1. Human Populations

2. Human Population and History
For most of time Human population grew slowly
Limiting factors kept population sizes low
Life was harsh
Food was scarce
Incurable diseases were rampant

3. About 500 years ago human population began growing more rapidly
Agriculture and Industry made life easier
Food supply more reliable
Shipment of goods became easier
Improved sanitation and medicine decreased death rates

4. Birthrates remained high as death rates decreased.
What would this mean for the population growth??

5. Demography Demography – scientific study of human populations
Estudio científico de poblaciones humanas

6. Age-Structure Diagrams

7. Review
Which one is exponential growth?
Which one is logistic growth?

8. Logistic Growth As resources become less available, the growth of a population slows or stops.
Draw a picture of a traditional Logistic graph

9. Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially.
Draw an example of a traditional exponential growth curve

10. Three factors can affect population size: the number of births,
the number of deaths,
and the number of individuals that enter or leave the population.

11. Immigration Emigration
the movement of individuals into an area, is another factor that can cause a population to increase
Emigration
the movement of individuals out of an area, can cause a population to decrease in size.

12. Carrying Capacity
Largest number of individuals of a population that a given environment can support.
What factors can control the carrying capacity? (list abiotic and biotic)

13. 3.Exponential growth in a population slows down or stops as
1.When the birthrate of a population exceeds its death rate, the population
A.decreases. C.stays the same.
B.increases.
2.An S-shaped curve on a graph of population growth is characteristic of
A.exponential growth. C.carrying capacity.
B.logistic growth.
3.Exponential growth in a population slows down or stops as
A.resources become limited.
B.rate of immigration increases.
C.rate of emigration decreases