Population 2

Demographic transition model
The "Demographic Transition" is a model that describes population change over time.
Once a country moves from one stage to the next, it does not revert to an earlier stage.
Stage 1
Stage 1- High stationary stage (low growth)
-High fertility ( birth)
-High mortality (death)
-Characterizes a variable large, but short term population growth
- Due to agricultural revolution/war and diseases
-No country remains in this stage

Stage 2
Early Expansive stage (high growth)
High fertility and declining mortality
Occurred in the late eighteenth and nineteenth centuries
Result of the industrial revolution (mass production, steam engine)
Countries in Europe and US entered this stage in 1800, but Asia, Africa reached this stage in the 1950s
due to medical revolution –immunization against small pox

Stage 3
late expanding stage (moderate growth)
-With declining fertility Due to changes in social customs-decision to have fewer children
-People begin living in cities to work in offices, shops or factories,
Most countries in Asia are in this stage while most African countries remain in stage 2

Stage 4
Stage 4 -Low Stationary Stage (low growth)
-Low fertility and low mortality and very low growth rate
-Zero population growth
-More women enter into the labor force
-changes in lifestyle, entertainment and leisure
-Most Eastern European countries experience negative natural increase rate

Population structure
Population structure refers to the way in which the population is made up of groups of differing age and sex.
Developing countries have higher birth rates but much higher infant and childhood death rates.
Developed countries at present is characterized by an almost static overall total, but with an ageing population (Uk)

Population composition
This consist of the distribution of the people across age categories and the number of men relative to the number of women

Age and Sex are the most considered aspects of population composition
Other aspects include:
household income level,
marital status,
level of education etc
Age and Sex: Key indicators of Population composition
Age and sex composition are represented by Age-sex pyramid
Age-sex pyramids display the percentage or actual amount of a population broken down by gender and age. The Most important measurement is the Dependency Ratio. , which is the number of people who are too young or too old to work compared to the number of people in their productive years

Age distribution
Three broad age groups are used
0-14years (percentage below age 15)
15-64years ( working group)
65 and above ( dependent)

Sex Ratio
It is the number of males per hundred females in the population
In general slightly more males than females are born, but males have higher death rates
In Europe and North America the ratio of men to female 95:100 ( 95 men for 100 females)
Globally 102 males:100 females
In the US males under 15 exceed females 105:100. women starts out numbering men about age 30 and females comprise 60% of the population above 65.

Population Pyramid
The Shape of a pyramid is determined primarily by the fertility rate in the community
There are three basic types of population pyramid
Types of Population Pyramid
Expansive
Constrictive
Stationary

Expansive population pyramid
Show larger numbers or percentages of the population in the younger age groups. Ex Latin American and many developing countries

Constrictive
CONSTRICTIVE population pyramids display lower numbers or percentages of younger people.
The age-sex distributions of the United States fits into this type of pyramid.

Stationary Pyramid
STATIONARY or near-stationary population pyramids display somewhat equal numbers or percentages for almost all age groups.
European countries, especially Scandinavian ones, tend to fall into this category.

Uses of population pyramids
They show the number of economic dependents being supported in a particular population
They predict changes in the age structure of the population over the next fifty or so years so that plans can be introduced to cope with the predicted changes.

Aging Population????
The number of people who are above 60 years.
It is predicted that by the year 2050, the number of people over 60years will increase by more than 230%.
Population pyramid will become top heavy

US Aging Population
The U.S. population age 65 and over is expected to double in size within the next 25 years.
By 2030, almost 1-out-of-5 Americans (72 million people) will be 65 years or older.
The age group 85 and older is now the fastest growing segment of the U.S. population.

What will be the Challenges of US’s Aging population?
Economics
Social
Political
Challenges
Increase in pension and medical care
Younger adults must provide taxes to carter for the aged ( increased in tax burden on the working population)
Increase retirement age at which benefits will be paid
Production towards goods and materials for young will require dramatic shift to production for the aged

Why Might the world face an over population problem?
Thomas Malthus
He was a British. He published “an essay on the principles of population as it affects the future improvement of society” in 1798
Between 1803-1826, he predicted that Britain’s population growth will be checked by hunger
His Observations:
World population growing faster than food supplies: population growth rate: exponential
Food production growth rate; Arithmetical

Was Malthus right?
Challenges of Malthus’ theory
His concept referred to closed society ( Britain)
Issues of migration and colonization
Technological improvement: increased in acreages, hybrid seeds, fertilizer application
Supporters of Malthus are known as Neo-Malthusian
How can we account for Switzerland and Japan? Few resources ( less land) but highly developed