1. THE HUMAN POPULATION
Think of the earth as a living organism that is being attacked by billions of bacteria whose numbers double every forty years. Either the …bacteria dies, or both die. - Gore Vidal

2. HUMAN DEMOGRAPHY Demographics – The study of human populations.
Births, deaths, gender, race, and economic status.
Population
Group of individuals of the
same species in a specific area
Characteristics of a population:
Range – geographic distribution
Density – number of individuals per unit area
Growth rate – increase in population over time
Immigration – movement of individuals into the area
Emigration – movement of individuals out of an area
Age structure – younger vs. older individuals

3. GROWTH RIDDLE
A wealthy, eccentric relative of yours passes away. You are listed as the primary beneficiary on the will. You have two options for collecting the money.
Option 1:$200,000 per day for thirty days.
Option 2: One penny doubled every day for thirty days

4. SOLUTION Option 1: Option 2: 30days x $200,000 = $6,000,000
Over $18,000,000!

5. EXPONENTIAL GROWTH (J-shaped)
A Density-Dependent Limiting Factor
EXPONENTIAL GROWTH (J-shaped)
Section 5-2
Growth of Aphids
Exponential growth
Peak population
size
Rapid decline
Steady population
size
Steady population
size
UNDER IDEAL CONDITIONS WITH UNLIMITED RESOURCES A POPULATION WILL GROW EXPONENTIALLY.
Go to Section:

6. LOGISTIC CURVE (s-shaped)
Figure 5-4 Logistic Growth of Yeast Population
LOGISTIC CURVE (s-shaped)
Section 5-1
Carrying capacity
Carrying Capacity- The largest number of individuals that an environment can support. Limited by the resources available.
Number of Yeast Cells
Time (hours)
AS RESOURCES BECOME LESS AVAILABLE THE GROWTH OF A POPULATION SLOWS OR STOPS.
Go to Section:

7. 2 TYPES OF LIMITING FACTORS
Limiting factors cause population growth to decrease
Density-dependent
Depends on the population size
Competition
Predation
Parasitism
Disease
Density-independent
Extreme weather, human activity, seasonal cycles

8. EXCEEDING THE CARRYING CAPACITY
Reindeer introduced to a small island off of Alaska in the early 1900s exceeded the carrying capacity, with an "overshoot" followed by a "population crash" in which the population was totally decimated by the mid–1900s.
Fig. 10–5
© Brooks/Cole Publishing Company / ITP

9. POPULATION CURVES IN NATURE
Population cycles for the snowshoe hare and Canadian lynx are believed to result because the hares periodically deplete their food, leading to first a crash of the hare population and then a crash of the lynx population.
Fig. 10–8
© Brooks/Cole Publishing Company / ITP

10. POPULATION GROWTH
For most of human history, humans have not been very numerous compared to other species.
It took nearly 72,000 years to reach 1 billion.
150 years to reach 3 billion.
25 years to reach 4 billion.
20 years to reach 5 billion
12 years to reach 6 billion.
Human population tripled during the twentieth century…
World Population “Dots” Video

11. HUMAN POPULATION HISTORY

12. HUMAN POPULATION GROWTH
Exponential Growth
Human population has increased
Rates of growth have also increased
Currently about 2% per year
Doubling Time:
Estimation of how long for a population to double in size
When growth is exponential:
Doubling Time = 70 / annual % growth
70/2.0% = 35 years

13. TWO DEMOGRAPHIC WORLDS
Developing countries are poor, young, and rapidly growing.
India, China, Bolivia (S. America), Congo (Africa)
Contain 80% of world population, and will account for 90% of projected growth.
Developed countries are wealthy, old, and mostly shrinking.
United States, Japan, France
Populations often expected to decline.

14. ESTIMATED HUMAN POPULATION GROWTH

15. MEASUREMENTS OF POPULATION GROWTH
Fertility Rate - Number of births per 1000 women per year.
Developing countries = ~20
Developed countries = ~10
Total Fertility Rate – Average number of children a woman has in her lifetime.
Congo = 4.41
India = 2.68
U.S. = 2.1
The replacement level is when you have 2.1 children per couple.

16. FERTILITY RATE OF UNITED STATES

17. LIFE EXPECTANCY

18. MIGRATION The movement of individuals between areas.
Emigration: Move out of an area
Immigration: Move into an area

19. Population Essay Compare and Contrast
What shape population growth curve would you expect to see in a small town made up of mainly senior citizens?
Compare this growth curve to that of a small town made up of newly married couples in their twenties.

20. Survivorship & Age Structure

21. SURVIVORSHIP
Life Expectancy - Average age a newborn can expect to attain in any given society.
Most affected by infant mortality rates.
Strongly correlated with income up to about $4, (U.S.) per person.
What happens if the number of retirees exceeds the number of working adults?

22. R-strategists vs. K-strategists
R = “Reproducers”
K = “Care-givers”
Produce many small and unprotected young
Live in places where resources are temporarily abundant.
Opportunistic species
Ie. cockroaches, dandelions
Produce few large and well cared for young
Live in places where resources are limited.
Good competitors.
Ie. elephants, saguaro cactus
Fig. 10–7a
© Brooks/Cole Publishing Company / ITP

23. Survivorship curves Three kinds of curves:
late loss (usually K–strategists), in which high mortality is late in life;
constant loss (such as songbirds), in which mortality is about the same for any age;
early loss (usually r–strategists), in which high mortality is early in life.
Fig. 10–9
© Brooks/Cole Publishing Company / ITP

24. UNITED STATES BIRTH RATE

25. DEMOGRAPHIC TRANSITION
Model of how economic development alters population dynamics.
Preindustrial
Food shortages, malnutrition, lack of sanitation and medicine keep death rates high.
Birth rates tend to match death rates to maintain the population.
Early Transitional
Hygiene, nutrition, and education improve.
Death rates drop dramatically.
Birth rates remain high initially.
Population increases very quickly.
3. Late Transitional
Birth rates begin to fall.
Population may have increased from 2x to 4x by this point.
4. Industrial
Transition is complete.
Both death and birth rates are low.
Population is in equilibrium.

26. DEMOGRAPHIC TRANSITION

27. AGE STRUCTURE DIAGRAMS
Age Structure: Distribution of ages in a population at a specific time.
Graphed as a population pyramid.
More young people in a population usually means higher growth rates.

28. FUTURE OF HUMAN POPULATIONS
Most demographers believe the world population will stabilize sometime during the next century.
Projections of maximum population size:
Low 8 billion
Medium 9.3 billion
High billion

29. Age Structure Pyramid Comparison
Compare and contrast the countries in terms of their pyramids. What do the pyramids tell us? (address the following- rate of population growth, living standard characteristics, trend towards stability/instability, access to education and jobs, and access of technology).