The Ghost of Populations Past
(Adapted from assignment generated by Callahan, Hoffman, & Tipps, 1991)
OBJECTIVES:
1.To accurately collect data regarding age of death of humans from tombstones, newspaper obituary listings, or
other resources. (See Teacher Notes)
2. To analyze data by developing line graphs, bar graphs, and age population pyramids of collected data. A
survivorship curve will be generated.
3. To gain an understanding of age structure of a population and possible effect upon future population size.
4. To develop an awareness of the effects of age on death rate.
BACKGROUND:
Population studies are an important aspect of the study of ecology. It is important to remember that a population
is a collection of individuals of the same species. Populations have their own distinct characteristics apart from
any one individual of the population. One of these characteristics is size - how many individuals are in the
population. The study of changes in population size involves two primary components: birth rate and death rate.
If these two rates remain equal, the population size will generally remain the same. What other factors may
affect population size? What will have to happen for a population to increase in age? Decrease?
In this activity the age-related death rate of the human population will be studied. Information about the deaths
of humans will be gathered in one of a variety of ways and organized into a life table. An analysis of this
information will enable us to understand ages at which the human population is most vulnerable to death. What
age groups would you predict to be most vulnerable to death? What factors might contribute to the increased
rate of death during those predicted age groups?
MATERIALS:
• Age-of-Death Resource (actual visit to cemetery or online obituaries through various newspaper sources)
• Spreadsheet program for organization and sorting of material
• graph paper
• calculator, optional
PROCEDURE:
1.In a spreadsheet program, collect the following data from the information source, with one individual: Date of
Birth, Date of Death, Age (you can calculate this later), and gender. If visiting a cemetery, use 3 x 5 inch index
cards for each person to bring to class. Each individual in a group of 4 MUST obtain 50 entries. This way group
has 200 sets of data at their disposal to work with.
2.Separate data by: A. Gender B. Age groups according to Data Table (can be done by selecting all data in
tables (Not HEADERS) and going to “Data” Menu and selecting “Sort” Choose Gender and set it as either Male
or Female first, then by “age” “Lowest to highest”).
3.Count individuals in each group and enter in the Data Table. (These numbers represent "D" in your Life Table.)
4. Generate a data table that identifies the number of deaths for each 10 year age group per gender (0-9, 10-19,
20-29, etc). Title: “Obituary Data Collected of 200 individuals”
ANALYSIS:
1. Completion of life tables. Generate a Life Data Table that has the following information within it:
Cemetery Life Table
Age Interval
(X)
# in Study
I
Male Female
# Who Die in Interval
D
Male
Female
0-9
10-19
*Data table should continue for all age ranges in 10 year intervals up to 100+
Mortality Rate
M
Male
Female
2.For both males and females, determine the number of individuals (D) for each age group from your data tables.
Enter the total # of individuals in the study at I for 0-9 years of age. Subtract D0-9 from I 0-9 to determine I
for 10-19 years, and so on. (For example, if there was a total of 250 individuals in your study and 7 of them
died between the ages of 0-9, 243 individuals would be left in the study for age 10-19.)
3.Construct a line graph of age group (x) vs. # of individuals left in study (I). This represents your survivorship
curve. Plot male and female survivorship curves on the same graph.
4. Plot a population age pyramid (histogram) for male and female of each age group. 5. Determine mortality rate (M) by dividing # deaths by # individuals in each age group: M = D/I.
Plot a histogram of mortality rate vs. age group.
6. Hand graph each of the above graphs to hand in when activity is due. Data tables can be computer generated
or hand-created.
DISCUSSION: Post your answers on student page of jtenvironmentalissues.wikispaces.com. Title –
“Ghost of Populations Past”
1. What is the dominant age group in terms of numbers in your population study? In terms of mortality: If this is
a 20th century population, how does the distribution affect your life?
2.From your graphs can you tell if the population is stable, expanding, or declining? Explain why this may be so.
3.What age periods have the highest death rate? Suggest factors that contribute to the higher death rate during
those periods.
4. Compare the survivorship curve of females and males. How do they differ?
5. How do life insurance companies use such data as we have collected?
6. Go to: http://www.algebralab.org/practice/practice.aspx?file=Reading_AgeStructure.xml and complete the
activities. Provide your answers to the questions that follow.
7.After working through the activity at the above website, compare the 3 different types of pyramids and
identify/describe the major differences between each of the three growth scenarios (rapid, slow, and decline).