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Ch. 15
Populations, Cities, and the
Environment
Chapter 17
Population by the Numbers
 About 2,000 years ago the world’s population was around 300
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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; the study of the size, composition,
distribution, and changes in human population.
 Three basic demographic variables are crucial to
understanding population dynamics.
 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.
Fertility rates: the average number of births per 1,000 people in
the population
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 fortyfour.
 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.
Mortality rates: the average number of deaths per 1,000 people in the population
 A related concept is infant mortality rates—the average number of deaths per
1,000 live births.
 Also related is life expectancy—the average age to which a person can expect to
live.
 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.
Global Life Expectancy at Birth, 2013
© 2016 W. W. Norton & Co., Inc.
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 movement of people from one
geographic area to another for the purpose of resettling
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.
Theories of Population Change
 Robert Malthus was concerned about population growth and
overpopulation.
 The Malthusian theorem states that exponential population
growth would outpace arithmetic growth in food production
and other resources.
World Population Growth over 2,000 Years
© 2016 W. W. Norton & Co., Inc.
Theories of Population Change
(cont'd)
 Neo-Malthusians believe that population growth will eventually
outpace available resources, leading to a global catastrophe.
 Anti-Malthusians believe that family planning (contraception
or any other method of controlling family size and birth of
children) and other changes will eventually cause population
shrinkage.
Theories of Population Change
(cont'd)
 Demographic transition: a theory suggesting the possible
transition over time from high birth and death rates to low
birth and death rates, resulting in a stabilized population
 Anti-Malthusians forecast a very different future when
demographic transition, now occurring in many
industrialized nations, spreads to the rest of the developing
world.
Cities
 Urbanization refers to the movement of increasing
numbers of people from rural areas to urban areas.
Percent Population Residing in Urban
Areas by County, 2010
Cities (cont’d)
 A metropolis is an urban area with a large population,
usually 500,000 to 1,000,000 people.
 A megalopolis (or megacity) is a group of densely populated
metropolises that grow dependent on each other and
eventually combine to form a huge urban complex.
Urbanization (cont'd)
 Suburbanization is the shift of large segments of population
away from the urban core and toward the edge of cities.
 Urban sprawl is a derogatory term applied to the expansion
of urban or suburban boundaries, associated with
irresponsible or poorly planned development.
Cities (cont’d)
 Another trend that has changed many formerly blighted cities
is gentrification —the transformation of poor inner-city
neighborhoods into more affluent, middle-class
communities.
Cities (cont'd)
 Many sociologists also believe that the freedom of city life is a
source of alienation.
 Alienation: decreasing importance of social ties and
community and the corresponding increase in impersonal
associations and instrumental logic
Cities (cont’d)
 Bystander effect: the social
dynamic that shows that the more
people are present in a moment of
crisis, the less likely any one of
them is to take action)
The Environment
 The environment refers to the natural world, the human-
made environment, and the interaction between the two.
Environmental Problems
 Sociologists are interested in how human populations impact
the natural world, especially as environmental degradation
has increasingly become a social problem.
Environmental Sociology
 Environmental sociology: the study of the interaction
between society and the natural environment, including the
social causes and consequences of environmental problems
 Environmental sociology focuses on four areas:
1.
2.
3.
4.
how the political economy influences the environment
society’s attitudes about the environment
the environmental movement (an organized, social
movement)
sustainable development
Environmental Sociology (cont'd)
 The environmental movement is a social movement
organized around concerns about the relationship between
humans and the environment.
 Its first efforts, in the nineteenth century, (conservation era)
focused on conservation of wilderness areas.
Environmental Sociology (cont’d)
 The modern environmental movement arose in the mid-
twentieth century in response to ecological disasters that
threaten public health and safety.
 Mainstream environmentalism grew in the 1980s as the
movement consolidated and lobbied government about
environmental concerns.
Environmental Sociology (cont’d)
 Most recently, grassroots environmentalism has emerged
in response to perceived blind spots in the larger mainstream
groups. Grassroots organizers focus on local action and
community involvement.
Malthusian Perspective
1. Population, if left unchecked, will tend to exceed
the food supply.
2. Checks on population can be positive (famines,
wars) or preventive (birth control).
3. For the poor, any improvement in income is lost
to additional births.
4. 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 selfregulating process because population growth is
excessive to the extent that resources are diverted
from socioeconomic change to population
maintenance.
Projected Population of the United States
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.
The World’s Population Explosion
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.