Chapter 8: Human population
8.1 population growth:
Like other populations, human may grow and increase in numbers in case of no limitations.
Population growth can be represented in graphs, showing increasing of population through the time.
S or sigma shape graphs are used for illustration, which is divided into main regions:
1. lag phase: the period of time in population growth when an organism is adapting to its new
environment and the growth is slow.
2. log phase: when the growth rate of a population increases overtime as all requirements are in
superabundance, and reaches the peak.
3. Stationary phase: when the growth rate of a population has slowed down to zero as the carrying
capacity is reached.
Carrying capacity: the maximum size of a population that an environment can support in terms of food,
water and other resources.
8.2 change in population size
Birth rate, death rate and natural increasing:
Birth rate: the number of live births per thousand of population per year.
Death rate: the number of deaths per thousand of population per year.
Natural increase: the difference between birth rate and death rate.
Factors affect birth rate:
-High fertility rate (number of birth for each woman).
-In farming economies of many LEDCs, more people are needed for manual labor families tend to be larger.
-In MEDCs, it is expensive to have children and pensions.
-Many social and political factors result in low use of birth control in LEDCs, whereas in MEDCs birth
control is widely used.
- Many women receive little education and marry young at early age.
Death rate mainly depends on health and medical care.
Not only birth rate and death rate control human population size, migration is also affecting.
Mr. Huzyfa Ahmed
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