1. Population Dynamics

2. Population Growth Populations grow exponentially
Exponential growth is an increase by a percentage
Looks like a curve when graphed
J-CURVE is a special type of exponential growth in which the percentage changes over time. When graphed, it looks like a “J”
Example: the human population, insect populations, etc.

3. Populations grow until they meet the limits of their resources.
Carrying capacity (K) is the number of individuals an area can support indefinitely.

4. The Human Population has a carrying capacity
Effects of a large human population:
Food and other resource shortages
Job shortages
Increased pollution and habitat disruption
Disease epidemics
Increased crime, war, etc.

5. Populations in nature fluctuate around their carrying capacity.

6. Populations cannot exceed the carrying capacity
If “K” is exceeded, the population could crash or cease to exist.
This graph is for a real population of deer in Arizona that was almost wiped out when predators were removed

7. HUMAN POPULATION GROWTH
For most of the history of humans on earth, the growth rate was about 0.002%.
During late 1800’s, the percentage changed.
In 1974 it reached its highest growth rate at 2.78%.
Today the world growth rate is less than 1.17%.
The graph forms a very steep “J”.

8. Why did the population grow so fast?
These changes are not due to a change in crude birth rate, but rather a change in the death rate and infant mortality due to:
BETTER HYGIENE
BETTER NUTRITION
INDUSTRIALIZATION
MECHANIZED FARMING
PESTICIDES TO PROTECT OUR FOOD SOURCES
MEDICINES, ANTIBIOTICS

9. Why has the population growth decreased since 1970 (from 2. 78 to 1
Decrease in population growth since the 1970’s is mainly due to available birth control and women becoming educated and entering the work force
The growth rate varies considerably from country to country
China 0.6%
US 1.10%
Kenya 2.79%

10. What is a demographer? Demographers study populations
Collect data on age of individuals, birth rates, fertility rates, death rates, etc.
Predict future population growth
A large proportion of young people indicates future growth
Which of these two countries will grow quickly in the next several years?

11. % change = (birth rate + immigration)-(death rate + emigration) X 100 1000 People

12. Demographers measure distribution of birth rate by age group

13. Fertility Rates
Replacement level fertility is the number of children a couple must have to replace themselves when they die. Varies due to differences in child mortality.
More developed countries (US, Canada, Australia, Western Europe, Japan) = 2.1 children per couple
Less developed countries = 2.5 (much higher in some)
Total fertility rate is the total number of children a woman will have if she survives her childbearing years (age 15-44). Varies due to cultural, religious values.

14. Global Fertility Rates
Fertility rates are used by demographers to predict
population growth around the world.

15. Factors Effecting Total Fertility
Varies in from one population to the next due to:
EXPENSE OF RAISING A CHILD
EDUCATION OF WOMEN, JOB AVAILABILITY
IMPORTANCE OF CHILDREN TO WORK
AVAILABILITY OF PRIVATE AND PUBLIC RETIREMENT
AVAILABILITY OF RELIABLE BIRTH CONTROL
CULTURAL REASONS (HAVING SONS, ETC)
AGE OF MOTHER AT HER FIRST CHILD’S BIRTH

16. Fertility varies among more developed countries

17. Fertility varies widely among less developed countries.
Where women are educated, fertility rates are lower.

18. Demographic Transition growth rates change as nations become industrialized.