Chapter 9

The Human

Population

...we were doing so good for so long....

what happened?

Revolution(s)!(industrial & scientific...)

• AGRICULTURE– Increases in food production– Better food distribution & storage

• PUBLIC HEALTH– Improved sanitation– Clean drinking water– Mass inoculations against disease

Earth cannot sustain this human population explosion for much

longer.

How BIG will human pop get before...?

• Demographers use:–Age structure diagrams –Survivorship studies–Fertility rate analysis–Migration

• ....predictions are often wrong...human behavior (not to mention nature!) can be capricious!

Age structure (population profile)

Age structure (population profile)

Which countries will have a problem caring for their elderly population?Why is Saudi Arabia’s graph so different from Italy’s?

Population profiles

• Allow governments/businesses to plan for future demand for goods & services

• Elementary schools or nursing homes?

• ...baby boomers say nursing homes...

• Have you heard about the pending Social Security “disaster?”

Survivorship• “% of group members

likely to survive to a given age”

• Type I: most people live to be very old (wealthy countries)

• Type II: similar death rate at all ages

• Type III: many children die (poor countries)

Fertility rate: “# of babies born each year per 1000 women in a given

pop”

Total fertility rate: “average # of children a woman gives birth to in

her lifetime”

Why did the US pop continue to grow in the ’90s even though the TFR was below the replacement

level?

Life Expectancy

• The dramatic increase in Earth’s pop in the last 200 years has happened because death rates have declined more rapidly than birth rates.

Life Expectancy

Declining Death Rates- Adequate food

- Clean water

- Sanitation

- Medical advances

Declining Infant Mortality - Parents’ access to:

Education

Food

Fuel

Clean water

THREATS to Life expectancy: AIDS...Tuberculosis...and other density-dependent factors.