1.) Population structure

Sex ratio
- The number of males per 100 females in world population

- Women tend to live 7 years longer than men

Demographic transition
- Why natural increase rises and falls?
- No country has ever reverted to a previous stage in either the beginning, middle, or end

stage 1 - low growth
stage 2 - high growth
stage 3 - moderate growth
stage 4 - low growth

Declining birth rates
- 2 strategies for lowering birth rates

1.) improve education and health care

2.) contraception