In the past, there were 20 times more children than older people. Then there were 7 times more people under age 15 than over age 64. Currently, there are 3 times as many children as there are elders. These changes in the age make-up of the population are referred to as .

The correct answer is:  Demographic shift

Explanation:

It is a phenomenon that refers to the historical shift or change from high birth rates and high infant death rates to low birth rates and low death rates in more advanced societies. This information has a direct connection to the growth rate of the population. What is mainly does is to describe population change over time.

demographic shift.

Explanation:

The main thing we should note from the question is that there is high birth rate and the evidence to this can be found in the first statement which says; ''... there were 20 times more children than older people''.

The term used in the demography for describing the rate of the transition at which infants are been giving birth to is known as the demographic shift or demographic transition.