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.