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Chapter8
Human Population
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Human population:
A population consists of all the organisms of a given species that live in a
particular area.
Population density: population per area (
Population distribution: how the population is spread over an area.
Example: very few or no people live in deserts and mountains, whereas
populations are very high in coastal areas due to availability of fresh water
Sigmoid growth curve.
What is the growth curve of population?

The growth curve of population is a theory that attempts to describe and
explain how and why the number of living things in a given area or
habitat changes overtime e.g. bacteria
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
According to the theory, all populations of living things follow a sigmoid
or ‘S’- shaped graph curve, which consists of five stages:
1. Lag phase
2. Log phase
3. S- phase
4. Stable phase
5. Decline phase
1- Lag phase – Population growth begins slowly from a few
individuals (organisms adapting the environment)
2- Log phase – exponential growth occurs as the number of living
things increases rapidly (the conditions are ideal and maximum
growth rate is reached)
3- S-Phase – the population growth rate begins to slow down as the
availability of resources (factors such as food, water and space)
become limited
4- Stable phase – the carrying capacity for the population has been
reached and the population number becomes stable
5- Decline phase – the population exceeds the carrying capacity of
the environment, leading to overpopulation and a crash in
numbers
Carrying capacity
The carrying capacity is the maximum population size that can be supported by
the resources available in a particular environment
Birth rate: The average number of live births in the world per 1000 people
Death rate: The average number of deaths in the world’s population
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Natural increase
The greater the difference between birth rate and death rate, the faster the
population grows
Factors effecting birth rate:
In LEDCS
 More people are needed for labour
 High death rate for the very young (high infant mortality), birth rates are
also high.
 low use of birth control in LEDCs
 parents tend to have many children to take care of them in their old age
In MEDCS
 it is expensive to have children
 Pensions are provided by the state they do not need children to take care
of them in their old age.
 In MEDCs birth control is widely used
Population/age pyramid: a diagram that shows the proportion of the
population that is male and female in different age groups (usually 5-year
interval)
Expanding (young) populations (LEDC 2015):
 A wide base because of a high birth rate and many children being
born each year
 A large proportion of young dependents aged 0-5 years as a result
of the high birth rate
 An even decline in shape up the age groups as the deaths rate is
high at all ages
 A narrow, short, top with few people living into old age because
life expectancy is low
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Stationary populations (MEDC 2016):


Population that is almost stationary, with a rectangular shape, except at
the top
A stable proportion of young dependents aged 0-5 years as a result of
the low birth rate

A shape of straight sides up the age groups as the death rate is low at all
ages

A tall, wide, top with many living to old age because life expectancy is
high
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Contracting (old) populations (LEDC 2016):

A narrow base because of a low birth rate and few children being born
each year

A low proportion of young dependents aged 0-5 years as a result of the
low birth rate

A shape of straight sides up the age groups as the death rate is low at all
ages

A tall, wide, top with many living to old age because life expectancy is
high
• Dependent population:
Those people in the population who are not economically active (working) i.e.
the young (<16) and old (65+) and thus rely on those who are working for their
needs.
• Independent population:
Those people in the population who are economically active (working) i.e. the
middle-aged (between 17 and 65).
• Taxes from the independent population is used for:
 Education for the youngsters and provision of school places for the
children yet to reach school age.
 Creating care-home places and hospitals for the ageing population.
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Migration
This refers to the movement of people from one place to another, and in
particular, immigration (people moving into the country) and emigration
(people moving out)
At the end of a year, the following calculation is made to see whether the
number of people in a country has increased or fallen:
Population growth (birth rate + immigration) – (death rate + emigration)
Why do people migrate?
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Managing human population size
Strategies for managing population growth:

provision of, family planning services or contraception (availability of
contraceptives)

birth control programmes

improved, health services or childcare

Public education (including on family planning) or literacy

educating women (so women have, careers or children later)

national policies or laws (antinatalist) to reduce, birth or fertility rate e.g.
China

national policies or laws (pronatalist) to increase, birth or fertility rate
e.g. France

control borders or migration
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