POPULATION
Population-total number of people occupying a given area.
Population distribution-the way people are spread out on the
land.
Population density-number of persons per unit area= number of
people in a given area/total area of the place=XP/km2.
Demography-study of statistical data on human populations.
Sources of Population Data
Primary sources- registration of births and deaths and censuses.
Secondary sources-census reports, textbooks, periodicals, etc.
Factors Influencing Population Distribution
Distribution of population on the earth’s surface isn’t uniform due to
the following factors:
Climate
Areas with moderate temperatures and high rainfall have high
population per unit area than those with extremely high or low
temperatures and low unreliable rainfall because moderate
temperatures give comfort to people and abundant rainfall favours
growth of crops.
Relief
High altitude areas have low population because of extremely low
temperatures which doesn’t support growth of crops to ensure food
sufficiency.
Plains and gently sloping areas have higher population than steep
areas due to fertile soils, ease to erect buildings and construction of
transport infrastructure.
Vegetation
Dense forests are sparsely populated because they are habitat to
wild animals and it’s difficult to develop transport.
Grasslands have high population if rainfall is favourable because
they are easy to clear and relatively level or gently sloping.
Soils
Areas with fertile soils and reliable rainfall have high population
because they are agriculturally productive while those with poor
soils e.g. savannah with leached soils have low population since
they are agriculturally unproductive.
Drainage
Well drained areas have high population than swampy areas
because they support settlement and farming.
Areas which are swampy have less population because it’s difficult
to construct buildings, carry out agriculture and also mosquito
infested.
Pests and Diseases
Areas infested with mosquito and tsetse flies have low population
because those pests transmit malaria and sleeping sickness and
Nagana to livestock.
Disease epidemics cause low population in areas affected
Historical Factors
Colonisation caused people to be driven from their homes in to
reserves to create room for white farmers e which caused low
population in indigenous people’s farms while the population in
reserves kept on increasing.
Tribal Conflicts
Areas with tribal conflicts are sparsely populated because people
move away from there to seek safety .
Economic Factors
Towns and areas with mining activities have high population as
people go to seek for jobs
Political Factors
Political unrest may cause people to move from their home area
leaving it sparsely populated .
Government Policy
Government programmes such as construction of dams and mining
may require removal of people from certain areas causing them to
be sparsely populated while the population in areas of destination
increases.
Factors Influencing Population Growth
Population growth is the change that occurs in the number of
people in a population over a given period of time.
Population may grow positively by number of people increasing in
a population or negatively by having a decrease in the number of
people.
The main factors influencing population growth are fertility,
mortality and migration.
Fertility
Fertility-number of live births a woman has during her
reproductive period.
Fecundity-ability of a woman to conceive and give birth to a child
regardless whether alive or still born.
Infecundity/Sterility-inability of a woman to conceive and give
birth to a child regardless whether alive or still born.
Primary Infertility-involuntary childlessness.
Involuntary Secondary Infertility-involuntary childlessness
caused by a second factor e.g. when a woman has had a
child/children and is unable to have more due to health factors.
Voluntary Secondary Infertility-voluntary childlessness where a
woman who has had a child/children decides not to have any more
e.g. by using contraception methods.
Fertility Rate- average number of children that a woman of child
bearing age (15-49 years) will have in her lifetime.
High fertility rate leads to high population growth while low
fertility rates lead to slow or negative population growth.
Population Growth-increase or decrease in the number of people.
1. Natural Population Growth
Natural increase or decrease in population.
It’s calculated using Crude Birth Rate/estimated rate of births
in a population (CBR) and Crude Death Rate/estimated
rate of deaths in a population (CDR).
CBR=total number of births in a year ×1000/total population
estimated at mid year=X births/1000population.
CDR=total number of deaths in a year×1000/total population
estimated at mid-year=X deaths/1000population.
N.P.G=CBR-CDR×100/1000=X%.
For instance, in 1999 the CBR in Kenya was 41.3 while CDR
was 11.7. Therefore the population growth was (41.3-11.7)
×100/1000=29.6%.
2. Numerical population Growth
Actual or absolute increase in the number of people in an area
within a given period of time.
=inter-censal increase×100/total population in the former
census
For instance pop in 1989 was 2000 and in 1999 was 2500.
Inter-censal increase was 500
=500×100/2000=25%.
Causes of High Fertility Rate in zimbabwe
Cultural Beliefs
1. Early marriage of women which lengthens their fertile duration.
2. Belief in large families as a source of prestige e.g. children are a
source of labour and girls are a source of dowry.
3. Polygamy which causes competition between wives leading to
large number of births per woman.
4. Sex preference when there is a high regard for a birth of a son/heir
to ensure continuity of the family status which causes couples who
are bearing girls to continue bearing girls until they get a boy.
5. Naming of relatives whereby couples will continue to get children
until they finish naming relatives of both sides e.g. fathers,
mothers, uncles, aunts, etc.
Other Factors
1. modernisation which leads to decline in social values leading to
free interaction of young girls and men causing girls to become
mothers at tender age.
2. Availability of enough and better food ensuring people are healthy
and live longer and are able to bear more children as they are able
to feed them.
3. Availability of health services for both mother and child which
provide prenatal and post natal care.
Factors Which Have Caused Low Fertility Rates in
zimbabwe/Slow population Growth
1. Economic considerations where modern families prefer fewer
children because it has become expensive to bring up a child.
2. Increased use of birth control measures.
3. More girls are attending school so they don’t get married early.
4. Education making women to opt to remain single as they get
employed and no longer look to marriage as a source of financial
security.
5. Modern career opportunities which have a limiting influence on the
women’s fertility rate as most employees don’t want women who
keep on going on maternity leave.
Mortality
Mortality refers to deaths among members of a population.
It reduces the population in a given area
It also affects its structure or composition of the population in
terms of age and sex whereby if there is consistent death of a
particular age or sex there will be marked change in the
population because the other ages or sex will be more than the
affected ones.
Causes of Mortality/ More Factors Which Cause Slow Population
Growth
1. Low nutritional standards which cause deficiency diseases
reducing body’s ability to fight diseases which may kill many
children below 5 years.
2. Low hygiene standards which may cause diarrhoeal diseases such
as cholera which kill young and old members of the population.
3. Prevalence of natural calamities e.g. droughts, floods and
earthquakes which also leads to deaths of many.
4. Epidemics and disease outbreaks such as HIV/AIDS which has
eliminated large numbers of people in communities where wife
inheritance is practised and as was the case in S.W. Uganda.
5. Human made calamities such as outbreaks of war and high crime
rates which reduce population.
6. Emigration i.e. movement of people from their country especially
the youth to settle else where which reduces population at the area
of origin.
Causes of Decline in Death Rates in Countries
1. Immunisation of infants which has reduced infant mortality rate.
2. High nutritional standards which have reduced incidents of
deficiency diseases which kill children aged between 1-5 years.
3. Improved hygienic standards which have reduced incidents of
diarrhoeal diseases which used to kill many people.
4. Advanced medical facilities which have ensured availability of
drugs for some diseases which had no drugs which enables people
to live longer.
Demographic/Population Trends
- Various positive or negative changes (transition) which take
place in the population of a given society, country or the world
and their impact on social economic environment.
- Demographic transition refers to the historical change in birth
and death rates from high to low which causes population in-
crease.
Demographic Transition Theory
-A theory compounded to explain this phenomenon.
There are 4 demographic transition phases namely:
Stage/phase 1
o High birth rate and high death rate due to inadequate food sup-
ply, wars, diseases and insufficient medical facilities.
o Little or no increase in population
o Was experienced in Europe before 19th Century.
Stage 2
o High birth rate and a decline in death rate due to improved food
supplies and medical facilities.
o High population growth rate
o Was experienced by European countries in the 19th Century dur-
ing industrial revolution.
Stage 3
-Relatively low death rates and declining birth rate due family
realisation of the need to have small families due to pressure exerted
on economic resour-ces and social facilities, level of education
attainment leading to use of birth control measures.
-Moderate population growth rate.
Stage 4
o Low birth and death rates.
o Low population growth rate.
o The population becomes static and can only reproduce to re-
place the dying ones (population replacement level).
o It’s experienced in industrialised countries like Germany and
Sweden where death rate is falling below death rate.
Population Structure
-Composition of a given population in terms of age and sex.
The information on population structure is obtained in a census and
presented using an age sex pyramid.
Characteristics of an Age Sex Pyramid
o Vertical axis represents age ranges
o Horizontal axis represents percentage of total population
o Right hand side represents females proportion
o Left hand side represents males proportion
Population Structure of a Developed Country
o It’s broad at the base due to factors contributing to high fertility
rates already discussed.
o Hollows for ages 5-9 due to high mortality rate.
o Thins towards the top due to the low life expectancy (average
number of years a person is expected to live) as few people sur-
vive to 70 years.
o Tapers towards the top due to relatively high death rates
throughout age groups.
Population Structure of a Developed Country
o Narrow at the base due to low birth rates causing low population
of children and young people.
o Broadens towards the top due to high life expectancy leading to
a high population of old people (ageing population).
o Broadens towards the top which is an indication of low mortal-
ity rate throughout age groups.
Significance of Population Structure
1. For planning by enabling the government to know the percentage
of available funds to allocate for various sectors e.g. if most of the
people in the population are youth it will allocate more funds for
education and health services and if most are elderly more funds
will be allocated for health and social welfare.
2. For calculation of dependency ratio (proportion of population
which isn’t involved in production activities to the one that is.
DR=children <15+old people/working population (15-64)
o High dependency ratio means the population is strained since
population will devote most of its resources to consumption
instead of investment.
3. For calculation of sex ratio (number of males per 100 females.
o If greater than 100 it means there are a greater number of
males than females which is typical in urban areas.
o Small sex ratio results in male deficiency which affects fertil-
ity which is typical in urban areas.
Consequence of Population Structure
1. Strain on budget due to developing countries having a large popu-
lation of young people whose health and education cost is high and
developing countries having a large proportion of old people whose
cost of health and social welfare is high.
2. Low quality of education and health care in developing countries
due high population leading to the high cost of those services.
3. Better quality of health and education in developing countries due
low population.
4. Strain on working population in developing countries since most of
the money is consumed leaving less for investment. Large popula-
tion of old people does the same in developing countries.
5. Boost in food production when there is a large proportion of males
due to the availability of a large labour force.
6. Heavy taxation of the working population when the dependency of
young and old is high in order to avail funds for provision of social
amenities.
7. Large number of females than males leads to low birth rates and
consequently slow growth of population.
8. Increase in promiscuity when there are a large number of females
than males.
Consequences of Population Growth
Overpopulation (Positive Population Increase)
Positive Effects
1. A large population provides cheap labour due to a large number of
people competing for jobs.
2. Increased exploitation of natural resources and industrial develop-
ment due to increased demand for goods and services causing those
activities to be increased to meet the demand.
3. Technological innovation due to pressing needs associated with a
high population (necessity is the mother of invention).
Negative Effects
1. Pressure on land leading to land fragmentation.
2. Environmental degradation when people clear forests to make
room for settlement and agriculture.
3. Low investment and slow growth of industry as the government
spends a lot of money on education and medical facilities leaving
less for investment.
4. Lowering GDP (aggregate value of goods and services that a coun-
try can produce) due to inability to save any money for investment.
5. High rate of unemployment due to employment sector growing at a
slower rate than population growth.
6. Towns face problems of water shortage, pressure on social amenit-
ies and high cost of housing leading to development of informal
settlements such as slums which expand covering agricultural land
surrounding the towns.
Under population (Negative/Slow Population Growth)
-This is the case in developed countries.
1. High government spending on health and social welfare as the pop-
ulation consists of a high proportion of old people due top low
birth rates and low death rates.
2. High cost of production since there is a small work force consisting
of skilled people whose wages are high.
3. Underutilisation of resources such as agriculture and mineral re-
sources since there is shortage of labour due to sparse population
and most of it being concentrated in urban areas.
4. Inadequate market for goods and services due to a small popula-
tion.
5. Underdevelopment and low living standards in rural areas since a
large percentage of people live in urban areas.
6. Traffic congestion and atmospheric and noise pollution in urban
areas due to continuous expansion of towns.
7. Reduced food production as towns expand and engulf surrounding
agricultural land.
