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Chapter 17. Ch. 17 Population. Population by the Numbers. About 2,000 years ago the world’s population was around 300 million Little changed until the Industrial Revolution At the onset of the Industrial Revolution population began to grow 1800 - first billion 1930 - second billion
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Chapter 17 Ch. 17 Population
Population by the Numbers About 2,000 years ago the world’s population was around 300 million Little changed until the Industrial Revolution At the onset of the Industrial Revolution population began to grow 1800 - first billion 1930 - second billion 1962 - 3 billion 1974 - 4 billion 1987 - 5 billion 1999 - 6 billion 2009 - 6.8 billion 2011 – 7 billion
Dynamics of Demography • Demography – scientific study of population; encompasses all measures of population: size, distribution, composition, age structure, and change. • Demography therefore plays a major role in policy formation, planning, and decision making in both the public and private sectors.
Study of Population Trends • The professional demographer considers these events in two ways: • first, by gathering, organizing, and analyzing the patterns of population size, structure, composition, and distribution; • second, by attempting to identify and understand relationships between demographic and social processes.
Study of Population Trends • Three population processes are considered responsible for growth and decline. • Fertility • Mortality • Migration
Measurement of Fertility Fertility measures the number of children born to a woman or population of women. Crude birth rate = (live births x 1,000) total population • This formula is “crude; “ it fails to identify those women in the population most likely to give birth; and it ignores the age structure of the population.
Measurement of Fertility • Fertility rate—the annual number of live births per 1,000 women ages fifteen to forty-four. • Age-specific fertility is the number of live births per 1,000 women in a specific age group. • Total fertility rate—the average number of children born to a woman during her lifetime.
Mortality • Mortality refers to the deaths in a population. • Life span – most advanced age to which human can survive. • Life expectancy – average number of years that persons in a given population born at a particular time can expect to life. • Morbidity – refers to rates of disease and illness in a population.
Measurement of Mortality Crude death rate = (# of deaths x 1,000) total population • Age-specific death rates to measure the number of deaths per 1,000 persons in a specific age group. • Infant mortality rate—the number of deaths among infants under one year of age per 1,000 live births.
Migration • Migration refers to the movement of people from one geographical area to another for the purpose of establishing a new residence; international migration versus internal migrants.
Migration • The gross migration rate is the number of persons per 1,000 members of a population who, in a given year, enter (immigrants) or leave (emigrants) a geographical area. • The net migration rate is the annual increase or decrease per 1,000 members of a population resulting from movement into and out of the population.
Migration • Why do people migrate? • Push–pull theory - people move either because they are attracted elsewhere or because they feel impelled to leave their present location.
World Population Growth • The world’s population is growing at a rate of 83 million people per year, as a result of high birth rate in poorer countries and low death rates in developing countries. • The growth and the distribution of the world’s population—almost 7 billion—vary greatly among the nations of the world.
The Low-Growth North North America and Western Europe Zero population growth-level of reproduction that maintains population at a steady state High cost of raising children Contraceptives Delayed marriage Both partners in labor force High income countries losing population
The High-Growth South Population growth is a major problem for poor nations High birth rates and declining death rates Account for 80% of the planet’s people Culture and the status of women
Malthusian Perspective • Population, if left unchecked, will tend to exceed the food supply. • Checks on population can be positive (famines, wars) or preventive (birth control). • For the poor, any improvement in income is lost to additional births. • The wealthy and better educated already exercise preventive checks.
Raising people’s aspirations for a higher standard of living enhances the beneficial effects of universal education on population control. • A society could accomplish this by raising wages above the minimum required for subsistence, thus providing the poor an opportunity to choose between more children at a minimal standard of living or smaller families with a higher quality of life.
Neo-Malthusians • The neo-Malthusians modified Malthus’s propositions in an attempt to explain the current world situation and to predict possible futures. • Neo-Malthusians note that the development of reliable contraceptives has not distorted marital relations as Malthus feared that it might.
Neo-Malthusians • Historical developments since Malthus’s time indicate that values promoting, and norms supporting, smaller families are positively related to certain kinds of social and economic changes. • Neo-Malthusians argue that many nations have a rate of population growth that overloads this self-regulating process because population growth is excessive to the extent that resources are diverted from socioeconomic change to population maintenance.
Demographic Transition Theory: Four Stages • Demographic transition – the process by which a population, as a result of economic development, gradually moves from high birth rates and death rates to low birth rates and death rates.
Population Control • Population control is the conscious attempt to regulate population size through national birth control programs. • Historically, many societies were more concerned with increasing their population size than with overpopulation. • Voluntary population control is generally known as family planning—making it technically possible for women to choose the number of children they will have.
Future World Population Growth • After more than 200 years of acceleration, the annual population growth rate is declining. • The current growth rate of 1.2 percent compares favorably with the peak of 2.04 percent in the late 1960s. • Moreover, the rate is projected to drop to zero by the end of the twenty-first century.
Future Population Growth • Demographers are unsure of future world population growth in part because they do not know for sure how many children today’s youth will have, nor do they know what will happen to change life expectancy, particularly in developing countries. • In developed countries, fertility rates are at or below two children per couple • In developing societies, women average four children each.
What is the future of world population growth? • The United Nations offers three possible world population growth scenarios, varying depending on their assumptions regarding the average number of children women will bear. • Medium Scenario: women will have to average two children, world population will rise to more than 9 billion by 2100, depicts zero population growth—when deaths are balanced by births so that the population does not grow.
What is the future of world population growth? • The time lag is what demographers call population momentum—a population continues to grow, regardless of a recent drop in the birth rate, because of the existing population base created by past growth.
Population Growth in the United States and Other More Developed Countries: 1950-2050
Population Growth in the U.S. • The population of the United States will continue growing despite the average American family reproducing at the replacement level of 2.0 children per family. • The U.S. population experienced natural increase (excess of births over deaths) each decade of the twentieth century. • Demographers often use the total fertility rate (the average number of children born to a woman during her lifetime) to predict population change.
