Do populations continuously grow?
Not necessarily. The growth of a population depends on a number of issues. Obviously, the average age of the individuals of that population is important. But other factors, such as the local economy, also play a role.
Major changes in the human population first began during the 1700s in Europe and North America. First death rates fell, followed somewhat later by birth rates.
Death Rates Fall
Several advances in science and technology led to lower death rates in 18th century Europe and North America:
- New scientific knowledge of the causes of disease led to improved water supplies, sewers, and personal hygiene.
- Better farming techniques and machines increased the food supply.
- The Industrial Revolution of the 1800s led to new sources of energy, such as coal and electricity. This increased the efficiency of the new agricultural machines. It also led to train transport, which improved the distribution of food.
For all these reasons, death rates fell, especially in children. This allowed many more children to survive to adulthood, so birth rates increased. As the gap between birth and death rates widened, the human population grew faster.
Birth Rates Fall
It wasn’t long before birth rates started to fall as well in Europe and North America. People started having fewer children because large families were no longer beneficial for several reasons.
- As child death rates fell and machines did more work, farming families no longer needed to have as many children to work in the fields.
- Laws were passed that required children to go to school. Therefore, they could no longer work and contribute to their own support. They became a drain on the family’s income.
Eventually, birth rates fell to match death rates. As a result, population growth slowed to nearly zero.
Stages of the Demographic Transition
These changes in population that occurred in Europe and North America have been called the demographic transition. The transition can be summarized in the following four stages, which are illustrated in the figure below:
- Stage 1—High birth and death rates lead to slow population growth.
- Stage 2—The death rate falls but the birth rate remains high, leading to faster population growth.
- Stage 3—The birth rate starts to fall, so population growth starts to slow.
- Stage 4—The birth rate reaches the same low level as the death rate, so population growth slows to zero.
- Major changes in the human population first began during the 1700s. This occurred in Europe and North America.
- First, death rates fell while birth rates remained high. This led to rapid population growth.
- Later, birth rates also fell. As a result, population growth slowed.