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Sociology - Population and Urbanization

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    Study Guide Sociology – Population and Urbanization 1. Population and Demographic Variables For most of human history, people preferred large families. This was mainly about survival. High death rates from disease, war, and dangerous living conditions meant that having many children increased the chances that some would survive and carry on the family line. Things changed dramatically in the 20th century. Advances in medicine, technology, and sanitation reduced death rates around the world. As a result, the global population began to grow very quickly — a trend often called the population explosion . Today, the world’s population increases by about 90 million people every year , with most of this growth occurring in poorer countries. Because of this rapid growth, sociologists and demographers are deeply concerned about the future effects on resources, living condi tions, and the environment. 1.1 What Is Demography? Demography comes from a Greek word meaning “description of people.” It is the scientific study of human populations. Demographers focus on: • The size of populations • The composition of populations (such as age and gender) • The movement of people from one place to another They also study how populations grow, shrink, or stay stable — and what societies do to manage population change. Several key demographic variables are especially important:

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    Study Guide • Fertility and fecundity • Mortality and life expectancy • Migration 1.2 Fertility and Fecundity One of the biggest influences on population size is fertility . Fertility refers to the average number of children a woman actually has during her reproductive years, from puberty to menopause. Fertility is often confused with fecundity , but the two are different. • Fecundity means the number of children a woman is biologically capable of having . • Factors such as health, income, access to healthcare, and personal choices strongly affect whether that biological potential is reached. 1.3 Measuring Fertility To measure fertility at the national level, demographers calculate the crude birth rate . This is: • The number of live births per year • For every 1,000 people in the population It is calculated by dividing the number of births in a year by the total population and multiplying by 1,000. These figures usually come from government records, which may be incomplete or inaccurate — especially in developing countries where record - keeping systems may be weak or nonexistent.

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    Study Guide 1.4 Fertility Around the World • The world’s average fertility rate is about 3 children per woman . • The highest fertility rates are found in Africa , at nearly 6 children per woman . • The lowest fertility rates occur in Europe , at about 1.5 children per woman . • In the United States , the fertility rate is around 2 children per woman . Interestingly, while women may be biologically capable of having many children, the average fecundity rate worldwide is about 20 children per woman , showing how social and economic factors limit actual fertility. 1.5 Mortality and Life Expectancy Population size is also affected by mortality , which refers to the number of deaths in a population. 1.6 Crude Death Rate Demographers measure mortality using the crude death rate , which is: • The number of deaths per year • For every 1,000 people in the population This is calculated in the same way as the crude birth rate. In the United States, the crude death rate usually stays around 8 or 9 deaths per 1,000 people . 1.7 Infant Mortality Rate Another important measure is the infant mortality rate , which looks at:

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    Study Guide • The number of deaths of infants under age one • For every 1,000 live births in a year Infant mortality rates in North America are relatively low compared to many other regions. However, differences still exist within societies. For example: • African Americans have an infant mortality rate of about 19 • Whites have a rate of about 8 1.8 Life Expectancy Lower infant mortality is linked to higher life expectancy , which is the average length of life for people in a society. • In the United States, people born today can expect to live into their 70s . • This is about 20 years longer than life expectancy in many low - income countries. 1.9 Migration Another factor that affects population size is migration , or the movement of people from one place to another. Migration can be: • Involuntary , such as when enslaved people were forcibly brought to the Americas • Voluntary , such as families moving from cities to suburbs

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    Study Guide 1.10 Types of Migration • Immigration : moving into a country or region ○ Measured by the immigration rate (number of people entering per 1,000 residents) • Emigration : moving out of a country or region ○ Measured by the emigration rate • Internal migration : movement within a country’s borders 1.11 Population Growth Population growth depends on fertility, mortality, and migration . • Poorer countries usually grow because of high birth rates , often due to limited access to contraception. • Richer countries grow through a combination of natural increase and immigration . Demographers calculate a population’s natural growth rate by subtracting the crude death rate from the crude birth rate. • Low - growth countries tend to be industrialized (such as the U.S. and Europe). • High - growth countries are often less industrialized (such as those in Africa and Latin America). 1.12 Population Composition Demographers are also interested in who makes up a population , not just how big it is. One important measure is the gender ratio (or sex ratio) , which is:

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