8.1 HUMAN POPULATION DYNAMICS
Significant ideas
● A variety of models and indicators are employed to quantify human population dynamics.
● Human population growth rates are impacted by a complex range of changing factors.
Applications and skills
● Calculate values of CBR, CDR, TFR, DT and NIR.
● Explain the relative values of CBR, CDR, TFR, DT and NIR.
● Analyse age/sex pyramids and diagrams showing demographic transition models.
● Discuss the use of models in predicting the growth of human populations.
● Explain the nature and implications of exponential growth in human populations.
● Analyse the impact that national and international development policies can have on human
population dynamics and growth.
● Discuss the cultural, historical, religious, social, political and economic factors that influence human
population dynamics.
Understandings
1. Demographic tools for quantifying human population include crude birth rate (CBR), crude death
rate (CDR), totality fertility rate (TFR), doubling time (DT) and natural increase rate (NIR).
2. Global human population has followed a rapid growth curve but there is uncertainty as to how this
may be changing.
3. As the human population grows, increased stress is placed on all of Earth’s systems.
4. Age/sex pyramid and demographic transition models (DTM) can be useful in the prediction of
human population growth. The DTM is a model which shows how a population transitions from a
pre-industrial stage with high CBR and CDR to an economically advanced stage with low or
declining CBR and low CDR.
5. Influences on human population dynamics include cultural, historical, religious, social, political
and economic factors.
6. National and international development policies may also have an impact on human population
dynamics.
Human population statistics
Demographics is the study of the dynamics of population change.
,Global population growth rate follows an exponential curve, an accelerating rate of growth which is
proportional to the population size e.g. 2 to 4, 4 to 8, 8 to 16.
● high variant – CDR will continue to fall rapidly but the CBR will continue to fall slowly.
● medium variant – the middle ground and a straightforward projection of the curve.
● low variant – we will not find a cure to major diseases and the CBR will fall.
Statistics or any graph of projected human population growth estimates vary because:
● they are based on past and current trends.
● mathematical formulas assume human behaviour is predictable, e.g. no war and disease.
● it is difficult to build in the impact of the demographic structure of the population.
, Measuring population changes
Four main factors that affect population size of organisms:
● birth rate
● death rate
● immigration
● emigration
Fertility rate is the number of births per thousand women of childbearing age.
● replacement fertility is 2.03 in MEDCs and 2.16 in LEDCs because of infant and childhood mortality.
Crude birth rate (CBR) is the number of births per thousand individuals in a population per year.
● = (births/population) × 1000.
Crude death rate (CDR) is the number of deaths per thousand individuals in a population per year.
● = (deaths/population) × 1000.
Natural increase rate (NIR) is the rate of human growth expressed as a percentage change per year.
● = (crude birth rate – crude death rate) / 10 [migration is ignored].
Doubling time (DT) is the time in years that it takes for a population to double in size.
● = 70 / NIR because an NIR of 1% will make a population double in size in 70 years.
Total fertility rate (TFR) is the average number of children each woman has over her lifetime.
LEDCs and MEDCs
The Human Development Index (HDI) by the UNDP is a measure of a country's ‘well-being’ and combines:
● health (life expectancy)
● wealth (GDP per capita)
● education
Significant ideas
● A variety of models and indicators are employed to quantify human population dynamics.
● Human population growth rates are impacted by a complex range of changing factors.
Applications and skills
● Calculate values of CBR, CDR, TFR, DT and NIR.
● Explain the relative values of CBR, CDR, TFR, DT and NIR.
● Analyse age/sex pyramids and diagrams showing demographic transition models.
● Discuss the use of models in predicting the growth of human populations.
● Explain the nature and implications of exponential growth in human populations.
● Analyse the impact that national and international development policies can have on human
population dynamics and growth.
● Discuss the cultural, historical, religious, social, political and economic factors that influence human
population dynamics.
Understandings
1. Demographic tools for quantifying human population include crude birth rate (CBR), crude death
rate (CDR), totality fertility rate (TFR), doubling time (DT) and natural increase rate (NIR).
2. Global human population has followed a rapid growth curve but there is uncertainty as to how this
may be changing.
3. As the human population grows, increased stress is placed on all of Earth’s systems.
4. Age/sex pyramid and demographic transition models (DTM) can be useful in the prediction of
human population growth. The DTM is a model which shows how a population transitions from a
pre-industrial stage with high CBR and CDR to an economically advanced stage with low or
declining CBR and low CDR.
5. Influences on human population dynamics include cultural, historical, religious, social, political
and economic factors.
6. National and international development policies may also have an impact on human population
dynamics.
Human population statistics
Demographics is the study of the dynamics of population change.
,Global population growth rate follows an exponential curve, an accelerating rate of growth which is
proportional to the population size e.g. 2 to 4, 4 to 8, 8 to 16.
● high variant – CDR will continue to fall rapidly but the CBR will continue to fall slowly.
● medium variant – the middle ground and a straightforward projection of the curve.
● low variant – we will not find a cure to major diseases and the CBR will fall.
Statistics or any graph of projected human population growth estimates vary because:
● they are based on past and current trends.
● mathematical formulas assume human behaviour is predictable, e.g. no war and disease.
● it is difficult to build in the impact of the demographic structure of the population.
, Measuring population changes
Four main factors that affect population size of organisms:
● birth rate
● death rate
● immigration
● emigration
Fertility rate is the number of births per thousand women of childbearing age.
● replacement fertility is 2.03 in MEDCs and 2.16 in LEDCs because of infant and childhood mortality.
Crude birth rate (CBR) is the number of births per thousand individuals in a population per year.
● = (births/population) × 1000.
Crude death rate (CDR) is the number of deaths per thousand individuals in a population per year.
● = (deaths/population) × 1000.
Natural increase rate (NIR) is the rate of human growth expressed as a percentage change per year.
● = (crude birth rate – crude death rate) / 10 [migration is ignored].
Doubling time (DT) is the time in years that it takes for a population to double in size.
● = 70 / NIR because an NIR of 1% will make a population double in size in 70 years.
Total fertility rate (TFR) is the average number of children each woman has over her lifetime.
LEDCs and MEDCs
The Human Development Index (HDI) by the UNDP is a measure of a country's ‘well-being’ and combines:
● health (life expectancy)
● wealth (GDP per capita)
● education
