POPULATION CHANGEChapter 16, Section 1

MEASURING POPULATION

Population= # of people living in a given area at a time. Demography= the area of sociology that

focuses on studying human populations.

Three factors affecting a region’s population: Birthrate Death rate Rate of migration

Help determine how populations change over time.

BIRTHRATE

Birthrate= births within a population Live births/total population x 1,000 Gives the number of births per 1,000

individuals.

Fertility vs. fecundity Fertility # of births that actually occurred

by women of childbearing age. Fecundity measures those ABLE to have

children Affected by various social, economic and health

factors.

DEATH RATE

Mortality= number of deaths within a society. Death rate: Deaths/total population x 1,000

Death rates do not present an accurate picture of a country’s conditions… so, sociologists also use two other factors: infant mortality rate and life expectancy. Infant mortality rate= deaths among

infants/total live births x 1,000 Life expectancy= average # of years a person

can expect to live. There is a correlation between IMR and life

expectancy. This helps determine the overall ‘health’ of a country.

MIGRATION RATE

Demographers also have to take into account the migration of individuals when determining a country’s population.

Factors affecting migration: Push factors religious or political

persecution; famine; discrimination; overpopulation

Pull factors additional freedoms; economic opportunities; higher standards of living

Migration rate= annual difference between in-migration and out-migration.

GROWTH RATE

The three variables affect the size of a population.

Rate at which a population is increasing= growth rate. Birthrate – death rate = growth rate.

Doubling time= amount of time it takes the pop’n to double in size.

Negative vs. positive growth rates… is the population growing or shrinking? Practice calculating country growth rates. - http://www.os-connect.com/pop/p3n.asp

BR DR

GROWTH RATE– ANSWERS

Brazil: 11.43 (population is growing) Population grew 11%

China: 5.26 (population is growing) Population grew 5%

Denmark: .09 (population is growing) Population grew .09%

Which population is growing the fastest?

STUDYING A POPULATION

To examine the composition of a country’s population, demographers (individuals who study population) look at population pyramids (also known as age-sex graphs). Breakdown of population male/female Percentage of the population each age group

comprises Connect events to changes in population Make assessments about overall health Determine whether pop’n is growing or shrinking

EXPLAINING POPULATION CHANGE

Thomas Robert Malthus Malthusian Theory= population increases

in a multiplicative fashion, whereas food supply only grows in an arithmetic progression. Basically… The population is growing too

rapidly for the food supply to keep up.

Malthus proposed ‘checks’ on population. Preventive checks birth control, sexual self-

control and delayed marriage and childbearing. Positive checks war, disease and famine.

MALTHUS (CONT’D)

But, Malthus could not foresee two coming changes in society…

1) Advancement of agricultural techniques that allowed farmers to produce more on same amount of land

2) Birth control emerges as an effective and widely used method.

DEMOGRAPHIC TRANSITION THEORY Population patterns are tied to a society’s level of

technological development. Three stages of a society’s population.

Stage 1 Preindustrial societies; high birthrate and death

rate. I.e. central African societies

Stage 2 Industrial societies; high birthrates and low death

rates (due to improved conditions) Guatemala and other Latin American countries

Stage 3 Industrial/post-industrial societies; low birthrates

and death rates. North America and Europe

DEMOGRAPHIC TRANSITION THEORY

Stage 4 Low birthrate, low

death rate, and increasing life expectancy. Approaching zero growth

rate= pop’n not growing or shrinking.

Stage 5 Low birthrate (less than

in Stage 4), low death rate, and increasing life expectancy. Population shrinking

CONTROLLING POPULATION GROWTH

Current world’s population: 7,315,737,000* Current U.S. population: 324,827,684*

* as of 10:40 am 5/18/2015

Two main strategies to control the world’s population- family planning and economic improvements

FAMILY PLANNING

Strategy used to lower the birthrate; occurs when couples consciously decide to have a certain number of children. Helps reduce the number of unplanned

pregnancies.

Antinatalism= strict form of family planning involving official policies designed to discourage childbirth. In 1980, China adopted an incentive and

sanction system. Government benefits for those who adhere to

one child policy; large fines and penalties for those that do not.

ECONOMIC IMPROVEMENTS

Better health, higher levels of income and access to education will help lower birthrates.

However, many impoverished countries do not have the resources to provide this economic assistance. Demographers suggest evenly redistributing

wealth within a nation to help reduce poverty.

Encourage limits on family size once basic needs are met.