The Dynamics of Demography is the scientific study

The Dynamics of Demography is the scientific study of population. l Sociologists study population because it affects social structure, especially in crowded areas. l The collection of population data is very important because of its use by government and industry. l Sociologists look for patterns that will help them understand predict how groups of people will behave. 1

How do sociologists define population? A population is a group of people living in a particular place at a specified time. l To study population, demographers look at many factors, including size, distribution, composition, and structure. l Demographers analyze three processes: birth, death, and migration. 2

How is fertility measured? Fertility is measured in several ways. l The crude birth rate is the annual number of live births per one thousand members of a population. l The fertility rate is the annual number of live births per one thousand women aged fifteen to forty-four. l The total fertility rate is the average number of children born to a woman during her lifetime. 3

Mortality refers to the number of deaths within a population. l Sociologists analyze mortality by examining life span and life expectancy. l Sociologists measure mortality by analyzing the crude death rate and the infant mortality rate. 4

Migration refers to the movement of people. l It can occur within a country or between countries. l Sociologists measure migration using the gross migration rate or net migration rate. 5

World Population World population growth exhibits certain patterns. l Countries measure the number of people in a population by taking a census. l The world’s population continues to grow at a rapid rate, since the doubling time is getting shorter. 6

Malthus and Population Growth In 1798, Thomas Robert Malthus, an English minister and economist, published An Essay on the Principle of Population. He described relationships between population growth and economic development. l Population, if left unchecked, will exceed the food supply. l Checks on population can be positive (increase mortality) or preventative (decrease fertility). l For the poor, any improvement in income is eaten up in additional births. 7 l The wealthy and well-educated already exercise preventive checks.

The Demographic Transition The demographic transition theory states that population growth is a function of the level of economic development in a country. l This theory takes into account agricultural productivity and reliable methods of birth control. l Demographic transition theory describes four stages of population growth. 8

Future World Population Growth World population growth has reached a turning point. After more than two hundred years of increase, the annual population growth rate is declining. Despite this decline, world population will continue to grow until the middle of the twenty-first century. l Zero population growth will occur when deaths are balanced by births so that the population does not increase. l Population momentum is the inability to stop population growth immediately due to a previous high rate of growth. 9

Future World Population Growth l The replacement level is the rate at which people replace themselves without adding to the population. 10

Population Control Population control is the conscious attempt to regulate population size through national birth control programs. l By 1990, most countries had in place formal programs to reduce birth rates. l The voluntary use of population control methods is generally known as family planning, and it has a mixed success rate. l Compulsory methods of family planning have been instituted by some governments and achieved high success rates. 11

Population Pyramids Population pyramids are a graphic depiction of the age and sex composition of a population. l Age and sex are key indexes of fertility and mortality rates. l Population pyramids illustrate the dependency ratio that relates the number of dependent persons and economically active persons. 12

The Urban Transition l The first preindustrial cities developed in fertile areas where surplus food could be grown. l With the Industrial Revolution came a major increase in the rate of urbanization. l The development of factories was an especially important influence on the location of cities. l Urbanization in developed and developing nations has occurred at different speeds. l The United States is now primarily a suburban nation. 13

Urbanization l A city is a dense and permanent concentration of people living in a limited geographic area who earn their living primarily through nonagricultural activities. l The world has been greatly changed by urbanization–the process by which an increasingly larger portion of the world’s population lives in or very near to cities. 14

World Urbanization is a worldwide movement. Nearly 45 percent of the world’s population now lives in urban areas. l Developed and developing countries have distinctly different patterns of urbanization. l The number and size of cities differs between developed and developing nations. 15

Suburbanization in the United States Suburbanization occurs when central cities lose population to the surrounding areas. l The United States is now predominantly suburban. l Since 1950, the proportion of the population living in suburbs has more than doubled. l Technological developments have caused suburbanization. l Cultural and economic pressures have also encouraged the development of suburbs. 16

What is the central city dilemma? The central-city dilemma is the concentration of a large population in need of public services without the tax base to provide them. l Businesses followed the more affluent people to the suburbs because of lower tax rates, less expensive land, less congestion, and a new customer base. l One solution to the central-city dilemma is gentrification–the restoration of parts of inner cities. 17

What are edge cities? An edge city is a suburban unit specializing in a particular economic activity. It is a small, morefocused version of an urban downtown. l Employment may focus on a particular industry, such as computer technology, finance, or health care. l Edge cities offer a full range of services. l Edge cities are not separated from the larger urban area by legal and physical boundaries. 18

Urban Ecology Urban ecology is the study of the relationships between humans and their city environments. l Although every city is unique, patterns have been found in the way humans interact with the cities they inhabit. l Urban ecologists have developed four major theories of city growth: concentric zone theory, sector theory, multiple nuclei theory, and peripheral theory. 19 Click the hyperlink to view more information about the major theories of city growth or click the right arrow to proceed through the presentation.

Concentric Zone Theory Concentric zone theory describes city growth in terms of distinctive zones that develop from the central city outward in a circular pattern. l The central business district is the innermost circle and the heart of the city. l The zone in transition is the zone that surrounds the central business district. l The three zones that surround the central business in consecutive order are the zone of workingmen’s homes, a residential zone, and the commuters’ zone. 20

Sector Theory Sociologist Homer Hoyt advocated the sector theory that said growth patterns are strongly affected by major transportation routes. l Sectors tend to be pie-shaped, with wedges radiating from the central business district to the city’s outskirts. l Some sectors will be predominantly industrial, others will contain stores and professional offices, others will be “neon strips” with motels and fastfood restaurants, and still others will be residential sectors, each with its own social class and ethnic composition. 21

Multiple Nuclei Theory Chauncy Harris and Edward Ullman suggested that cities do not always follow a pattern dependent on a central district, and they developed the multiple nuclei theory. l The multiple nuclei theory states that a city may have several separate centers, some devoted to manufacturing, some to retail trade, some to residential use, and so on. l These specialized centers can develop because of the availability of automobiles and highways. l They reflect such factors as geography, history, and tradition. 22

Peripheral Theory The peripheral theory emphasizes the growth of suburbs around the central city. l Many cities today no longer have a central city core to which other parts of the metropolitan area are oriented all of the time. l Dependence on shipping, railroads, and heavy manufacturing has been replaced by more flexible means of transportation, such as cars and trucks, and large urban areas are now encircled by highways. l New technologies are also loosening the ties of most parts of the city to the central city core. 23