HGG1002GEOGRAPHY OF THE HUMAN ENVIRONMENT:

Population systems : Age Distribution

AGE SEX PYRAMID

DEF : This is a graphical illustration that outlines the most important demographic characteristics of population which is the age sex structure.

It also breaks down the country's or locations population into male and female genders and age ranges.

D.T.M.

Relationship between DTM and Age-Sex Pyramids of the population

Features :1.Consists of two sides, • The left side representing male population ,• The right side representing female population

2.The pyramid starts from 0(O), it extends both directions to the left and to the right respectively increasing in size or the proportion of the population.

3. Along the vertical axis the pyramids display five year age increment from birth at the bottom to old age at the top

Stage 1: High Birth rates and High Death rates.

High birth rates

• No birth control or family planning• Many children die in infancy• Many children born so as to labour for the family.• Children are regarded as a sign of virility• Religious beliefs encourage large families

High death rates

• Diseases and plagues (bubonic , cholera , kwashiorkor)• Famine , uncertain food supplies and poor diet• War • Poor hygiene no piped water , clean water and no sewage disposal• Little medical science , high doctor patient ratio.• Competition for food

For example:

Least economically developed countries today: Somalia, and Britain in the 18th century

Stage 2: Birth rates remain high but Death rates fall rapidly

For example:

Britain in the 19th century, Bangladesh , Nigeria

The fall on death rates results from :

• Improved medical care – vaccinations , hospitals, doctors, new drugs and scientific inventions.

• Improved sanitation• Improvements in food supplies • A decrease in child mortality.

Stage 3: Fall in both Birth rates and Death rates.

Usually as a result of :• Improved economic conditions• An increase in women status • Access to contraception• Increased mechanization reducing need for workers• Increased standards of living For example :

China, Brazil and Britain in

the late 19 th century

Stage 4 : Low fluctuating ,Low Birth rate and Low Birth rate Due to • Political stability• Changes in personal lifestyles• More women are in the workforce therefore less couples are having

kids Fro example:

USA , Britain,

Sweden Japan

Stage 5? : declining population Theoretical Death rate exceeds birth rates Negative NIR (natural increase rate : crude birth rate – crude death rate)Mostly eastern European countries are projected so : Russia, Belarus Germany Italy Japan .Most developed are predicted to experience population decline • Factor of more elderly than young population in these countries• Fewer young women who will be entering their child bearing years• Elderly support ratio- the number of working age people (15-64)

divided by the number of persons 65 or older.

Factor affecting the population pyramids.

• Fertility• Birth rate• Death rate • Migration (immigration and emigration)• Disease out breaks• Natural disasters

Presentation done by : T. BERE – R164423S T. SAMANYANGA – R164540T T. MANGOSHO – R164538X K.K. SADZAUCHI – R164430Z M. MAFUMO – R164539K J.J. MUKWEWA – R164525J M.T. TSEKENI – R164424L N. NYANDORO – R165832R T. MADONDO – R165526Y A. NYONI – R164522S

THE END