1. Section 14-3: Human Population Growth
Chapter 14: Populations
Section 14-3:
Human Population Growth

2. Growth Increases
For most of human existence, human populations grew slowly because of population-limiting factors like harsh conditions, lack of food, predators, and parasites
Until recently, only half of children lived to adulthood and families had many children to ensure some of them would survive

3. Quick Growth Human population began exploding ~300 years ago
Agricultural/industrial revolutions have made human life easier, allowing people to combat population-limiting factors
More nutritious foods are more readily available, doctors can cure, treat, and prevent many diseases, better health care has led to more infants surviving

4. Quick Growth
All of these factors combined to lower human death rates, and birth rates have either stayed the same or increased
Currently, the human population is now in a state of exponential growth – about 180 people are born every minute, which is about 92 million more humans each year

5. Population Clocks

6. Controlling Human Populations
Human populations would stop growing if birth rates fell, death rates rose, or both
In some countries/parts of the world, population growth has slowed
These populations have gone through the demographic transition, which is a change in growth rate resulting from changes in birth rates

7. Demographic Transition
Stage 1: There is a high birth rate and a high death rate.
Families have many children to ensure some will survive.
Population growth is slow because birth rate and death rate are both high.

8. Demographic Transition
Stage 2: Improvements are made in living conditions.
Food production increases, advances are made in medicine and sanitation.
More children live to adulthood and death rate decreases while birth rate remains high, leading to rapid population growth.

9. Demographic Transition
Stage 3: Birth rate decreases.
More children survive, therefore families have fewer children.
Birth rate and death rate reach balance at a lower level.
Population growth slows down and may stabilize.

10. World Population Growth
World population continues to grow exponentially because most people live in countries that have not yet completed the demographic transition
The US, Canada, Japan, and most European countries have gone through all three stages
The countries of Asia, Africa, and South America have not yet gone through demographic transition

11. World Population Growth
Future population growth in various countries depends, in part, on how many people of different ages are living in that country today
Age Structure Diagrams – show the percentage of the population of individuals within a 5-year age group

12. Age-Structure Diagrams