number 70 and divide it by the annual percentage growth rate: 70/1.2 = 58.3 (years)

Demography

-We exist within our environment as one species out of many. -As such, all the principles of population ecology apply to humans as well. -The application of principles from population ecology to the study of statistical change in human populations is the focus of demography.

what accounts for the unprecedented growth of the human population?

-What accounts for our unprecedented growth? As you may recall, exponential growth—the increase in a quantity by a fixed percentage per unit time—accelerates increase in population size, just as compound interest accrues in a savings account. -The reason for this pattern is that a fixed percentage of a small number makes for a small increase, but that the same percentage of a large number produces a large increase. -Thus, even if the growth rate remains steady, population size will increase by greater increments with each successive generation. -exponential growth endows small numbers with large consequences.

What led to China's initial population boom?

-When Mao Zedong founded the country's current regime six decades ago, roughly 540 million people lived in a mostly rural, war-torn, impoverished nation. -Mao's policies encouraged population growth, and by 1970 improvements in food production, food distribution, and public health allowed China's population to swell to 790 million people. -At that time, Chinese women gave birth to an average of 5.8 children in their lifetimes.

How has China attempted to address their 'time bomb'?

-by occasionally loosening the one-child policy and giving some citizens greater control of their reproductive choices. -For example, Chinese authorities announced in 2013 that if either member of a married couple is an only child, the couple would be allowed to have a second child—but only 1.5 million of the 11 million citizens eligible for this exemption applied for it. -Faced with the prospect of continued population issues, the Chinese government announced in October 2015 that the former one-child policy would immediately become a two-child policy, and couples would be permitted to have two children without penalty.

infant mortality rates

-improvements to our quality of life have been particularly successful in reducing infant mortality rates, the frequency of children dying in infancy. -Birth rates have not declined as much, so births have outpaced deaths for many years now. -Thus, our population explosion has arisen from a very good thing—our ability to keep more of our fellow human beings alive longer!

what are some effects of having a higher male population than female population?

-it has the undesirable social consequence of leaving large numbers of Chinese men single. -Without the anchoring effect a wife and family provide, many of these men leave their native towns and find work elsewhere as migrant workers. -Living as bachelors far from home, these men often engage in more risky sexual activity than their married counterparts. -Researchers speculate that this could lead to higher incidence of HIV infection in China in coming decades, as tens of millions of bachelors find work as migrant workers.

population density and distribution (demography)

-our distribution is clumped at all spatial scales. -at the global scale, population density is highest in regions with temperate, subtropical, and tropical climates -Population density is lowest in regions with extreme-climate biomes -It is highest along seacoasts and rivers. -At more local scales, we cluster together in cities and towns. -This uneven distribution means that certain areas bear more environmental impact than others. -At the same time, some areas with low population density are sensitive and thus especially vulnerable to impact. -Deserts and arid grasslands, for instance, are easily degraded by development that commandeers too much water.

How did China's one child policy affect the work force?

-produced a population with a shrinking labor force, increasing numbers of older people, and too few women. -The shrinking workforce caused by the one-child policy may now slow the growth of the thriving Chinese economy it helped to produce. -Many employers in China are struggling to find workers and must pay wages up to 35% higher than they did a few years ago to keep their employees. -Although this is a welcome development for workers, it threatens China's ability to produce goods as cheaply as it once did, which may induce companies to relocate from China to other nations where labor costs are lower.

demographic fatigue

-some developing nations may already be suffering too much from the impacts of large populations to replicate the developed world's transition, a phenomenon called demographic fatigue. -Demographically fatigued governments face overwhelming challenges related to population growth, including educating and employing swelling ranks of young people. -When these stresses are coupled with large-scale environmental degradation or disease epidemics, the society may never complete the demographic transition.

life expectancy

-the average number of years that an individual in a particular age group is likely to continue to live, but often people use this term to refer to the average number of years a person can expect to live from birth. -Much of the increase in life expectancy is due to reduced rates of infant mortality. -Societies going through these changes are generally those that have undergone urbanization and industrialization and have generated personal wealth for their citizens.

China One Child Policy: 1979

-the government began rewarding one-child families with government jobs and better housing, medical care, and access to schools. -Families with more than one child, meanwhile, were subjected to costly monetary fines, employment discrimination, and social scorn. -The one-child program applied mostly to families in urban areas. Many farmers and ethnic minorities in rural areas were exempted, because success on the farm often depends on having multiple children. -The experiment was a success in slowing population growth: The nation's growth rate is now down to 0.5%, and Chinese women now have only an average of 1.7 children in their lifetimes.

why are age distributions changing in many nations?

-worlds population is aging (baby boom generation is reaching retirement age) -Changing age distributions have caused concerns in some nations that have declining numbers of workers and strong social welfare programs for retirees (which are supported by current workers), such as the Social Security program in the United States.

what is the current world population?

7.8 billion people

Why are some nations still promoting large population growth/have in the past?

=Despite the long-term benefits associated with smaller populations, many policymakers find it difficult to let go of the notion that population growth increases a nation's economic, political, and military strength. =So while China and India struggle to get their population growth under control, some national governments are offering financial and social incentives that encourage their own citizens to have more children. -These incentives include extended maternity and paternity leave, subsidized child care, and tax breaks for larger families.

TFR

One key statistic demographers calculate to examine a population's potential for growth is the total fertility rate (TFR), the average number of children born per woman during her lifetime.

reasons for large population growth

Our spectacular growth in numbers has resulted largely from technological innovations, improved sanitation, better medical care, increased agricultural output, and other factors that have brought down death rates.

how has the Chinese government reinforced gender discrimination (1984)?

The Chinese government reinforced this gender discrimination when, in 1984, it exempted rural peasants from the one-child policy if their first child was a girl but not if the first child was a boy.

percent change formula

new-old / old times 100 -to do annual rate of change: divide by 10 (more of an average, however)

India: population growth

pLots of youth, majority of country is under 25 -Brides have been set on fire by angry in-laws, over dowry and domestic disputes, or failure to produce a son -now Illegal to test what the gender of a fetus is now in India -Larger families do worse, money is more poorly spread out, causing some to move away from larger families