Check out my
carrying
capacity!

Read the board!
Soooo . . . Good thing we’re
human and those population
ecology rules don’t apply to
us . . . Right?
Or do they?




What part(s) of the
sigmoidal curve do
you see?
Name two densitydependent and
two densityindependent
factors that apply
to humans.
Are we r- or Kstrategists? Defend
your answer.
How do humans
avoid the LotkaVolterra model?
Human population milestones
THE ULTIMATE IN CARPOOLING? LOL
Check this out!
Which parts of the S-curve of population
growth are already apparent?
Hunter Gatherer societies

Nomadic – moved
around

Small family groups

Life expectancy low –
poor nutrition, no
disease prevention,
hard life

Population was small
because of limiting
factors
What was the Agricultural
Revolution, and how long ago did
it happen?
Agricultural revolution – 8,000 BCE
People learned how to grow food – a new
technology that changed limitations of food
Change #1. Food surplus created
demand for larger families (more
kids meant more food produced)
Children increase agricultural
productivity
Change #2. Settlements created
along waterways for transportation
– now people could trade for
goods and food, even if they had a
bad farming year.
What was the only time that
population decreased
significantly?
Bubonic Plague – 1390’s In Europe, killed 1/3
of population
Thomas Malthus

Early 1800’s

Food is necessary for survival

“Passion between the sexes is
necessary and will remain
nearly in its present state”

Population growth will
exceed Earth’s ability to
supply food

“premature death must in
some shape visit the human
race . . . Epidemics,
pestilence and plague
advance in terrific array, and
sweep off their thousands
and ten thousands”
When did humans begin their
exponential growth?
Changes after 1930

Better nutrition (more variety, better preservation,
greater quantity increased life expectancy)

Better sanitation (running water, sewage systems,
garbage collection reduced death and disease)

Better health care (germ theory of disease,
antibiotics reduced death and disease)
How big will our population
get?

UN projection: 9.3 billion by
2050

World growth rate is has
been decreasing since
1967

China’s peak projected for
2026 at 1.4 billion and then
by 2045 it will be smaller
than today
Check for understanding.

What are the three parts of the S-curve of
population growth?

Does a population know when it reaches carrying
capacity?

What happens to a population that goes above its
carrying capacity?

Name four limiting factors that would set the
carrying capacity for humans.

Why would the three changes after 1930 increase
population size?
OK, but not every country is
growing at the same rate!

What causes some countries to grow faster than
others?

Tonight – visit www.prb.org to gather data for one
country.
Write down your country on the
sheet so you don’t forget!

United States

Thailand

China

Afghanistan

Russia

Saudi Arabia

Mexico

Pakistan

Nigeria

Colombia

India

Venezuela

Sweden

El Salvador

Brazil

Spain

Germany

Italy
Video time! Visualize – why are
some countries growing faster?
 While
you watch – write
notes: What are all the
reasons Indian women
are having more children
than American women?