Discussion:
How does population increase?
How does it decrease?
How can age of marriage affect population size?
How can we measure populations?
Why is China's still growing after 30 years of "one child policy?
Why do people migrate?
Are push factors or pull factors more important when deciding to migrate?
Can you explain the trend in the graph below?
Doubling time: Rate of increase relating to time it takes population to double
70/Rate of National Increase in %, RNI (must be positive)
1% RNI = 70 year doubling time
2% RNI = 35 year doubling time
Rates of increase have risen during human history = doubling times shortened.
Question: If fertility rates decline (as they have been), what will happen to doubling times?
Demands for different goods
Needs for education or healthcare
Possible employment numbers
Foretell future problems
Imbalance of sexes ( eg: China has too many boys)
Dependency ratio : Number of dependents / people in productive years (age 16 to 64)
Large number’s of young or old = high dependency ratio
See textbook p. 402: Triangular Graph
Ageing dependency ratio: Number of 65+/people in productive years (age 16 to 64)
Youthful dependency ratio: Number of 0-15/people in productive years (age 16 to 64)