Birth, Death, and Migration
C HAPTER 15
B IRTH , DEATH A,DND M IGRATION
I. Why Focus on Extreme Cases?
A. Births, deaths, and migration are key experiences, not just for individuals but
also for societies.
B. Generally, being at the extreme ends of an experience suggests vulnerability
and sometimes special advantage.
II. The Study of Population
A. Core Concept 1: Demography, a subspecialty within sociology, focuses on
births, deaths, and migration – major factors that determine population
size and rate of growth.
1. Demography - a subspecialty within sociology that focuses on the
study of human populations, with particular emphasis on population
size and rate of growth
B. Births add new people to a population.
1. Each year, the world adds approximately 134 million people.
2. For comparative purposes, demographers often convert the number of
births into a rate known as the crude birth rate—the annual number of
births per 1,000 people in a designated area.
a. The age-specific birth rates - the birth rate for a specific age group
within the population; for example, the birth rate among women
of childbearing age (15-54 years old)
b. The total fertility rate - states the average number of children that
women in a specific population bear over their lifetimes
C. Deaths reduce the size of a population.
1. Each year, the planet loses about 56.2 million people to death.
2. This loss is often expressed as a rate: the crude death rate - the annual
number of deaths per 1,000 people in a designated area
3. The death rate among those 1 year old or younger is called the infant
4. Maternal mortality rate is the death of a woman while pregnant or
within 42 days of a termination of pregnancy from any cause related to
or aggravated by pregnancy or the way it is managed.
D. Migration is the movement of people from one residence to another.
1. In-migration is the movement of people into a designated area and out-
migration is the movement of people out of a designated area.
2. Net migration is the difference between the number moving into an
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area and the number moving out.
a. Migration is a product of two factors.
i. Push factors are the conditions that encourage people to move
out of an area. Common push factors are religious or political
persecution, discrimination, depletion of natural resources, lack
of employment opportunities, and natural disasters.
ii. Pull factors are the conditions that encourage people to move
into a particular area. Common pull factors are employment
opportunities, favorable climate, and tolerance.
3. International Migration - the movement of people between countries
a. Emigration - the departure of individuals from one country
b. Immigration - the entrance of individuals into a new country
c. Most governments restrict the numbers of foreign people who are
allowed to enter. Sometimes governments encourage the
immigration of certain categories of people to fill occupations
characterized by a shortage of workers.
4. Internal migration involves movement within the boundaries of a
single country—from one state, region, or city within a country to
E. Population Growth
1. The population size of a geographic area constantly changes
depending on births, deaths, and migration flows.
2. Demographers calculate annual growth in population size according to
the following formula: (Number of births – number of deaths) +
(immigration – out-migration).
3. Doubling time - the estimated number of years required for a country’s
population to double in size. Note: the world’s population has doubled
five times in the last 2,000 years.
III. Age-Sex Composition
A. Core Concept 2: The age-sex composition of a population helps
demographers predict birth, death, and migration rates.
1. Population pyramid - a series of horizontal bar graphs, each of which
represents a different five-year age cohort, commonly depicting a
population’s age and sex composition
a. The population pyramid offers a snapshot of the number of males
and females in the various age cohorts at a particular time.
b. Generally, a country’s population pyramid approximates one of
i. Expansive pyramids are broadest at the base, with each
successive bar smaller than the one below it. The population is
increasing in size and is disproportionately composed of young
ii. Constrictive pyramids - narrower at the base than in the
middle. This shape shows that the population is
disproportionately composed of middle-aged and older people.
iii. Stationary pyramids - similar to constrictive pyramids except
166 Birth, Death, and Migration
that all age cohorts are roughly the same size
IV. The Theory of Demographic Transition
A. Core Concept 3: The demographic transition links the birth and death
rates in Western European countries and the U.S. to the level of
industrialization and economic development.
1. In the 1920s and early 1930s, demographers observed birth and death
rates in various countries.
a. They proclaimed that the characteristics of a country’s birth and
death rates are linked to its level of industrial or economic
b. They hypothesized that the less economically and industrially
developed countries would follow this pattern.
2. All countries have followed or are following the essential pattern of
the demographic transition. They differ with regard to the timing of
the declines and the rates at which their populations increase after
death rates begin to fall.
B. Stage 1: High Birth and Death Rates
1. Stage 1 of the demographic transition is often referred to as the stage
of high potential growth. If something happened to cause the death
rate to decline —for example, improvements in agriculture, sanitation,
or medical care—the population would increase dramatically.
2. In this stage, life is short and brutal. The most vulnerable groups
include women of reproductive age, infants, and children younger than
3. It is believed that women gave birth to large numbers of children and
that the crude birth rate was about 50 per 1,000—the highest rate
recorded and, thus, the highest rate believed possible for humans.
4. If the birth rate had not remained high, the society would have become
5. According to Thomas Malthus, positive checks served to keep
population size in line with the food supply.
a. Positive checks include events that increase death, such as
epidemics of infectious and parasitic disease, war, famine, and
b. Malthus believed that the only moral way to prevent populations
from growing beyond a size that could not be supported by the
food supply was delayed marriage and celibacy.
C. Stage 2: The Transition Stage
1. Around 1650, mortality crises became less frequent in Western
2. By 1750, the death rate had begun to decline slowly in that region.
3. Urbanization accompanied the unprecedented increases in population
D. Stage 3: Low Death Rates and Declining Birth Rates
1. Around 1930, both birth and death rates fell to less than 20 per 1,000.
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2. The remarkable successes in reducing infant, childhood, and maternal
mortality rates permitted accidents, homicides, and suicide to become
the leading causes of death among young people.
3. The reduction in the risk of dying from infectious diseases ensures that
people who would have died of infectious diseases in an earlier era can
survive into middle age and beyond.
4. For the first time in history, people age 50 and older account for more
than 70 percent of the annual deaths.
5. Stage 3 is distinguished by an unprecedented emphasis on
consumption, which is made possible by advances in manufacturing
and food production technologies.
E. Industrialization: An Uneven Experience
1. Core Concept 4: Industrialization was not confined to Western
Europe and the United States. Industrialization pulled people
from across the planet into a worldwide division of labor and
created long-lasting and uneven economic relationships between
2. During the Industrial Revolution, people from even the most
seemingly isolated and remote regions of the planet became part of a
worldwide division of labor.
3. The countries of the world can be classified into two broad categories
in regard to industrialization: developed and developing.
a. Comparable but equally misleading terms used to describe these
dichotomies include industrialized/industrializing and First
b. These names are misleading because they suggest that a country is
either industrialized or not industrialized. The dichotomy implies
that a failure to industrialize is what makes a country poor.
4. The World Bank, the United Nations, and other international
organizations use a number of indicators to distinguish between so-
called developed and developing countries, including doubling time,
infant mortality, total fertility, per capita income, the percent