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Human pop. and growth rate
· Events that have led to a big increase in pop. size:
- development of agriculture
- development of manufacturing and trade that created the industrial revolution.
Human pop. slowly Increased
increased, but was still exponentially
checked by diseases.
Before 10 000 years ago, Bubonic
disease/ famine produced plague
regular pop. Crashes and
kept numbers fairly
constant.…read more

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Factors affecting growth and size of
human pop.
· Birth rate ( BR) and death rate (DR).
· Migration: individuals move from one pop. to another:
- IMmigration: individuals JOIN a pop. from outside.
- EMigration: individuals LEAVE a pop.
Pop. change ( growth) = ( births + immigration) ­ ( deaths + emigration)
% pop. growth rate ( in given period) =
pop. change during period
--------------------------------------- x 100
pop. at start of period…read more

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Factors affecting birth rates (BR).
· economic conditions - countries with low per capita income =
higher BR.
· cultural and religious backgrounds ­ some countries
encourage larger families and religions opposed to birth
· social pressures and conditions ­ sometimes large family =
better social standing.
· birth control- the extend to which birth control and abortion are
used influence BR a lot.
· political factors ­ governments influence BR through education
and taxation policies ( eg: China's one child policy)
number of births per year
BR = ------------------------------------- x 1000
tot. pop. in same year…read more

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Factors affecting death rates (DR).
· age profile ­ the greater the proportion of elderly in a pop., the higher the DR is
likely to be.
· life expectancy at birth ­ residents of MEDCs ( more economically developed
countries) live longer than those of LEDCs. ( less economically developed
· food supply ­ an adequate and balanced diet reduces DR.
· safe drinking water and safe sanitation ­ reduces DR by reducing risk of
contracting water-borne diseases ( cholera)
· medical care ­ access to healthcare and education reduces DR.
· natural disasters ­ the more prone a region is to drought, famine, disease,
earthquake or tsunamis, the higher the DR.
· war ­ = deaths = immediate drop in pop. and a longer term fall as a result of
fewer fertile adults.
number of deaths per year
DR = --------------------------------------------- x 1000
tot. pop. in same year…read more

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Population structure.
· In MEDCs ( N. America, Europe), there has been a large
increase in life expectancy.
· Demographic transition (DT) : the transition from high
birth and death rates to low birth and death rates as a
country develops from a pre-industrial to an industrialized
economic system.
· It doesn't automatically follow that what happens in one
pop. will happen in another as they develop
economically. ­ not all countries are necessarily affected
by DT.
· it's useful to know the age and gender profile of a pop. to
calculate the future size of the human pop. which
depends on the number of females of child ­ bearing
· this is displayed graphically by age pop. pyramids.…read more

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