# Laboratory 6 Population Demographics The simulator for population demographics for this lab

Laboratory 6 Population Demographics

The simulator for population demographics for this lab is located at this website: https://www.learner.org/wp-content/interactive/envsci/demographics/demog.html

For your lab, you will work through the simulator online, completing 3 population activities. Complete the 3 pages of tables and type the answers to the questions after each activity. Save and submit ONLY the tables and questions for the 3 activities (do not include the background or steps). You can type directly into the tables or print them and write in the answers and then scan them. You must type up the Discussion Question answers.

Activity 1: The Demographic Transition

Background

At the most basic level, the increase or decrease in population can be calculated by following the simple formula:

BIRTH RATE – DEATH RATE + IMMIGRATION = GROWTH RATE

Note that this simulation does not take immigration into account, so we are looking at birth and death rates only. Birth and death rates are expressed in a number of different ways. For use in predicting population growth, population models use birth and death rates specific to each age group, over a step of 5 years. The age-based population structure is also greatly affected by the current stage of demographic transition. The Population by Age Group graph is a standard representation of population structure, called a population pyramid.

In this simulator, the overall rates are shown on buttons in the grey “Vital Rates” box. When you click the buttons with the pencil icon in this box, a detail dialog shows the age group specific rates.

Be sure Demographic Transition is selected in the top “Lesson” dropdown menu. Look first at the United States pyramid for 2015. Fill out the following data in Table 1.

Write down the 2015 growth rate and what you predict the shape of each pyramid might be in 2050 as you look at the initial pyramid for each country, and why, on the first data table.

For example, the United States has a house-shaped pyramid. Will it stay that way or change?

Other countries look like a severe pyramid, an onion dome or an inverted pyramid (decreasing population).

Start by running the simulator to 2050 for the United States. Click on Run button.

Record the population growth rate and pyramid shape at the end of the simulated period in the Data Table #1.

Do the same for the other 8 countries, selecting them one by one in the Country dropdown menu.

Now number the countries by population growth rate from highest as #10 (earliest in the demographic transition) to lowest as #1 (farthest along the transition) as of 2015. Use the last column in the table labeled, “Rank Transition Order.”

Compare the pyramid shape of the countries that you found to be farther along in the transition to those that are earlier in the transition. Do any patterns emerge?

Then type your responses to the following questions to submit. Title it as Activity 1 Discussion Questions

Think of three positive social factors that contribute to lower birth rates in the countries farther along in development. List and briefly describe the three factors. How might these social conditions be encouraged to emerge in less developed countries?

People in the “prime of life” (aged roughly 20-60, depending on local conditions), support the populations younger (their kids) and older (their elderly relatives) than themselves. How might this impact the quality of life in countries with various shapes of demographic pyramids now and in the future? Compare at least 3 countries in your discussion.

Activity 2: Population Momentum

Background

Now let’s explore population momentum, which is the time lag between a change in birth/death rates and the slowing of population growth. We will now consider how population changes are affected by the average age of motherhood.

Select Population Momentum in the “Lessons” dropdown menu.

Start by looking at the effect of changing the age of reproduction. Select Nigeria from the Country dropdown menu and run the simulator with the default settings to 2050.

Record the results in your Data Table.

Predict what will happen when the average age of childbearing women is increased by 5 years (fewer teenage pregnancies) and record your prediction (increase, decrease, stay the same) on the Data Table.

Now click on the Birth box. Click on the arrow to add 5 years to the average age of chold-bearing women. Hit Apply. Then back on the main page, hit reset.

Run the simulator and record the results.

Now increase the childbearing age by 15 years, run it, and then decrease it by 5 years, and record your results.

Use the Reset button at the bottom of the dialog to restore the original rates between each different treatment.

What if Nigeria suddenly had the same birth and death rates as the USA? In the simulator, click on the birth rates button, choose “USA” from the dropdown menu, and click “Apply.” Do the same for death rates.

Run the simulator to year 2150 by hitting the Run button three times. While doing so, watch the shape of the population pyramid (the graph by age group).

Now look at Japan, a country with a population structure almost the exact opposite to that of Nigeria. Write down your prediction about how this difference in population structure might affect the growth of the population.

Apply the same process you used to examine Nigeria to Japan. Select Japan from the Country pull down menu, run the simulator with the default settings to 2050, and record the results in your Data Table. Draw the results for Japan.

Predict what will happen when the average age of childbearing women is increased by 5 years (fewer teenage pregnancies) and record your prediction.

Run the simulator, and record your results.

Now increase the childbearing age by 15 years, and then decrease it by 5 years, and record your results.

Use the Reset button at the bottom of the dialog to restore the original rates between each different treatment.

Return to the simulator and change the birth and death rates to those of the USA. Again, run the simulator to year 2150, observing what happens to Japan’s population pyramid. Sketch the result and briefly explain the changes if any in the table.

Then type your responses to the following questions to submit. Title it as Activity 2 Discussion Questions

Discuss the shape of Nigeria’s and Japan’s pyramids and how they changed with American birth and death rates. What do the changes tell you? Did the patterns of population changes match your predictions? If not, why not?

Many European countries are giving monetary incentives to citizens who have multiple children. Why would they do this? How would a baby boom change Japan’s future, its demographics and the shape?

How does an increase or decrease in the average childbearing age change the population? Why?

Why do the most developed countries tend to have older childbearing women than still developing countries?

Activity 3: Social Impacts

Background

You just observed how two countries with the same birth and death rates by age group will eventually come to have populations with similar structures, with similar population pyramid shapes. It may take a while to get there. This is because the initial age structure of a population is key to its population growth.

Countries with large numbers of young people, like Nigeria, will go through a growth spurt as those young people age and have children. Conversely, the population of a country with a large elderly population past childbearing age, such as Japan, will dwindle as those older people die. Eventually these factors even out and a country with a near-replacement fertility rate will have a stable population like the USA. In the short term, however, a population structure has a momentum of its own.

Now consider the case study of China and its drastic approach to slow down population growth. In the 1970s the fertility rate was over 3.8 and the population was growing too fast. You will compare what happened between 1975 and the peak (and beyond) in two scenarios.

Select Social Impacts in the “Lessons” dropdown menu and China as the “Country.”

Even with extreme measures such as China’s “one-child” laws, a population growth rate cannot be changed quickly. China’s population control policies began in earnest around 1975. Look at the historical growth graph on the left for China. Real data is up until 2015 (it’s not 1 because rural families could have 2 kids). The projected line is based on the prediction from removing the one-child policy.

Keep the current (as of 2015) 1.52 birth rate. Click Run to see what would happen from 2015-2050 then to 2100 if China kept the one-child policy.

You can hit Reset to quickly see the original pyramid along with the current one.

In 2016, China relented (somewhat) on their one-child policy. Now increase the birth rate to 1.95, write it in your table, then run the simulation to 2050 (should follow the grey line) then 2100.

Record your results in the table.

Then type your responses to the following questions to submit. Title it as Activity 3 Discussion Questions.

For questions a, b, and c, look at the red projected line for the 1.52 rate. When will China’s population peak and at what number?

How long was the delay between starting the one-child policy in 1975 and when China’s population peaked? How many people were added during that delay?

What happen after the peak? Describe the trend.

Now compare the grey line numbers of 1.95 to the red projected line with a 1.52 birth rate. How different are the results (peak, number added, ending population) Did China need this rigid birth policy? Why or why not? Use your results comparing the red and grey line to justify your answer.

Do you think a country’s government should try to control population growth, either to decrease or increase births, such as in China or here in the United States?

DEMOGRAPHICS DATA TABLES (submit all with lab report)

ACTIVITY 1

Country

Predict Pyramid Shape 2050

Actual Pyramid Shape 2050

Birth Rate

2015/2050

Death Rate 2015/2050

Population Growth % 2015

Population Growth % 2050

Rank Transition Order

USA

Brazil

China

India

Indonesia

Iraq

Italy

Japan

Nigeria

DEMOGRAPHICS DATA TABLES: ACTIVITY 2

Activity 2: Population Pyramids

Nigeria

Original

2050

Prediction

Age +5 years

Simulated

+ 5 years

Simulated

Age +15 years

Simulated

Age -5 years

Birth rate

Death rate

Population Growth

Total

Population

Nigeria with USA Rates

Sketch results at 2150 and compare :

Activity 2: Population Pyramids

Japan

Original

2050

Prediction

Age +5 years

Simulated

Age + 5 years

Simulated

Age +15 years

Simulated

Age -5 years

Birth rate

Death rate

Population Growth

Total

Population

Japan with USA Rates

Sketch results at 2150 and compare:

DEMOGRAPHICS DATA TABLE

ACTIVITY 3

Activity 3: China

China

1975

Current

Without One Child

Birth rate

3.83

1.52

1.95

Death rate

—————-

Population Growth

—————-

Total Population

2050

—————-

Total Population

2100

—————-