HUMAN POPULATION

POPULATION GROWTH AND VARIATIONS AMONG NATIONS

​

• About 250 years ago, humanity existed relatively small numbers with limited technologies.
• Any environmental disturbances caused by people were local and usually well with in the environments capacity to absorb them.
• In the last two centuries, developments have occurred that have created environmental problems beyond nature’s assimilative capacity.
• Explosive growth of population creates environmental pressure because of the sheer number of people on earth.

POPULATION :

• A Population is defined as a group of individuals belonging to the same species which lie in a given area at a given time.
• The study of population change is known as

“population dynamics”.

• POPULATION DENSITY :
• It is expressed as the number of individuals of the population per unit area or per unit volume.
• This varies in response to changes in the environment and introduction with other living organism.

PARAMETERS AFFECTING�POPULATION SIZE

• BIRTH RATE OR NATALITY : Number of live birth per 1000 people in a population in a given year.
• DEATH RATE OR MORTALITY : Number of death per 1000 people in a population in a given year.
• IMMIGRATION : Arrival of individuals from

neighbouring population.

• EMIGRATION : Dispersal of individuals from the original population to new areas.

​

POPULATION GROWTH :

• The rapid growth of the globe's population for the past 100 years results from the difference between the rate of birth and death.

​

CHARACTERISTICS OF POPULATION GROWTH:

EXPONENTIAL GROWTH :

• Population growth shows the dramatic increase in global population in the past 160 years.

HUMAN POPULATION GROWTH HISTORICALLY

1. Early Hunter Gatherers
1. Nomadic, with a strong sense of the earth
2. Practiced intentional birth control

​

• Rise of Agriculture
• Necessary for Survival
1. Animals became extinct via predation and altered habitat
2. Humans began to cultivate own food

Agriculture Gives Rise to Cities

• Food produced in country, consumed in city
1. Food wastes are no longer returned to soil
2. Soil becomes less productive
• Waste of populations concentrated in cities
• Population control in medieval societies
• Infanticide
• Plagues

C. Industrialization

• View of children during early phases of industrial growth
1. Valued as cheap source of income and cheap labor
2. Exponential growth of populations
• By 1900s, Birth Rate in Industrialized World Dropped
• Rise in standards of living
• Safe and inexpensive means of birth control introduced
• Increase in the cost of child rearing

REASONS FOR POPULATION GROWTH

​

• Industrial Revolution Infrastructure Water
• Energy
• Transportation
• Increased Productivity
• Nutrition
• Sanitation
• Medicine

​

Maximum Carrying Capacity

The maximum population size that can be supported by environment.

DEMOGRAPHIC TRANSITION

• Movement of a nation from high population growth to low population as it develops economically
• Transition as a result of four stages
• Stage 1—Birth and death rates are both high
• Stage 2—Death rates fall; birth rates remain high; growth rate rises
• Stage 3—Birth rates fall as standard of living rises; growth rate falls
• Stage 4—Growth rate continues to fall to zero or to a negative rate

POPULATION PYRAMIDS

• High Growth: Afghanistan
• Moderate Growth: Mexico
• Zero Growth: U.S.
• Negative Growth: Austria or Italy

​

STAGE 1

• Low birth rates, high (at time erratic) death rates, low growth rates
• stage for much of human history, traditional societies
• practically no country today

STAGE 2

• high birth rates,

declining death rates,

rising growth rates

• improvements in

sanitation (water)

and medicine

• in Europe during Industrial Revolution
• in developing countries since the 50s/60s
• much of Africa today, some countries of Asia (Afghanistan, Nepal, etc.)

STAGE 3

• continued decline of death

rates, declining birth rates,

growth rates decline from

high to lower levels

• change in behavior: adaptation to lower death rate, in particular infant mortality rate
• economic change: urbanization (incentive to have fewer children)
• Mexico today

STAGE 4 & 5

• Stage 4: low birth rates,

low death rates, low

growth rates

• United States today

​

• Stage 5: low birth rates, rising death rates, declining growth rates (if birth rates drop below death rates: negative growth rates)
• several countries of Europe today (Austria)

POPULATION EXPLOSION

• An enormous growth of human beings is called as population.

Causes

• 1. Fertility
• 2. Reduced Infant Mortality Rate
• 3. Increased food production
• 4. Longevity leading to explosion.

IMPACTS OF POPULATION EXPLOSION

• Pollution – increase in cars and emission of greenhouse gases into atmosphere
• Deforestation –to build houses for increasing population
• Freshwater Availability – increase in waste production and contamination of water
• Natural Resources – increase burning of fossil fuels, excessive use of coal
• Global Warming – overall increase in temperature and chances of natural disasters
• Habitat Loss – change in ecosystems affecting tropic levels
• Increase in the level of pollution
• Mass species extinction
• High infant and child mortality
• Increased incidences of HIV and other diseases due to crowding
• Starvation or poor diet, deficiency diseases
• Low birth rate
• Low life expectancy
• Un hygienic living conditions
• High unemployment
• Elevated crime rate
• Conflict over scarce resources
• Overutilization of infrastructure

DEMOGRAPHIC TRAP

• Population Path of Most Less-Developed Countries (LDCs)
• “Trapped” in Stage 2 of Demographic Transition
• Before 1970, LDCs seemed poised to make transition thanks to economic growth
• Since 1970, economic growth has not kept pace with population
• High birth and low death rates result in explosive population growth
• Downward spiral in standard of living

REASONS FOR POPULATION EXPLOSION INDIA…

 Higher fertility rate due to failure of family planning

 Predominating religious or superstitious nature – polygamy, early marriages etc.,

 Importance of male child

 Social insecurity

 Poverty and backwardness

EFFECTS OF POPULATION DECLINE

• As percentage of 60+ aged people increases, population begins decline
• 60+population increase --> severe economic and social problems because 60+ consume
• more medical care
• Social Security
• costly public services
• Labor shortages require automation & immigration

THE GRAYING OF JAPAN

• Family-planning access, cramped housing, expensive land, late marriage, education cost --> voluntary decrease in birth rate
• Low immigration rate
• Health insurance and pension - 45% of national income; could -->low economy
• Illegal immigration bolsters work force

POPULATION PYRAMIDS

WHAT IS A POPULATION PYRAMID?

• It is a diagram that gives information about the proportion of males and females in each age group.
• Also shows:

- proportion of young people (0 -14 )

- proportion of working people (15 – 59)

- proportion of elderly people (60+)

Each age-group designation is called a COHORT

TYPES OF POPULATION PYRAMID

1. Triangular-shaped

2. Beehive-shaped Pyramid

3. Rectangular-shaped Pyramid

Shape of pyramids is controlled by

• Births (but mostly CBR!)
• deaths, &
• migrations.

POPULATION PYRAMIDS AND DEMOGRAPHIC STAGES

• characteristics shapes of ‘pyramids’
• wide base (true pyramid)
• wide middle (bulge), somewhat wider base
• urn- or bottle-shaped
• reversed pyramid
• different shapes--different dynamics

​

​

Population Pyramids in Transition

WHAT IS A POPULATION PYRAMID?

Vertical Axis - Age Groups

Horizontal Axis – Percentage / number

Young dependents

Working population

Elderly dependents

HOW TO READ A POPULATION PYRAMID?

• Read the title e.g. country or city or racial group
• Comment on general shape of the pyramid
• Note the proportion of people in various age groups (cohorts)
• Note the sex ratio
• Interpret the data

​

TRIANGULAR-SHAPED PYRAMID�(BROAD-BASED PYRAMID)

BROAD-BASED PYRAMID

Title: India, 2000

Shape: Broad Base - high birth rates

Narrow Top - small elderly pop

- high death rate

Proportion: - Large proportion of young

- high young dependency

ratio

Sex Ratio: Balance pyramid - Balance sex ratio

STOP

• Where is India on the Demographic Transition Model?

Indonesia

2000

Malaysia

2000

Beehive-shaped Pyramid

BEEHIVE-SHAPED PYRAMID

Title: Singapore, 2000

Shape: Rocket-shaped / Narrow Base

– Low Birth Rates, Slow pop growth

Proportion: Large proportion of working

population, 15-59 yr old - large

group of economically active pop

Sex Ratio: Balanced pyramid

Hong Kong

2000

Taiwan

2000

STOP

• Where are Beehive shaped pyramids on the Demographic Transition Model?

Rectangular-shaped Pyramid

RECTANGULAR PYRAMID

Title: Netherlands, 2000

Shape: Rectangular-shaped - Zero Pop Growth

Narrow Base - Low Birth Rates

- Life-expectancy is high e.g. 80+

- Low death rates

Proportion: Bars of equal length - Balance

Proportion

Sex Ratio: Balance pyramid - Balance Sex

Ratio

UK 2000

Netherlands

2000

STOP

• Where are Rectangular Based Pyramids on the Demographic Transition Model?

POPULATION STRUCTURE AND COMPOSITION

• Population pyramids…show age and gender groups. How do MDC’s and LDC’s differ?

​

• 1.) Sex Ratio: # of males per 100 females. In general slightly more males born, but women outlive men
• Eur and NA 95 males: 100 females
• World wide 102 males: 100 females

​

POP STRUCTURE AND COMPOSITION – CONT’D.

• 2.) Age Distribution
• Dependency Ratio: # of people too old or young to work, compared to # of people in productive yrs.
• % of pop under 15 = % over 65 divided by % in between 15-65 multiplied by 100
• Tells you how many dependents for every 100 workers
• Stage 2 countries: ratio is 1:1 (1 worker for every dependent) Dependents are young
• Stage 4 countries ratio is 2:1 (2 workers for every dependent) Dependents are young and old

AGE DISTRIBUTION – CONT’D

• Graying of the pop in MDCs – more than ¼ of all govn’t expenditures in US, Canada, Japan, and W. Eur goes to Social Security, health care, and other programs for the elderly

​

• Baby Boomer Cohort in US (born 1946-1964)…what does this mean for you?

​

• Generation X = 1965-1980

WHAT DO YOU SEE? WHY?

EACH PYRAMID TELLS A STORY ABOUT THE �PAST, PRESENT & FUTURE �OF A COUNTRY & ITS PEOPLE.