Name Class Date

5.3 Human Population Growth

Lesson Objectives
Discuss the trend of human population growth.
Explain why population growth rates differ in countries throughout the world.
Lesson Summary
Historical Overview The size of the human population has increased over time.
For most of human existence, limiting factors such as the scarcity of food kept death rates high.
As civilization advanced, agriculture, industry, improved nutrition, sanitation, and medicine reduced death rates. Birthrates stayed high in most places. This led to exponential growth.
Today, the human population continues to grow exponentially, although the doubling time has slowed.

Patterns of Human Population Growth Demography is the scientific study of human populations. Demographers try to predict how human populations will change over time.
Over the past century, population growth in developed countries slowed. As death rates dropped, birthrates dropped also. Demographers call this shift the demographic transition. Most people live in countries that have not undergone the demographic transition.
An age-structure graph shows how many people of each gender are in each age group in a population. Demographers use such graphs to predict how a population will change. More people of reproductive age usually means faster growth.
Many factors, including disease, will affect human population growth in the twenty-first century. Current data suggest the human population will grow more slowly over the next 50 years than it did for the last 50 years.

Historical Overview
For Questions 1–5, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.
INCREASED 1. Over the last 1000 years, the size of the human population has decreased.
EXPONENTIAL 2. Since the 1800s, human population growth has been