diving deeper notes 3

• population structure
• sex ratio
• defined as the number of males per 100 females in the populatio
• demographic transtion
• why natural increase rises and falls
• four stages
• stage 1: low growth
• marked byvery high birth and death rates
• stage 2: high growth
• marked by rapidly declining death rates and very high birth rtes
• stage 3: moderate growth
• marked by rapid decline in birth rate and steady decline in death rate
• stage 4: low growth
• marked by very low birth and death rates
• population change in result from immigration
• declining birth rates
• two successful strategies for lowering birth rates
• improving education and health care
• contraception (birth control)